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    Opioid Agonists

    BOXED WARNING

    Accidental exposure, alcoholism, ethanol ingestion, parenteral administration, potential for overdose or poisoning, requires an experienced clinician

    Like all opioid agonists, morphine; naltrexone is associated with a significant potential for overdose or poisoning; proper patient selection and counseling is recommended. Therapy requires an experienced clinician who is knowledgeable in the use of long-acting opioids for the management of chronic pain. Swallow capsules whole, or alternatively, the capsule contents may be sprinkled on applesauce. Do not crush, chew, or dissolve the capsules or the pellets within the capsules; tampering with this formulation in any manner, including crushing or dissolving, then snorting or administering via parenteral administration, may result in the release of a life-threatening dose of morphine and/or the release of a opioid withdrawal-precipitating dose of naltrexone in opioid-tolerant individuals. Morphine; naltrexone should be kept out of the reach of pediatric patients, as accidental exposure may cause a fatal overdose. Consumption with ethanol will result in additive CNS depressant effects and may lead to increased drug exposure that may cause a fatal overdose. Advise patients to avoid ethanol ingestion, including the ingestion of alcohol contained in prescription or non-prescription medications, during therapy. Patients with alcoholism should be advised of this serious risk, or an alternative medication should be used.

    Depression, substance abuse

    Morphine is an opioid agonist and therefore has abuse potential and risk of fatal overdose from respiratory failure. Addiction may occur in patients who obtain morphine; naltrexone illicitly or in those appropriately prescribed the drug. The risk of addiction in any individual is unknown. However, patients with mental illness (e.g., major depression) or a family history of substance abuse (including alcoholism) have an increased risk of opioid abuse. Assess patients for risks of addiction, abuse, or misuse before drug initiation, and monitor patients who receive opioids routinely for development of these behaviors or conditions. A potential risk of abuse should not preclude appropriate pain management in any patient, but requires more intensive counseling and monitoring. Abuse and addiction are separate and distinct from physical dependence and tolerance; patients with addiction may not exhibit tolerance and symptoms of physical dependence. The misuse of tablets by crushing, chewing, snorting, or injecting the dissolved product will result in uncontrolled morphine delivery and can result in overdose and death; naltrexone release may also precipitate withdrawal in physically dependent patients. To discourage abuse, the smallest appropriate quantity of morphine; naltrexone should be dispensed, and proper disposal instructions for unused drug should be given to patients.

    Asthma, bronchitis, chronic obstructive pulmonary disease (COPD), coadministration with other CNS depressants, cor pulmonale, emphysema, hypoxemia, obesity, pulmonary disease, respiratory depression, respiratory insufficiency, scoliosis, sleep apnea, status asthmaticus

    Use appropriate caution when considering opioid therapy in patients with respiratory impairment. Additionally, avoid coadministration with other CNS depressants unless no other alternatives are available, as this significantly increases the risk for respiratory depression, low blood pressure, and death. Morphine; naltrexone is contraindicated for use in patients with significant respiratory depression and/or acute or severe bronchial asthma (e.g., status asthmaticus) in unmonitored settings or in the absence of resuscitative equipment. Receipt of moderate morphine doses in these patients may significantly decrease pulmonary ventilation. Respiratory depression, if left untreated, may cause respiratory arrest and death. Symptoms of respiratory depression include a reduced urge to breathe, a decreased respiratory rate, or deep breaths separated by long pauses (a "sighing" breathing pattern). Carbon dioxide retention from respiratory depression may also worsen opioid sedating effects. Only healthcare professionals who are knowledgeable of the use of opioids for the management of chronic pain should prescribe morphine; naltrexone. The extended-release capsules should be reserved for patients in whom alternative treatment options (e.g., non-opioid analgesics or immediate-release opioids) are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain. Do not use extended-release capsules as a "prn" or "as needed" analgesic, for acute pain, or if the pain is mild or not expected to persist for an extended period of time. Proper dosing and titration are essential; patients should be monitored for respiratory depression, particularly during the first 24—72 hours after therapy initiation or after a dose increase. Caution should be exercised when converting from a different opioid to morphine; naltrexone, as initial dose overestimation may lead to fatal overdose. In patients with pulmonary disease such as chronic obstructive pulmonary disease (COPD), cor pulmonale, decreased respiratory reserve, hypoxia or hypoxemia, hypercapnia, emphysema, chronic bronchitis, respiratory insufficiency, upper airway obstruction, or preexisting respiratory depression, it is recommended that non-opioid analgesics be considered as alternatives to morphine; naltrexone, as even usual therapeutic doses may decrease respiratory drive and cause apnea in these patient populations. Extreme caution should also be used in patients with chronic asthma, kyphoscoliosis (a type of scoliosis), or paralysis of the phrenic nerve. Patients with advanced age, debilitation, or sleep apnea are at an increased risk for the development of respiratory depression associated with morphine. Use with caution in patients with obesity as this is a risk factor for obstructive sleep-apnea syndrome and/or decreased respiratory reserve. If treatment of respiratory depression in an individual physically dependent on opioids is necessary, administer the opioid antagonist with extreme care; titrate the antagonist dose by using smaller than usual doses. A high level of vigilant monitoring is recommended and supportive care should be given as needed.

    Labor, neonatal opioid withdrawal syndrome, neonates, obstetric delivery, pregnancy

    Morphine; naltrexone is classified as FDA pregnancy category C. There have been no adequate and well-controlled studies of morphine; naltrexone in pregnant women; however, retrospective and animal data for morphine are available. Morphine readily crosses the placenta. In animal studies, maternally toxic parenteral doses of morphine administered in the second trimester resulted in teratogenic damage in neurological, soft tissue, and skeletal systems. Third trimester exposure in rats and hamsters is associated with reversibly decreased brain, spinal cord, genital, and total body weights in offspring, as well as, delayed growth and maturation, and decreased fertility in both male and female offspring. Morphine; naltrexone is an extended release formulation of morphine not intended for short-term or as-needed dosing and is not indicated for use during labor or obstetric delivery. Further, prolonged maternal use of long-acting opioids, such as morphine; naltrexone, during pregnancy may result in neonatal opioid withdrawal syndrome (NOWS). This syndrome can be life-threatening. Severe symptoms may require pharmacologic therapy managed by clinicians familiar with neonatal opioid withdrawal. Monitor the neonate for withdrawal symptoms including irritability, hyperactivity, abnormal sleep pattern, high-pitched crying, tremor, vomiting, diarrhea, and failure to gain weight. Onset, duration, and severity of opioid withdrawal may vary based on the specific opioid used, duration of use, timing and amount of last maternal use, and rate of elimination by the newborn. Neonates whose mothers have been taking morphine chronically are frequently born small for gestational age, have decreased respiratory drive, and are at an increased risk of sudden infant death syndrome (SIDS). These newborns may show some respiratory depression and/or withdrawal symptoms at birth or within a few days. The risk of respiratory and CNS depression is especially important for premature infants, who are particularly sensitive.

    DEA CLASS

    Rx, schedule II

    DESCRIPTION

    Abuse-deterrent extended-release formulation of morphine with sequestered naltrexone for chronic severe pain
    Naltrexone has no therapeutic effect when product taken whole; if product crushed, chewed, or dissolved, uncontrolled drug delivery may result in withdrawal in the opioid-tolerant or lead to morphine overdose
    Avoid alcoholic beverages or medications that contain alcohol; co-ingestion may result in elevated morphine plasma concentrations that may be fatal

    COMMON BRAND NAMES

    Embeda

    HOW SUPPLIED

    Embeda Oral Cap ER: 100-4mg, 20-0.8mg, 30-1.2mg, 50-2mg, 60-2.4mg, 80-3.2mg

    DOSAGE & INDICATIONS

    For the treatment of chronic severe pain in patients who require daily, around-the-clock, long-term opioid treatment.
    NOTE: Extended-release morphine; naltrexone should be reserved for patients in whom alternative treatment options (e.g., nonopioid analgesics or immediate-release opioids) are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain. Discontinue all other around-the-clock opioid drugs upon initiation of morphine; naltrexone.
    NOTE: The 100 mg/4 mg strength of morphine; naltrexone is for use in opioid-tolerant patients only. Opioid-tolerant patients are defined as those taking, for a minimum of 1 week, >= 60 mg oral morphine daily, >= 30 mg oral oxycodone daily, >= 8 mg oral hydromorphone daily, >= 25 mg oral oxymorphone daily, >= 25 mcg transdermal fentanyl per hour, or an equivalent dose of another opioid.
    For use as the first opioid analgesic or in patients who are not opioid-tolerant.
    Oral dosage
    Adults

    20 mg/0.8 mg PO every 24 hours. Titrate dosage every 1 to 2 days as needed to control pain; do not dose more frequently than every 12 hours.

    For conversion from other oral morphine formulations.
    Oral dosage
    Adults

    Convert patients on other oral morphine formulations by administering the current total daily dose as morphine; naltrexone PO every 24 hours or by administering half the total daily dose every 12 hours. The first dose of morphine; naltrexone may be taken with the last dose of any short-acting opioid medication. Titrate dosage every 1 to 2 days as needed to control pain; do not dose more frequently than every 12 hours.

    For conversion from other opioid agonist analgesics.
    Oral dosage
    Adults

    30 mg/1.2 mg PO every 24 hours, or alternatively, begin with half of the estimated daily oral morphine requirement PO every 24 hours. When switching from parenteral morphine, a dose of oral morphine 3 times the daily parenteral morphine requirement may be sufficient; in general 2 to 6 mg of oral morphine may be required to provide similar analgesia as 1 mg of parenteral morphine. Use extreme caution when converting patients from methadone as the ratio between methadone and other opioid agonists can vary widely. The first dose of morphine; naltrexone may be taken with the last dose of any short-acting opioid medication. Titrate dosage every 1 to 2 days as needed to control pain; do not dose more frequently than every 12 hours.

    MAXIMUM DOSAGE

    Adults

    With appropriate dosage titration, there is no maximum dose of morphine.

    Elderly

    With appropriate dosage titration, there is no maximum dose of morphine.

    Adolescents

    Safety and efficacy have not been established.

    Children

    Safety and efficacy have not been established.

    Infants

    Safety and efficacy have not been established.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    The pharmacokinetics of morphine are altered in patients with hepatic disease; naltrexone has not been studied in such patients. Morphine; naltrexone dosage should be modified depending on clinical response and degree of hepatic impairment. No quantitative recommendations are available.

    Renal Impairment

    The 6-glucuronide metabolite of morphine is renally eliminated and significant accumulation is known to occur in patients with renal impairment; naltrexone has not been studied in such patients. Morphine; naltrexone dosage should be modified depending on clinical response and degree of renal impairment. No quantitative recommendations are available.

    ADMINISTRATION

    Oral Administration

    Administer with food or milk to minimize gastrointestinal irritation.
    Limit the use of Embeda 100 mg/4 mg to opioid tolerant patients only. 
    Do not administer through a nasogastric or gastric tube.

    Oral Solid Formulations

    Capsules must be swallowed whole or administered over applesauce. Capsules may be opened and the contents sprinkled on applesauce (at room temperature or cooler) immediately prior to ingestion; no other food has been tested. Do not chew, crush, or dissolve the pellets/beads inside the capsule. The applesauce needs to be swallowed not chewed. If the pellets/beads are broken, an immediate release of a potentially fatal morphine dose may be delivered. Rinse mouth to ensure all the pellets/beads have been swallowed. Do not separate applesauce into multiple doses; the entire portion should be taken at once.

    STORAGE

    Embeda:
    - Store at 77 degrees F; excursions permitted to 59-86 degrees F

    CONTRAINDICATIONS / PRECAUTIONS

    General Information

    NOTE: This monograph discusses a combination product of morphine and naltrexone. When morphine; naltrexone is administered as intended, the naltrexone component produces no clinically significant effect; however, after tampering (crushing or dissolving), a therapeutic dose of naltrexone is available. Naltrexone-induced opioid antagonism may occur possibly resulting in symptoms of withdrawal. In addition, potentially fatal opiate toxicity is possible if this drug combination is chewed, crushed, or dissolved prior to administration.

    Opiate agonist hypersensitivity

    Although true opiate agonist hypersensitivity is rare, use of morphine; naltrexone is contraindicated in patients with a history of morphine hypersensitivity or naltrexone hypersensitivity. Further, do not use other opioid agonists of the phenanthrene subclass including oxycodone, codeine, and hydromorphone in such patients. It may be possible to treat these patients with an opioid agonist from the phenylpiperidine subclass (meperidine or fentanyl) or the diphenylheptane subclass (methadone).

    Accidental exposure, alcoholism, ethanol ingestion, parenteral administration, potential for overdose or poisoning, requires an experienced clinician

    Like all opioid agonists, morphine; naltrexone is associated with a significant potential for overdose or poisoning; proper patient selection and counseling is recommended. Therapy requires an experienced clinician who is knowledgeable in the use of long-acting opioids for the management of chronic pain. Swallow capsules whole, or alternatively, the capsule contents may be sprinkled on applesauce. Do not crush, chew, or dissolve the capsules or the pellets within the capsules; tampering with this formulation in any manner, including crushing or dissolving, then snorting or administering via parenteral administration, may result in the release of a life-threatening dose of morphine and/or the release of a opioid withdrawal-precipitating dose of naltrexone in opioid-tolerant individuals. Morphine; naltrexone should be kept out of the reach of pediatric patients, as accidental exposure may cause a fatal overdose. Consumption with ethanol will result in additive CNS depressant effects and may lead to increased drug exposure that may cause a fatal overdose. Advise patients to avoid ethanol ingestion, including the ingestion of alcohol contained in prescription or non-prescription medications, during therapy. Patients with alcoholism should be advised of this serious risk, or an alternative medication should be used.

    Depression, substance abuse

    Morphine is an opioid agonist and therefore has abuse potential and risk of fatal overdose from respiratory failure. Addiction may occur in patients who obtain morphine; naltrexone illicitly or in those appropriately prescribed the drug. The risk of addiction in any individual is unknown. However, patients with mental illness (e.g., major depression) or a family history of substance abuse (including alcoholism) have an increased risk of opioid abuse. Assess patients for risks of addiction, abuse, or misuse before drug initiation, and monitor patients who receive opioids routinely for development of these behaviors or conditions. A potential risk of abuse should not preclude appropriate pain management in any patient, but requires more intensive counseling and monitoring. Abuse and addiction are separate and distinct from physical dependence and tolerance; patients with addiction may not exhibit tolerance and symptoms of physical dependence. The misuse of tablets by crushing, chewing, snorting, or injecting the dissolved product will result in uncontrolled morphine delivery and can result in overdose and death; naltrexone release may also precipitate withdrawal in physically dependent patients. To discourage abuse, the smallest appropriate quantity of morphine; naltrexone should be dispensed, and proper disposal instructions for unused drug should be given to patients.

    Asthma, bronchitis, chronic obstructive pulmonary disease (COPD), coadministration with other CNS depressants, cor pulmonale, emphysema, hypoxemia, obesity, pulmonary disease, respiratory depression, respiratory insufficiency, scoliosis, sleep apnea, status asthmaticus

    Use appropriate caution when considering opioid therapy in patients with respiratory impairment. Additionally, avoid coadministration with other CNS depressants unless no other alternatives are available, as this significantly increases the risk for respiratory depression, low blood pressure, and death. Morphine; naltrexone is contraindicated for use in patients with significant respiratory depression and/or acute or severe bronchial asthma (e.g., status asthmaticus) in unmonitored settings or in the absence of resuscitative equipment. Receipt of moderate morphine doses in these patients may significantly decrease pulmonary ventilation. Respiratory depression, if left untreated, may cause respiratory arrest and death. Symptoms of respiratory depression include a reduced urge to breathe, a decreased respiratory rate, or deep breaths separated by long pauses (a "sighing" breathing pattern). Carbon dioxide retention from respiratory depression may also worsen opioid sedating effects. Only healthcare professionals who are knowledgeable of the use of opioids for the management of chronic pain should prescribe morphine; naltrexone. The extended-release capsules should be reserved for patients in whom alternative treatment options (e.g., non-opioid analgesics or immediate-release opioids) are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain. Do not use extended-release capsules as a "prn" or "as needed" analgesic, for acute pain, or if the pain is mild or not expected to persist for an extended period of time. Proper dosing and titration are essential; patients should be monitored for respiratory depression, particularly during the first 24—72 hours after therapy initiation or after a dose increase. Caution should be exercised when converting from a different opioid to morphine; naltrexone, as initial dose overestimation may lead to fatal overdose. In patients with pulmonary disease such as chronic obstructive pulmonary disease (COPD), cor pulmonale, decreased respiratory reserve, hypoxia or hypoxemia, hypercapnia, emphysema, chronic bronchitis, respiratory insufficiency, upper airway obstruction, or preexisting respiratory depression, it is recommended that non-opioid analgesics be considered as alternatives to morphine; naltrexone, as even usual therapeutic doses may decrease respiratory drive and cause apnea in these patient populations. Extreme caution should also be used in patients with chronic asthma, kyphoscoliosis (a type of scoliosis), or paralysis of the phrenic nerve. Patients with advanced age, debilitation, or sleep apnea are at an increased risk for the development of respiratory depression associated with morphine. Use with caution in patients with obesity as this is a risk factor for obstructive sleep-apnea syndrome and/or decreased respiratory reserve. If treatment of respiratory depression in an individual physically dependent on opioids is necessary, administer the opioid antagonist with extreme care; titrate the antagonist dose by using smaller than usual doses. A high level of vigilant monitoring is recommended and supportive care should be given as needed.

    Opioid-naive patients

    Do not use morphine; naltrexone 100mg/4mg in opioid-naive patients. Administration may cause fatal respiratory depression in patients not already tolerant to high-dose opioids. Further, morphine; naltrexone is only indicated for management of pain severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate; do not use this product as an as-needed analgesic.

    MAOI therapy

    Use of morphine; naltrexone is contraindicated in patients who are receiving or have received MAOI therapy within the past 14 days. Additive CNS depression, drowsiness, dizziness, or hypotension may occur.

    Abrupt discontinuation

    Abrupt discontinuation of prolonged morphine; naltrexone therapy can result in opioid withdrawal symptoms. Gradually reduce the dose every 2—4 days to prevent signs and symptoms of withdrawal in the physically-dependent patient. Avoid use of mixed agonist/antagonists (e.g., nalbuphine) or pure antagonists (e.g., naloxone) in patients physically dependent on opioids. The severity of the withdrawal syndrome produced will depend on the degree of physical dependence and on the administered dose of the concomitant drug. If treatment of respiratory depression in an individual physically dependent on opioids is necessary, administer the opioid antagonist with extreme care; titrate the antagonist dose by using smaller than usual doses. Additionally, use of partial agonists or mixed agonist/antagonists in patients who have received or are receiving morphine; naltrexone may reduce the analgesic effect. While morphine; naltrexone contains the opioid antagonist naltrexone, when used appropriately, it is not intended to exert a clinically significant effect. Consumption of capsules that have been altered by chewing, crushing, or dissolving the pellets within the capsule may release enough naltrexone to precipitate withdrawal. Symptoms may appear as early as 5 minutes following ingestion and may last for up to 2 days.

    Dental work, surgery

    Discontinue morphine; naltrexone 24 hours before scheduled cordotomy or other surgery for the interruption of pain transmission pathways; use short-acting opioids for pain management. Following such a procedure, individualized titration of analgesics is needed. Patients who are taking morphine; naltrexone as part of ongoing analgesia therapy may be safely continued on the drug following other (non-pain management) surgeries or dental work, if appropriate dosage adjustments are made considering the procedure, other drugs given, and temporary changes in physiology caused by the surgical intervention. Monitor for decreased bowel motility in postoperative patients receiving opiate agonists.

    Acute abdomen, constipation, diarrhea, gastroparesis, GI disease, GI obstruction, ileus, inflammatory bowel disease, ulcerative colitis

    Morphine; naltrexone is contraindicated in patients with known or suspected GI obstruction, including paralytic ileus. Due to the effects of opiate agonists on the gastrointestinal tract, morphine should be used cautiously in patients with GI disease such as ulcerative colitis (UC). Patients with UC or other inflammatory bowel disease may be more sensitive to constipation caused by opiate agonists. Patients with short-term or intermittent gastroparesis may have an increased risk of an uncontrolled bolus release of morphine if normal gut motility returns, thus allowing morphine absorption from previously retained products. Opiate agonists may obscure the diagnosis or clinical course in patients with an acute abdomen. Although opiate agonists are not desirable for use in patients with diarrhea secondary to poisoning or infectious diarrhea, antimotility agents have been used successfully in these patients. Morphine absorption may be lower than expected in patients with rapid GI motility. If possible, opiate agonists should not be given until the toxic substance has been eliminated.

    Biliary tract disease, pancreatitis

    Morphine and opiate agonists increase the tone of the biliary tract causing spasms (especially in the sphincter of Oddi) increasing biliary tract pressure. Biliary effects of morphine may result in plasma amylase and lipase concentrations to 2—15 times the normal values. Morphine; naltrexone should be used cautiously in patients with biliary tract disease, including acute pancreatitis, or in those undergoing biliary tract surgery.

    CNS depression, coma, head trauma, increased intracranial pressure, intracranial mass, psychosis, seizure disorder

    Morphine; naltrexone should not be used in patients with impaired consciousness or coma. Morphine; naltrexone should be used with extreme caution in patients with CNS depression, head trauma, increased intracranial pressure (ICP), intracranial mass, or toxic psychosis. Opiate agonists can compromise the evaluation of neurologic parameters. Use may transiently elevate intracranial pressure and reduce cerebral perfusion pressures. These events are associated with opiate-induced lowering of mean arterial pressure, which stimulates a regulatory response to increase cerebral blood flow leading to increased ICP. Opiate agonist-induced respiratory depression can produce cerebral hypoxia and raise CSF pressure, which is unrelated to but may exaggerate the injury. Use caution in patients with preexisting seizure disorder. Opiate analgesics, especially in high doses, can precipitate seizures.

    Adrenal insufficiency, hypothyroidism, myxedema

    Use morphine; naltrexone with caution in patients with adrenal insufficiency (i.e., Addison's disease), hypothyroidism, or myxedema. Such patients may be at increased risk of adverse events. Opioids inhibit the secretion of adrenocorticotropic hormone (ACTH), cortisol, and luteinizing hormone (LH); however, the thyroid stimulating hormone may be either stimulated or inhibited by opioids. Rarely, adrenal insufficiency has been reported in association with opioid use. Patients should seek immediate medical attention if they experience symptoms such as nausea, vomiting, loss of appetite, fatigue, weakness, dizziness, or hypotension. If adrenocortical insufficiency is suspected, confirm with diagnostic testing as soon as possible. If diagnosed, the patient should be treated with physiologic replacement doses of corticosteroids, and if appropriate, weaned off of opioid therapy. If the opioid can be discontinued, a follow-up assessment of adrenal function should be performed to determine if corticosteroid treatment can be discontinued. Other opioids may be tried; some cases reported use of a different opioid with no recurrence of adrenocortical insufficiency. It is unclear which, if any, opioids are more likely to cause adrenocortical insufficiency. In addition, chronic opioid use may lead to symptoms of hypogonadism, resulting from changes in the hypothalamic-pituitary-gonadal axis. Monitor patients for symptoms of opioid-induced endocrinopathy, particularly those receiving a daily dose equivalent to 100 mg or more of morphine. Patients presenting with signs or symptoms of androgen deficiency should undergo laboratory evaluation.

    Angina, cardiac arrhythmias, cardiac disease, heart failure, hypotension, hypovolemia, orthostatic hypotension, shock, syncope

    Morphine and other opiate agonists produce cholinergic side effects (by stimulating medullary vagal nuclei) causing bradycardia and induce the release of histamine causing peripheral vasodilation. Use morphine; naltrexone with extreme caution, if at all, in patients whose ability to maintain blood pressure has already been compromised by hypovolemia or administration of certain CNS depressant medications such as phenothiazines or general anesthetics. Monitor patients for hypotension at the initiation of therapy and during dose titration. Avoid use in circulatory shock, as morphine; naltrexone may further lower blood pressure and cardiac output. Bradycardia and vasodilation can cause problems in patients with cardiac disease (e.g., angina, heart failure). Morphine; naltrexone should be used cautiously in patients with cardiac arrhythmias or hypotension. Use caution in patients with a history of orthostatic hypotension, as opiate agonists can induce vasovagal syncope or orthostatic hypotension.

    Bladder obstruction, prostatic hypertrophy, renal disease, urethral stricture

    Use morphine; naltrexone with caution in patients with bladder obstruction, prostatic hypertrophy, urethral stricture, pelvic malignancy, or renal disease as morphine-induced tension of the detrusor muscle is more likely to cause urinary retention and oliguria in such patients.

    Hepatic disease, renal impairment

    Morphine accumulation or prolonged duration of action can occur in patients with renal impairment or hepatic disease; use morphine; naltrexone with caution in such patients. In acute situations, patients require close monitoring to avoid excessive toxicity. Patients with chronic liver or renal disease may require less frequent dosing intervals.

    Driving or operating machinery

    Any patient receiving an opiate agonist (such as morphine contained in morphine; naltrexone) should be warned about the possibility of sedation and to use caution when driving or operating machinery.

    Children

    Morphine; naltrexone has not been studied in patients less than 18 years of age; use is not recommended in children. Consider other morphine formulations, particularly short-acting products, in this patient population.

    Geriatric

    Use morphine; naltrexone with caution in geriatric or debilitated patients. Geriatric or debilitated patients are more susceptible to adverse reactions, especially sedation and respiratory depression, probably as a result of altered distribution of the drug and decreased elimination. Initial dosages may need to be reduced and dosages should be carefully titrated taking into account analgesic effects, adverse reactions, and concomitant drugs that may depress respiration.

    Labor, neonatal opioid withdrawal syndrome, neonates, obstetric delivery, pregnancy

    Morphine; naltrexone is classified as FDA pregnancy category C. There have been no adequate and well-controlled studies of morphine; naltrexone in pregnant women; however, retrospective and animal data for morphine are available. Morphine readily crosses the placenta. In animal studies, maternally toxic parenteral doses of morphine administered in the second trimester resulted in teratogenic damage in neurological, soft tissue, and skeletal systems. Third trimester exposure in rats and hamsters is associated with reversibly decreased brain, spinal cord, genital, and total body weights in offspring, as well as, delayed growth and maturation, and decreased fertility in both male and female offspring. Morphine; naltrexone is an extended release formulation of morphine not intended for short-term or as-needed dosing and is not indicated for use during labor or obstetric delivery. Further, prolonged maternal use of long-acting opioids, such as morphine; naltrexone, during pregnancy may result in neonatal opioid withdrawal syndrome (NOWS). This syndrome can be life-threatening. Severe symptoms may require pharmacologic therapy managed by clinicians familiar with neonatal opioid withdrawal. Monitor the neonate for withdrawal symptoms including irritability, hyperactivity, abnormal sleep pattern, high-pitched crying, tremor, vomiting, diarrhea, and failure to gain weight. Onset, duration, and severity of opioid withdrawal may vary based on the specific opioid used, duration of use, timing and amount of last maternal use, and rate of elimination by the newborn. Neonates whose mothers have been taking morphine chronically are frequently born small for gestational age, have decreased respiratory drive, and are at an increased risk of sudden infant death syndrome (SIDS). These newborns may show some respiratory depression and/or withdrawal symptoms at birth or within a few days. The risk of respiratory and CNS depression is especially important for premature infants, who are particularly sensitive.

    Breast-feeding

    According to the manufacturer, caution is needed if morphine; naltrexone is administered to a breast-feeding woman. Morphine is excreted in the maternal milk, and the milk to plasma morphine AUC ratio is about 2.5:1. The American Academy of Pediatrics (AAP) notes that some infants have been reported to have measurable serum morphine concentrations; however, the AAP lists morphine as a maternal medication usually compatible with breast-feeding, particularly in short-term post-partum use , due to a lack of data regarding symptoms in exposed infants. Morphine; naltrexone is not used for acute pain control or "as needed" dosing. During long-term maternal use of morphine for chronic pain, it is recommended to discontinue nursing, or discontinue the drug, taking into account the importance of the drug to the mother. Withdrawal symptoms may occur in infants whose mothers discontinue chronic opioid therapy. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.

    ADVERSE REACTIONS

    Severe

    cholecystitis / Delayed / 0-1.0
    pancreatitis / Delayed / 0-1.0
    seizures / Delayed / Incidence not known
    GI obstruction / Delayed / Incidence not known
    ileus / Delayed / Incidence not known
    neonatal opioid withdrawal syndrome / Delayed / Incidence not known
    biliary obstruction / Delayed / Incidence not known
    cardiac arrest / Early / Incidence not known
    bradycardia / Rapid / Incidence not known
    anaphylactoid reactions / Rapid / Incidence not known
    SIADH / Delayed / Incidence not known
    serotonin syndrome / Delayed / Incidence not known

    Moderate

    depression / Delayed / 0-9.9
    peripheral edema / Delayed / 1.0-9.9
    dyspnea / Early / 0-1.0
    euphoria / Early / 0-1.0
    confusion / Early / 0-1.0
    memory impairment / Delayed / 0-1.0
    hallucinations / Early / 0-1.0
    withdrawal / Early / 0-1.0
    elevated hepatic enzymes / Delayed / 0-1.0
    orthostatic hypotension / Delayed / 0-1.0
    hypotension / Rapid / 0-1.0
    blurred vision / Early / 0-1.0
    urinary retention / Early / 0-1.0
    dysuria / Early / 0-1.0
    impotence (erectile dysfunction) / Delayed / 0-1.0
    constipation / Delayed / 7.0
    tolerance / Delayed / Incidence not known
    respiratory depression / Rapid / Incidence not known
    dysphoria / Early / Incidence not known
    psychosis / Early / Incidence not known
    psychological dependence / Delayed / Incidence not known
    physiological dependence / Delayed / Incidence not known
    hyperamylasemia / Delayed / Incidence not known
    gastritis / Delayed / Incidence not known
    hypertension / Early / Incidence not known
    palpitations / Early / Incidence not known
    sinus tachycardia / Rapid / Incidence not known
    hyponatremia / Delayed / Incidence not known
    hypothyroidism / Delayed / Incidence not known
    infertility / Delayed / Incidence not known
    adrenocortical insufficiency / Delayed / Incidence not known
    myoclonia / Delayed / Incidence not known
    hyperalgesia / Delayed / Incidence not known

    Mild

    flushing / Rapid / 0-10.0
    abdominal pain / Early / 0-10.0
    pruritus / Rapid / 0-10.0
    headache / Early / 1.0-9.9
    restlessness / Early / 1.0-9.9
    anxiety / Delayed / 1.0-9.9
    dizziness / Early / 1.0-9.9
    tremor / Early / 1.0-9.9
    diarrhea / Early / 1.0-9.9
    anorexia / Delayed / 1.0-9.9
    dyspepsia / Early / 1.0-9.9
    flatulence / Early / 1.0-9.9
    vomiting / Early / 1.0-9.9
    hyperhidrosis / Delayed / 1.0-9.9
    xerostomia / Early / 1.0-9.9
    irritability / Delayed / 1.0-9.9
    chills / Rapid / 1.0-9.9
    fatigue / Early / 1.0-9.9
    lethargy / Early / 1.0-9.9
    arthralgia / Delayed / 1.0-9.9
    paresthesias / Delayed / 0-1.0
    rash / Early / 0-1.0
    gooseflesh / Early / 0-1.0
    malaise / Early / 0-1.0
    diaphoresis / Early / 0-1.0
    asthenia / Delayed / 0-1.0
    rhinorrhea / Early / 0-1.0
    weakness / Early / 0-1.0
    myalgia / Early / 0-1.0
    drowsiness / Early / 10.0
    nausea / Early / 10.0
    miosis / Early / 10.0
    syncope / Early / Incidence not known
    amenorrhea / Delayed / Incidence not known
    gonadal suppression / Delayed / Incidence not known
    libido decrease / Delayed / Incidence not known

    DRUG INTERACTIONS

    Acetaminophen; Butalbital: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Acetaminophen; Butalbital; Caffeine: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Acetaminophen; Butalbital; Caffeine; Codeine: (Major) Concomitant use of morphine with codeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or codeine is recommended; for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression. (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Acetaminophen; Caffeine; Dihydrocodeine: (Major) Concomitant use of morphine with dihydrocodeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or dihydrocodeine is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Acetaminophen; Caffeine; Magnesium Salicylate; Phenyltoloxamine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Acetaminophen; Caffeine; Phenyltoloxamine; Salicylamide: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Acetaminophen; Chlorpheniramine; Phenylephrine; Phenyltoloxamine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Acetaminophen; Codeine: (Major) Concomitant use of morphine with codeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or codeine is recommended; for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Acetaminophen; Diphenhydramine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Acetaminophen; Hydrocodone: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression.
    Acetaminophen; Oxycodone: (Major) Concomitant use of oxycodone with morphine may lead to additive respiratory and/or CNS depression. Hypotension, profound sedation, coma, respiratory depression, or death may occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of oxycodone and/or morphine is recommended; use an initial dose of oxycodone at one-third to one-half the usual dosage. For extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor for sedation and respiratory depression.
    Acetaminophen; Pentazocine: (Major) Avoid the concomitant use of pentazocine and opiate agonists, such as morphine. Pentazocine is a mixed opiate agonist/antagonist that may block the effects of opiate agonists and reduce analgesic effects of morphine. Pentazocine may cause withdrawal symptoms in patients receiving chronic opiate agonists. Concurrent use of pentazocine with other opiate agonists can cause additive CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist.
    Acetaminophen; Tramadol: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and tramadol. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and tramadol should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated. Lastly, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Acrivastine; Pseudoephedrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Adefovir: (Moderate) Adefovir is eliminated renally by a combination of glomerular filtration and active tubular secretion; coadministration of adefovir dipivoxil with drugs that reduce renal function or compete for active tubular secretion, such as morphine, may decrease adefovir elimination by competing for common renal tubular transport systems, therefore increasing serum concentrations of either adefovir and/or these coadministered drugs.
    Aldesleukin, IL-2: (Moderate) Aldesleukin, IL-2 may affect CNS function significantly. Therefore, psychotropic pharmacodynamic interactions could occur following concomitant administration of drugs with significant CNS or psychotropic activity such as opiate agonists. In addition, aldesleukin, IL-2, is a CYP3A4 inhibitor and may increase oxycodone plasma concentrations and related toxicities including potentially fatal respiratory depression. If therapy with both agents is necessary, monitor patients for an extended period and adjust oxycodone dosage as necessary.
    Alfentanil: (Major) Concomitant use of morphine with alfentanil can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. If alfentanil is used concurrently with morphine, monitor patients for sedation and respiratory depression.
    Aliskiren; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Almotriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor agonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor agonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Alosetron: (Major) Patients taking medications that decrease GI motility may be at greater risk for serious complications from alosetron, like constipation, via a pharmacodynamic interaction. Constipation is the most frequently reported adverse effect with alosetron. Alosetron, if used with drugs such as opiate agonists, may seriously worsen constipation, leading to events such as GI obstruction/impaction or paralytic ileus.
    Alprazolam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Alvimopan: (Moderate) Patients should not take alvimopan if they have received therapeutic doses of opiate agonists for more than seven consecutive days immediately before initiation of alvimopan therapy. Patients recently exposed to opioids are expected to be more sensitive to the effects of mu-opioid receptor antagonists and may experience adverse effects localized to the gastrointestinal tract such as abdominal pain, nausea, vomiting, and diarrhea.
    Amide local anesthetics: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Amiloride: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction.
    Amiloride; Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Amitriptyline: (Major) Concomitant use of morphine with other CNS depressants, such as tricyclic antidepressants (TCAs), can potentiate the effects of morphine on respiration, blood pressure, and alertness. Use may cause profound sedation, hypotension, hypoventilation, or coma. Orthostasis may occur in ambulatory patients. Additive effects such as constipation may also occur. Prior to concurrent use of morphine in patients taking a TCA, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a TCA is used concurrently with morphine, usually, a reduced initial dosage of morphine is to be considered. For example, for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). A reduced dosage of the TCA may also be necessary. Monitor patients for sedation, hypotension, reduced GI motility, and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering TCAs with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the TCA should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Amitriptyline; Chlordiazepoxide: (Major) Concomitant use of morphine with other CNS depressants, such as tricyclic antidepressants (TCAs), can potentiate the effects of morphine on respiration, blood pressure, and alertness. Use may cause profound sedation, hypotension, hypoventilation, or coma. Orthostasis may occur in ambulatory patients. Additive effects such as constipation may also occur. Prior to concurrent use of morphine in patients taking a TCA, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a TCA is used concurrently with morphine, usually, a reduced initial dosage of morphine is to be considered. For example, for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). A reduced dosage of the TCA may also be necessary. Monitor patients for sedation, hypotension, reduced GI motility, and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering TCAs with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the TCA should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated. (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Amlodipine; Hydrochlorothiazide, HCTZ; Olmesartan: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Amlodipine; Hydrochlorothiazide, HCTZ; Valsartan: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Amobarbital: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Amoxapine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include amoxapine. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Anticholinergics: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Apomorphine: (Moderate) Apomorphine causes significant somnolence. Concomitant administration of apomorphine and CNS depressants could result in additive depressant effects.
    Apraclonidine: (Minor) Theoretically, apraclonidine might potentiate the effects of CNS depressant drugs such as opiate agonists. Although no specific drug interactions were identified with systemic agents and apraclonidine during clinical trials, apraclonidine can cause dizziness and somnolence.
    Articaine; Epinephrine: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Asenapine: (Moderate) Drugs that can cause CNS depression, if used concomitantly with asenapine, may increase both the frequency and the intensity of adverse effects such as drowsiness, sedation, and dizziness. Caution should be used when asenapine is given in combination with other centrally-acting medications including opiate agonists.
    Aspirin, ASA; Butalbital; Caffeine: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Aspirin, ASA; Butalbital; Caffeine; Codeine: (Major) Concomitant use of morphine with codeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or codeine is recommended; for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression. (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Aspirin, ASA; Caffeine; Dihydrocodeine: (Major) Concomitant use of morphine with dihydrocodeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or dihydrocodeine is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Aspirin, ASA; Carisoprodol: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Aspirin, ASA; Carisoprodol; Codeine: (Major) Concomitant use of morphine with codeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or codeine is recommended; for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression. (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Aspirin, ASA; Oxycodone: (Major) Concomitant use of oxycodone with morphine may lead to additive respiratory and/or CNS depression. Hypotension, profound sedation, coma, respiratory depression, or death may occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of oxycodone and/or morphine is recommended; use an initial dose of oxycodone at one-third to one-half the usual dosage. For extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor for sedation and respiratory depression.
    Atazanavir; Cobicistat: (Moderate) The plasma concentrations of morphine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as oversedation, respiratory depression, and hypotension, is recommended during coadministration. Cobicistat is a P-glycoprotein (P-gp) inhibitor, while morphine is a P-gp substrate.
    Atenolol; Chlorthalidone: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Atracurium: (Moderate) Concomitant use of morphine with other CNS depressants, such as neuromuscular blockers, can potentiate the effects of morphine on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
    Atropine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Atropine; Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Severe) Morphine use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Methylene blue is a reversible inhibitor of MAO. Concomitant use of morphine with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as morphine. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Atropine; Difenoxin: (Major) Concurrent administration of diphenoxylate/difenoxin with other opiate agonists can potentiate the CNS-depressant effects of diphenoxylate/difenoxin. Use caution during coadministration. In addition, diphenoxylate/difenoxin use may cause constipation; cases of severe GI reactions including toxic megacolon and adynamic ileus have been reported. Reduced GI motility when combined with opiate agonists may increase the risk of serious GI related adverse events. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Atropine; Diphenoxylate: (Major) Concurrent administration of diphenoxylate/difenoxin with other opiate agonists can potentiate the CNS-depressant effects of diphenoxylate/difenoxin. Use caution during coadministration. In addition, diphenoxylate/difenoxin use may cause constipation; cases of severe GI reactions including toxic megacolon and adynamic ileus have been reported. Reduced GI motility when combined with opiate agonists may increase the risk of serious GI related adverse events. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Atropine; Edrophonium: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Atropine; Hyoscyamine; Phenobarbital; Scopolamine: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Azelastine: (Moderate) An enhanced CNS depressant effect may occur when azelastine is combined with other CNS depressants including opiate agonists. A dose reduction of one or both drugs may be warranted.
    Azelastine; Fluticasone: (Moderate) An enhanced CNS depressant effect may occur when azelastine is combined with other CNS depressants including opiate agonists. A dose reduction of one or both drugs may be warranted.
    Azilsartan; Chlorthalidone: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Baclofen: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Barbiturates: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Belladonna Alkaloids; Ergotamine; Phenobarbital: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Belladonna; Opium: (Major) Concomitant use of morphine with opium can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or opium is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Bendroflumethiazide; Nadolol: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Severe) Morphine use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Methylene blue is a reversible inhibitor of MAO. Concomitant use of morphine with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as morphine. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Benztropine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Bethanechol: (Moderate) Bethanechol facilitates intestinal and bladder function via parasympathomimetic actions. Opiate agonists impair the peristaltic activity of the intestine. Thus, these drugs can antagonize the beneficial actions of bethanechol on GI motility.
    Bismuth Subcitrate Potassium; Metronidazole; Tetracycline: (Moderate) Additive constipation may be seen with concurrent use of opiate agonists and antidiarrheals. Opioids increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Bismuth Subsalicylate: (Moderate) Additive constipation may be seen with concurrent use of opiate agonists and antidiarrheals. Opioids increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Bismuth Subsalicylate; Metronidazole; Tetracycline: (Moderate) Additive constipation may be seen with concurrent use of opiate agonists and antidiarrheals. Opioids increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Boceprevir: (Moderate) Close clinical monitoring is advised when administering morphine with boceprevir due to an increased potential for morphine-related adverse events. If morphine dose adjustments are made, re-adjust the dose upon completion of boceprevir treatment. Although this interaction has not been studied, predictions about the interaction can be made based on the metabolic pathway of morphine. Morphine is a substrate of the drug efflux transporter P-glycoprotein (P-gp); boceprevir is an inhibitor of this efflux protein. Coadministration may result in elevated morphine plasma concentrations.
    Brexpiprazole: (Moderate) Due to the CNS effects of brexpiprazole, caution is advisable when brexpiprazole is given in combination with other centrally-acting medications including opiate agonists.
    Brimonidine: (Moderate) Based on the sedative effects of brimonidine in individual patients, brimonidine administration has potential to enhance the CNS depressants effects of opiate agonists.
    Brimonidine; Brinzolamide: (Moderate) Based on the sedative effects of brimonidine in individual patients, brimonidine administration has potential to enhance the CNS depressants effects of opiate agonists.
    Brimonidine; Timolol: (Moderate) Based on the sedative effects of brimonidine in individual patients, brimonidine administration has potential to enhance the CNS depressants effects of opiate agonists.
    Brompheniramine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Brompheniramine; Carbetapentane; Phenylephrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Brompheniramine; Dextromethorphan; Guaifenesin: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Brompheniramine; Guaifenesin; Hydrocodone: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Brompheniramine; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Brompheniramine; Pseudoephedrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Bumetanide: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction.
    Bupivacaine Liposomal: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Bupivacaine: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Bupivacaine; Lidocaine: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Buprenorphine: (Major) Buprenorphine is a mixed opiate agonist/antagonist with strong affinity for the mu-receptor that may partially block the effects of full mu-receptor opiate agonists and reduce analgesic effects. In some cases of acute pain, trauma, or during surgical management, opiate-dependent patients receiving buprenorphine maintenance therapy may require concurrent treatment with opiate agonists, such as morphine. In these cases, health care professionals must exercise caution in opiate agonist dose selection, as higher doses of an opiate agonist may be required to compete with buprenorphine at the mu-receptor. Management strategies may include adding a short-acting opiate agonist to achieve analgesia in the presence of buprenorphine, discontinuation of buprenorphine and use of an opiate agonist to avoid withdrawal and achieve analgesia, or conversion of buprenorphine to methadone while using additional opiate agonists if needed. Closely monitor patients for CNS or respiratory depression. When buprenorphine is used for analgesia, avoid co-use with opiate agonists. Buprenorphine may cause withdrawal symptoms in patients receiving chronic opiate agonists as well as possibly potentiate CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist.
    Buprenorphine; Naloxone: (Major) Buprenorphine is a mixed opiate agonist/antagonist with strong affinity for the mu-receptor that may partially block the effects of full mu-receptor opiate agonists and reduce analgesic effects. In some cases of acute pain, trauma, or during surgical management, opiate-dependent patients receiving buprenorphine maintenance therapy may require concurrent treatment with opiate agonists, such as morphine. In these cases, health care professionals must exercise caution in opiate agonist dose selection, as higher doses of an opiate agonist may be required to compete with buprenorphine at the mu-receptor. Management strategies may include adding a short-acting opiate agonist to achieve analgesia in the presence of buprenorphine, discontinuation of buprenorphine and use of an opiate agonist to avoid withdrawal and achieve analgesia, or conversion of buprenorphine to methadone while using additional opiate agonists if needed. Closely monitor patients for CNS or respiratory depression. When buprenorphine is used for analgesia, avoid co-use with opiate agonists. Buprenorphine may cause withdrawal symptoms in patients receiving chronic opiate agonists as well as possibly potentiate CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist. (Major) Naloxone can antagonize the therapeutic efficacy of morphine in addition to precipitating withdrawal symptoms in patients who are physically dependent on opiate drugs including morphine. Naloxone should not be administered in the absence of clinically significant respiratory or circulatory depression secondary to morphine overdose.
    Bupropion: (Moderate) Excessive use of opioid agonists (e.g., opiate addiction) is associated with an increased seizure risk; seizures may be more likely to occur during concurrent use of bupropion in these patients since bupropion is associated with a dose-related risk of seizures.
    Bupropion; Naltrexone: (Major) When naltrexone is used as adjuvant treatment of opiate or alcohol dependence, use is contraindicated in patients currently receiving opiate agonists. Naltrexone will antagonize the therapeutic benefits of opiate agonists and will induce a withdrawal reaction in patients with physical dependence to opioids. Also, patients should be opiate-free for at least 7 to 10 days prior to initiating naltrexone therapy. If there is any question of opioid use in the past 7 to 10 days and the patient is not experiencing opioid withdrawal symptoms and/or the urine is negative for opioids, a naloxone challenge test needs to be performed. If a patient receives naltrexone, and an opiate agonist is needed for an emergency situation, large doses of opiate agonists may ultimately overwhelm naltrexone antagonism of opiate receptors. Immediately following administration of exogenous opiate agonists, the opiate plasma concentration may be sufficient to overcome naltrexone competitive blockade, but the patient may experience deeper and more prolonged respiratory depression and thus, may be in danger of respiratory arrest and circulatory collapse. Non-receptor mediated actions like facial swelling, itching, generalized erythema, or bronchoconstriction may occur presumably due to histamine release. A rapidly acting opiate agonist is preferred as the duration of respiratory depression will be shorter. Patients receiving naltrexone may also experience opiate side effects with low doses of opiate agonists. If the opiate agonist is taken in such a way that high concentrations remain in the body beyond the time naltrexone exerts its therapeutic effects, serious side effects may occur. (Moderate) Excessive use of opioid agonists (e.g., opiate addiction) is associated with an increased seizure risk; seizures may be more likely to occur during concurrent use of bupropion in these patients since bupropion is associated with a dose-related risk of seizures.
    Buspirone: (Moderate) Concomitant use of CNS depressants, such as buspirone, can potentiate the effects of morphine, which may potentially lead to respiratory depression, CNS depression, sedation, or hypotensive responses. If concurrent use of morphine and buspirone is imperative, reduce the dose of one or both drugs.
    Butabarbital: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Butorphanol: (Major) Avoid the concomitant use of butorphanol and opiate agonists, such as morphine. Butorphanol is a mixed opiate agonist/antagonist that may block the effects of opiate agonists and reduce analgesic effects. Butorphanol may cause withdrawal symptoms in patients receiving chronic opiate agonists. Concurrent use of butorphanol with other opiate agonists can cause additive CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist.
    Cabozantinib: (Minor) Monitor for an increase in morphine-related adverse reactions, including hypotension, sedation, and respiratory depression, if coadministration with cabozantinib is necessary; a dose adjustment of morphine may be necessary. Morphine is a P-glycoprotein (P-gp) substrate. Cabozantinib is a P-gp inhibitor and has the potential to increase plasma concentrations of P-gp substrates; however, the clinical relevance of this finding is unknown. Coadministration with P-gp inhibitors can increase morphine exposure by about 2-fold.
    Candesartan; Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Cannabidiol: (Moderate) Concomitant use of opioid agonists with cannabidiol may cause excessive sedation and somnolence. Limit the use of opioid pain medications with cannabidiol to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking cannabidiol, reduce initial dosage and titrate to clinical response. If cannabidiol is initiated in a patient taking morphine, use a lower initial dose of cannabidiol and titrate to clinical response. Educate patients about the risks and symptoms of excessive CNS depression. In addition, morphine is a UGT2B7 substrate. In vitro data predicts inhibition of UGT2B7 by cannabidiol potentially resulting in clinically significant interactions.
    Capsaicin; Metaxalone: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Captopril; Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Carbetapentane; Chlorpheniramine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Chlorpheniramine; Phenylephrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Diphenhydramine; Phenylephrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Guaifenesin: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Guaifenesin; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Phenylephrine; Pyrilamine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Pseudoephedrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Pyrilamine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbidopa; Levodopa; Entacapone: (Moderate) Concomitant use of opiate agonists with other central nervous system (CNS) depressants such as COMT inhibitors can potentiate the effects of the opiate and may lead to additive CNS or respiratory depression, profound sedation, or coma. Prior to concurrent use of an opiate in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If these agents are used together, a reduced dosage of the opiate and/or the CNS depressant is recommended. Carefully monitor the patient for hypotension, CNS depression, and respiratory depression. Carbon dioxide retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids.
    Carbinoxamine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Carbinoxamine; Dextromethorphan; Pseudoephedrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Carbinoxamine; Hydrocodone; Phenylephrine: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Carbinoxamine; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Carbinoxamine; Phenylephrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Carbinoxamine; Pseudoephedrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Cariprazine: (Moderate) Due to the CNS effects of cariprazine, caution is advisable when cariprazine is given in combination with other centrally-acting medications including opiate agonists.
    Carisoprodol: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Carvedilol: (Moderate) Increased concentrations of morphine may occur if it is coadministered with carvedilol; exercise caution. Carvedilol is a P-glycoprotein (P-gp) inhibitor and morphine is a P-gp substrate.
    Cetirizine: (Moderate) Additive drowsiness may occur if cetirizine or levocetirizine is administered with other drugs that depress the CNS, including opiate agonists.
    Cetirizine; Pseudoephedrine: (Moderate) Additive drowsiness may occur if cetirizine or levocetirizine is administered with other drugs that depress the CNS, including opiate agonists.
    Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorcyclizine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlordiazepoxide: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Chlordiazepoxide; Clidinium: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Chloroprocaine: (Minor) Due to the central nervous system depression potential of local anesthetics, they should be used with caution with other agents that can cause respiratory depression, such as opiate agonists.
    Chlorothiazide: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Chlorpheniramine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpheniramine; Codeine: (Major) Concomitant use of morphine with codeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or codeine is recommended; for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpheniramine; Dextromethorphan: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Major) Concomitant use of morphine with dihydrocodeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or dihydrocodeine is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpheniramine; Dihydrocodeine; Pseudoephedrine: (Major) Concomitant use of morphine with dihydrocodeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or dihydrocodeine is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpheniramine; Guaifenesin; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpheniramine; Hydrocodone: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpheniramine; Hydrocodone; Phenylephrine: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpheniramine; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpheniramine; Phenylephrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpheniramine; Pseudoephedrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Chlorpromazine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Severe hypotension may occur if morphine is administered to a patient taking phenothiazines. Profound sedation and coma may also occur. Prior to use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules).
    Chlorthalidone: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Chlorthalidone; Clonidine: (Moderate) Clonidine has CNS depressive effects and can potentiate the actions of other CNS depressants including opiate agonists. (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Chlorzoxazone: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Cimetidine: (Moderate) Concurrent use of morphine and cimetidine may increase the adverse effects of morphine, especially if a large cimetidine dose is used or if the patient is not young and healthy. One patient undergoing hemodialysis experienced confusion and severe respiratory depression when given morphine and cimetidine concurrently. As determined by data obtained from healthy patients, the mean systemic exposure, half-life, volume of distribution, and plasma clearance of morphine were similar after 4 days of pretreatment with either placebo or cimetidine 300 mg every 6 hours by mouth. In another crossover study, the concurrent receipt of cimetidine 600 mg orally and 10 mg morphine intramuscularly by 8 healthy adults led to a more profound depression of the CO2 response and delay in its recovery as compared with only morphine receipt; cimetidine alone had negligible respiratory effects. Also, concomitant administration of morphine and cimetidine has been reported to precipitate apnea, confusion, and muscle twitching in an isolated report. Monitor patients for increased respiratory and CNS depression when receiving both cimetidine and morphine.
    Cisatracurium: (Moderate) Concomitant use of morphine with other CNS depressants, such as neuromuscular blockers, can potentiate the effects of morphine on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
    Citalopram: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering selective serotonin reuptake inhibitors (SSRIs), such as citalopram, with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and citalopram should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Clemastine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Clobazam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Clomipramine: (Major) Concomitant use of morphine with other CNS depressants, such as tricyclic antidepressants (TCAs), can potentiate the effects of morphine on respiration, blood pressure, and alertness. Use may cause profound sedation, hypotension, hypoventilation, or coma. Orthostasis may occur in ambulatory patients. Additive effects such as constipation may also occur. Prior to concurrent use of morphine in patients taking a TCA, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a TCA is used concurrently with morphine, usually, a reduced initial dosage of morphine is to be considered. For example, for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). A reduced dosage of the TCA may also be necessary. Monitor patients for sedation, hypotension, reduced GI motility, and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering TCAs with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the TCA should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Clonazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Clonidine: (Moderate) Clonidine has CNS depressive effects and can potentiate the actions of other CNS depressants including opiate agonists.
    Clopidogrel: (Moderate) Coadministration of opioid agonists delay and reduce the absorption of clopidogrel resulting in reduced exposure to active metabolites and diminished inhibition of platelet aggregation. Consider the use of a parenteral antiplatelet agent in acute coronary syndrome patients requiring an opioid agonist. Coadministration of intravenous morphine decreased the Cmax and AUC of clopidogrel's active metabolites by 34%. Time required for maximal inhibition of platelet aggregation (median 3 hours vs. 1.25 hours) was significantly delayed; times up to 5 hours were reported. Inhibition of platelet plug formation was delayed and residual platelet aggregation was significantly greater 1 to 4 hours after morphine administration.
    Clorazepate: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Clozapine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include clozapine. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Cobicistat: (Moderate) The plasma concentrations of morphine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as oversedation, respiratory depression, and hypotension, is recommended during coadministration. Cobicistat is a P-glycoprotein (P-gp) inhibitor, while morphine is a P-gp substrate.
    Cobicistat; Elvitegravir; Emtricitabine; Tenofovir Alafenamide: (Moderate) The plasma concentrations of morphine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as oversedation, respiratory depression, and hypotension, is recommended during coadministration. Cobicistat is a P-glycoprotein (P-gp) inhibitor, while morphine is a P-gp substrate.
    Cobicistat; Elvitegravir; Emtricitabine; Tenofovir Disoproxil Fumarate: (Moderate) The plasma concentrations of morphine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as oversedation, respiratory depression, and hypotension, is recommended during coadministration. Cobicistat is a P-glycoprotein (P-gp) inhibitor, while morphine is a P-gp substrate.
    Cocaine: (Minor) Due to the central nervous system depression potential of local anesthetics, they should be used with caution with other agents that can cause respiratory depression, such as opiate agonists.
    Codeine: (Major) Concomitant use of morphine with codeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or codeine is recommended; for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Codeine; Guaifenesin: (Major) Concomitant use of morphine with codeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or codeine is recommended; for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Codeine; Phenylephrine; Promethazine: (Major) Concomitant use of morphine with codeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or codeine is recommended; for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Codeine; Promethazine: (Major) Concomitant use of morphine with codeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or codeine is recommended; for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    COMT inhibitors: (Moderate) Concomitant use of opiate agonists with other central nervous system (CNS) depressants such as COMT inhibitors can potentiate the effects of the opiate and may lead to additive CNS or respiratory depression, profound sedation, or coma. Prior to concurrent use of an opiate in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If these agents are used together, a reduced dosage of the opiate and/or the CNS depressant is recommended. Carefully monitor the patient for hypotension, CNS depression, and respiratory depression. Carbon dioxide retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids.
    Conivaptan: (Moderate) Use caution when administering conivaptan and morphine concurrently. Conivaptan is an inhibitor of P-glycoprotein (P-gp). Co-administration of conivaptan with P-gp substrates, such as morphine, can increase morphine exposure leading to increased or prolonged therapeutic effects and adverse events.
    Crofelemer: (Moderate) Pharmacodynamic interactions between crofelemer and opiate agonists are theoretically possible. Crofelemer does not affect GI motility mechanisms, but does have antidiarrheal effects. Patients taking medications that decrease GI motility, such as opiate agonists, may be at greater risk for serious complications from crofelemer, such as constipation with chronic use. Use caution and monitor GI symptoms during coadministration.
    Cyclizine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Cyclobenzaprine: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Cyproheptadine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Daclatasvir: (Moderate) Systemic exposure of morphine, a P-glycoprotein (P-gp) substrate, may be increased when administered concurrently with daclatasvir, a P-gp inhibitor. Taking these drugs together could increase or prolong the therapeutic effects of morphine; monitor patients for potential adverse effects.
    Dantrolene: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Darifenacin: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when darifenacin, an anticholinergic drug for overactive bladder, is used with opiate agonists. The concomitant use of these drugs together may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. Both agents may also cause drowsiness or blurred vision, and patients should use care in driving or performing other hazardous tasks until the effects of the drugs are known.
    Darunavir; Cobicistat: (Moderate) The plasma concentrations of morphine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as oversedation, respiratory depression, and hypotension, is recommended during coadministration. Cobicistat is a P-glycoprotein (P-gp) inhibitor, while morphine is a P-gp substrate.
    Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Moderate) The plasma concentrations of morphine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as oversedation, respiratory depression, and hypotension, is recommended during coadministration. Cobicistat is a P-glycoprotein (P-gp) inhibitor, while morphine is a P-gp substrate.
    Dasabuvir; Ombitasvir; Paritaprevir; Ritonavir: (Moderate) Close clinical monitoring is advised when administering morphine with ritonavir due to an increased potential for morphine-related adverse events, including hypotension, respiratory depression, profound sedation, coma, and death. Dosage reductions of morphine and/or ritonavir may be required. Morphine is a substrate of the drug efflux transporter P-glycoprotein (P-gp); ritonavir is an inhibitor of this efflux protein. Coadministration may cause an approximate 2-fold increase in morphine exposure.
    Desflurane: (Moderate) Concurrent use with opiate agonists can decrease the minimum alveolar concentration (MAC) of desflurane needed to produce anesthesia.
    Desipramine: (Major) Concomitant use of morphine with other CNS depressants, such as tricyclic antidepressants (TCAs), can potentiate the effects of morphine on respiration, blood pressure, and alertness. Use may cause profound sedation, hypotension, hypoventilation, or coma. Orthostasis may occur in ambulatory patients. Additive effects such as constipation may also occur. Prior to concurrent use of morphine in patients taking a TCA, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a TCA is used concurrently with morphine, usually, a reduced initial dosage of morphine is to be considered. For example, for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). A reduced dosage of the TCA may also be necessary. Monitor patients for sedation, hypotension, reduced GI motility, and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering TCAs with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the TCA should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Desmopressin: (Major) Additive hyponatremic effects may be seen in patients treated with desmopressin and drugs associated with water intoxication, hyponatremia, or SIADH including opiate agonists. Use combination with caution, and monitor patients for signs and symptoms of hyponatremia.
    Desvenlafaxine: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the SNRI should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Deutetrabenazine: (Major) Concomitant use of opiate agonists with deutetrabenazine may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with deutetrabenazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking deutetrabenazine, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg every 24 hours. If deutetrabenazine is prescribed for a patient taking an opiate agonist, use a lower initial dose of deutetrabenazine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Dexchlorpheniramine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Dexmedetomidine: (Moderate) Co-administration of dexmedetomidine with opiate agonists likely to lead to an enhancement of CNS depression.
    Dexpanthenol: (Moderate) Use caution when using dexpanthenol with drugs that decrease gastrointestinal motility, such as opiate agonists, as it may decrease the effectiveness of dexpanthenol.
    Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Dextromethorphan; Quinidine: (Moderate) Morphine is a substrate for P-glycoprotein (P-gp), and quinidine is a P-gp substrate and inhibitor. Coadministration may lead to increased systemic exposure of morphine and morphine-related side effects.
    Diazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. If parental diazepam is used with an opiate agonist, reduce the opiate agonist dosage by at least 1/3. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Dicyclomine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Dienogest; Estradiol valerate: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Dihydrocodeine; Guaifenesin; Pseudoephedrine: (Major) Concomitant use of morphine with dihydrocodeine can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or dihydrocodeine is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Dimenhydrinate: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Diphenhydramine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Diphenhydramine; Hydrocodone; Phenylephrine: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Diphenhydramine; Ibuprofen: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Diphenhydramine; Naproxen: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Diphenhydramine; Phenylephrine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Dolasetron: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor antagonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor antagonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Donepezil; Memantine: (Moderate) Cationic drugs that are eliminated by renal tubular secretion, such as morphine, may compete with memantine for common renal tubular transport systems, thus possibly decreasing the elimination of one of the drugs. Although theoretical, careful patient monitoring of response to memantine and/or morphine is recommended to assess for needed dosage adjustments.
    Doxacurium: (Moderate) Concomitant use of morphine with other CNS depressants, such as neuromuscular blockers, can potentiate the effects of morphine on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
    Doxepin: (Major) Concomitant use of morphine with other CNS depressants, such as tricyclic antidepressants (TCAs), can potentiate the effects of morphine on respiration, blood pressure, and alertness. Use may cause profound sedation, hypotension, hypoventilation, or coma. Orthostasis may occur in ambulatory patients. Additive effects such as constipation may also occur. Prior to concurrent use of morphine in patients taking a TCA, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a TCA is used concurrently with morphine, usually, a reduced initial dosage of morphine is to be considered. For example, for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). A reduced dosage of the TCA may also be necessary. Monitor patients for sedation, hypotension, reduced GI motility, and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering TCAs with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the TCA should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Doxylamine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Doxylamine; Pyridoxine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Dronabinol: (Moderate) Concomitant use of opiate agonists and other CNS depressants such as dronabinol, THC may result in respiratory depression, CNS depression, and/or hypotension. Prior to concurrent use of opiate agonists in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. When concomitant treatment is necessary, reduce the dose of 1 or both drugs. When levorphanol is used with dronabinol, reduce the initial levorphanol dose by approximately 50% or more.
    Droperidol: (Major) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include droperidol. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Ethanol abuse and the use of benzodiazepines and intravenous opiates are risk factors for the development of prolonged QT syndrome in patients receiving droperidol. If droperidol is used concurrently with morphine, a reduced dosage of morphine is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Drospirenone; Estradiol: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Drospirenone; Ethinyl Estradiol: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Drospirenone; Ethinyl Estradiol; Levomefolate: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Duloxetine: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the SNRI should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Eletriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor agonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor agonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Eliglustat: (Minor) Coadministration of morphine and eliglustat may result in increased plasma concentrations of morphine. Monitor patients closely for morphine-related adverse effects including respiratory depression, and consider reducing the morphine dosage and titrating to clinical effect. Morphine is a P-glycoprotein (P-gp) substrate; eliglustat is a P-gp inhibitor.
    Eltrombopag: (Moderate) Eltrombopag is a UDP-glucuronyltransferase inhibitor. Opiate agonists are a substrate of UDP-glucuronyltransferases. The significance or effect of this interaction is not known; however, elevated concentrations of the opiate agonist is possible. Monitor patients for adverse reactions if eltrombopage is administered with an opiate agonist.
    Eluxadoline: (Major) Avoid use of eluxadoline with medications that may cause constipation, such as morphine. Opioids increase the tone and decrease the propulsive contractions of the smooth muscle within the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. Closely monitor for increased side effects if these drugs are administered together.
    Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Enflurane: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended. Monitor patients for sedation and respiratory depression.
    Entacapone: (Moderate) Concomitant use of opiate agonists with other central nervous system (CNS) depressants such as COMT inhibitors can potentiate the effects of the opiate and may lead to additive CNS or respiratory depression, profound sedation, or coma. Prior to concurrent use of an opiate in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If these agents are used together, a reduced dosage of the opiate and/or the CNS depressant is recommended. Carefully monitor the patient for hypotension, CNS depression, and respiratory depression. Carbon dioxide retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids.
    Entecavir: (Moderate) Both entecavir and morphine are secreted by active tubular secretion. In theory, coadministration of entecavir with morphine may increase the serum concentrations of either drug due to competition for the drug elimination pathway. The manufacturer of entecavir recommends monitoring for adverse effects when these drugs are coadministered.
    Eprosartan; Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Escitalopram: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering selective serotonin reuptake inhibitors (SSRIs), such as escitalopram, with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and escitalopram should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Esmolol: (Moderate) Morphine increases the steady-state blood concentrations of esmolol by 50%, although morphine blood concentrations are not affected by esmolol. Careful titration of esmolol is prudent when given with morphine.
    Estazolam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Ester local anesthetics: (Minor) Due to the central nervous system depression potential of local anesthetics, they should be used with caution with other agents that can cause respiratory depression, such as opiate agonists.
    Estradiol; Levonorgestrel: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Estradiol; Norethindrone: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Estradiol; Norgestimate: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Eszopiclone: (Moderate) Concomitant use of morphine with eszopiclone can potentiate the effects of morphine on respiration, blood pressure, and alertness. In addition, the risk of next-day psychomotor impairment is increased during co-administration of eszopiclone and other CNS depressants, which may decrease the ability to perform tasks requiring full mental alertness such as driving. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If eszopiclone is used concurrently with morphine, a reduced dosage of morphine and/or eszopiclone is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Ethacrynic Acid: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction.
    Ethanol: (Major) Alcohol is associated with CNS depression. The combined use of alcohol and CNS depressants can lead to additive CNS depression, which could be dangerous in tasks requiring mental alertness and fatal in overdose. Alcohol taken with other CNS depressants can lead to additive respiratory depression, hypotension, profound sedation, or coma. Consider the patient's use of alcohol or illicit drugs when prescribing CNS depressant medications. In many cases, the patient should receive a lower dose of the CNS depressant initially if the patient is not likely to be compliant with avoiding alcohol.
    Ethinyl Estradiol: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Desogestrel: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Ethynodiol Diacetate: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Etonogestrel: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Levonorgestrel: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Levonorgestrel; Ferrous bisglycinate: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Levonorgestrel; Folic Acid; Levomefolate: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Norelgestromin: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Norethindrone Acetate: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Norethindrone Acetate; Ferrous fumarate: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Norethindrone: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Norethindrone; Ferrous fumarate: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Norgestimate: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethinyl Estradiol; Norgestrel: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Ethotoin: (Moderate) Additive CNS depression could be seen with the combined use of the ethotoin and morphine.
    Etomidate: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended. Monitor patients for sedation and respiratory depression.
    Etravirine: (Moderate) Increased concentrations of morphine may occur if it is coadministered with etravirine; exercise caution. Etravirine is an inhibitor of the efflux transporter P-glycoprotein (P-gp). Morphine is a P-gp substrate.
    Fentanyl: (Major) Concomitant use of morphine with fentanyl can potentiate the effects of morphine on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or fentanyl is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Fesoterodine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when fesoterodine, an anticholinergic drug for overactive bladder. is used with opiate agonists. The concomitant use of these drugs together may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. Both agents may also cause drowsiness or blurred vision, and patients should use care in driving or performing other hazardous tasks until the effects of the drugs are known.
    Flavoxate: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Flibanserin: (Moderate) The concomitant use of flibanserin with CNS depressants, such as opiate agonists, may increase the risk of CNS depression (e.g., dizziness, somnolence) compared to the use of flibanserin alone. Patients should avoid activities requiring full alertness (e.g., operating machinery or driving) until at least 6 hours after each dose and until they know how flibanserin affects them.
    Fluoxetine: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and fluoxetine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Fluoxetine; Olanzapine: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and fluoxetine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include olanzapine. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Fluphenazine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Severe hypotension may occur if morphine is administered to a patient taking phenothiazines. Profound sedation and coma may also occur. Prior to use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules).
    Flurazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Fluvoxamine: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering selective serotonin reuptake inhibitors (SSRIs), such as fluvoxamine, with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and fluvoxamine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Fosamprenavir: (Moderate) Caution is advised when administering morphine with fosamprenavir, as concurrent use may result in reduced morphine plasma concentrations. Morphine is a substrate for the drug transporter P-glycoprotein (P-gp). Amprenavir, the active metabolite of fosamprenavir, is a P-gp inducer.
    Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Fosphenytoin: (Major) Clinically significant interactions, including withdrawal reactions, may occur with the combined use of opiate agonists and fosphenytoin, which induces CYP450 isoenzymes. Concomitant use of fosphenytoin with opiate agonists may necessitate dose adjustment of the opiate to achieve analgesia or to prevent withdrawal in patients on chronic opiate therapy. In addition, it is possible that additive CNS depression could be seen with the combined use of the hydantoin and opiate agonist.
    Fospropofol: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended. Monitor patients for sedation and respiratory depression.
    Fostamatinib: (Moderate) Monitor for an increase in morphine-related adverse reactions, including hypotension, sedation, and respiratory depression, if coadministration with fostamatinib is necessary; a dose adjustment of morphine may be necessary. Morphine is a P-glycoprotein (P-gp) substrate. Fostamatinib is a P-gp inhibitor and has the potential to increase plasma concentrations of P-gp substrates; however, the clinical relevance of this finding is unknown. Coadministration with P-gp inhibitors can increase morphine exposure by about 2-fold.
    Frovatriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor agonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor agonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Furosemide: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction.
    Gabapentin: (Moderate) Patients who require concomitant treatment with morphine may experience increases in gabapentin serum concentrations. Patients should be carefully observed for signs of CNS depression, such as somnolence, and the dose of gabapentin and/or morphine should be reduced appropriately.
    General anesthetics: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended. Monitor patients for sedation and respiratory depression.
    Glecaprevir; Pibrentasvir: (Moderate) Caution is advised with the coadministration of glecaprevir and morphine as coadministration may increase serum concentrations of morphine and increase the risk of adverse effects. Morphine is a substrate of P-glycoprotein (P-gp); glecaprevir is a P-gp inhibitor. (Moderate) Caution is advised with the coadministration of pibrentasvir and morphine as coadministration may increase serum concentrations of morphine and increase the risk of adverse effects. Morphine is a substrate of P-glycoprotein (P-gp); pibrentasvir is an inhibitor of P-gp.
    Glycopyrrolate: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Glycopyrrolate; Formoterol: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Granisetron: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor antagonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor antagonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Guaifenesin; Hydrocodone: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression.
    Guaifenesin; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression.
    Guanabenz: (Moderate) Guanabenz is associated with sedative effects. Guanabenz can potentiate the effects of CNS depressants such as opiate agonists, when administered concomitantly.
    Guanfacine: (Moderate) Central-acting adrenergic agonists like guanfacine have CNS depressive effects and can potentiate the actions of other CNS depressants including opiate agonists.
    Haloperidol: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include haloperidol. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Halothane: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended. Monitor patients for sedation and respiratory depression.
    Homatropine; Hydrocodone: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hydralazine; Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Irbesartan: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Lisinopril: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Losartan: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Methyldopa: (Moderate) Methyldopa is associated with sedative effects. Methyldopa can potentiate the effects of CNS depressants, such as opiate agonists, when administered concomitantly. (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Metoprolol: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Olmesartan: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Propranolol: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Quinapril: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Spironolactone: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Telmisartan: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Triamterene: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrochlorothiazide, HCTZ; Valsartan: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Hydrocodone: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression.
    Hydrocodone; Ibuprofen: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression.
    Hydrocodone; Phenylephrine: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression.
    Hydrocodone; Potassium Guaiacolsulfonate: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression.
    Hydrocodone; Potassium Guaiacolsulfonate; Pseudoephedrine: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression.
    Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with morphine may lead to hypotension, profound sedation, coma, respiratory depression and death. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Hydrocodone should be used in reduced dosages if used concurrently with a CNS depressant; initiate hydrocodone at 20 to 30% of the usual dosage. Also, consider a using a lower dose of morphine. Monitor patients for sedation and respiratory depression.
    Hydromorphone: (Major) Concomitant use of hydromorphone with morphine can potentiate the effects of both drugs and may lead to additive CNS or respiratory depression, profound sedation, or coma. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of hydromorphone and/or morphine is recommended; start with one-third to one-half of the estimated hydromorphone starting dose when using hydromorphone extended-release tablets. For morphine extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Carefully monitor the patient for hypotension, CNS depression, and respiratory depression.
    Hydroxyzine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Hyoscyamine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Severe) Morphine use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Methylene blue is a reversible inhibitor of MAO. Concomitant use of morphine with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as morphine. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Ibuprofen; Oxycodone: (Major) Concomitant use of oxycodone with morphine may lead to additive respiratory and/or CNS depression. Hypotension, profound sedation, coma, respiratory depression, or death may occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of oxycodone and/or morphine is recommended; use an initial dose of oxycodone at one-third to one-half the usual dosage. For extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor for sedation and respiratory depression.
    Iloperidone: (Moderate) Concomitant use of iloperidone with other centrally-acting medications, such as morphine, may increase both the frequency and the intensity of adverse effects including drowsiness, sedation, and dizziness.
    Imipramine: (Major) Concomitant use of morphine with other CNS depressants, such as tricyclic antidepressants (TCAs), can potentiate the effects of morphine on respiration, blood pressure, and alertness. Use may cause profound sedation, hypotension, hypoventilation, or coma. Orthostasis may occur in ambulatory patients. Additive effects such as constipation may also occur. Prior to concurrent use of morphine in patients taking a TCA, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a TCA is used concurrently with morphine, usually, a reduced initial dosage of morphine is to be considered. For example, for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). A reduced dosage of the TCA may also be necessary. Monitor patients for sedation, hypotension, reduced GI motility, and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering TCAs with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the TCA should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Indacaterol; Glycopyrrolate: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Isocarboxazid: (Severe) Morphine use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Concomitant use of morphine with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as morphine.
    Isoflurane: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended. Monitor patients for sedation and respiratory depression.
    Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Moderate) Rifampin may induce the metabolism of morphine and lead to loss of analgesia if coadministered.
    Isoniazid, INH; Rifampin: (Moderate) Rifampin may induce the metabolism of morphine and lead to loss of analgesia if coadministered.
    Ivacaftor: (Moderate) Use caution when administering ivacaftor and morphine concurrently. Ivacaftor is an inhibitor of P-glycoprotein (P-gp). Coadministration of ivacaftor with P-gp substrates, such as morphine, can increase morphine exposure leading to increased or prolonged therapeutic effects and adverse events.
    Ixabepilone: (Minor) Ixabepilone is a weak inhibitor of P-glycoprotein (P-gp). Morphine is a P-gp substrate, and concomitant use may cause an increase in morphine concentrations. Use caution if ixabepilone is coadministered with morphine and monitor for an increase in side effects.
    Ketamine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended. Monitor patients for sedation and respiratory depression.
    Lactobacillus: (Moderate) Concurrent use of antidiarrheals and opiate agonists, can lead to severe constipation and possibly additive CNS depression. Opioids increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Ledipasvir; Sofosbuvir: (Moderate) Caution and close monitoring of morphine-associated adverse reactions is advised with concomitant administration of ledipasvir. Morphine is a substrate of the drug transporter P-glycoprotein (P-gp); ledipasvir is a P-gp inhibitor. Taking these drugs together may increase morphine plasma concentrations.
    Leuprolide; Norethindrone: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Levobupivacaine: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Levocetirizine: (Moderate) Additive drowsiness may occur if cetirizine or levocetirizine is administered with other drugs that depress the CNS, including opiate agonists.
    Levomilnacipran: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the SNRI should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Levonorgestrel: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Lidocaine: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Lincosamides: (Moderate) Lincosamides, which have been shown to exhibit neuromuscular blocking action, can enhance the effects of opiate agonists if used concomitantly, enhancing respiratory depressant effects. They should be used together with caution and the patient carefully monitored.
    Linezolid: (Severe) Morphine use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Linezolid is a reversible, non-selective inhibitor of MAO. Concomitant use of morphine with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as morphine.
    Lofexidine: (Moderate) Monitor for excessive hypotension and sedation during coadministration of lofexidine and morphine. Lofexidine can potentiate the effects of CNS depressants.
    Loop diuretics: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction.
    Loperamide: (Moderate) Additive constipation may be seen with concurrent use of opiate agonists and antidiarrheals. Opioids increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. Concurrent use of selected antidiarrheals (e.g., loperamide, diphenoxylate) and opiate agonists can lead to additive CNS depression.
    Loperamide; Simethicone: (Moderate) Additive constipation may be seen with concurrent use of opiate agonists and antidiarrheals. Opioids increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. Concurrent use of selected antidiarrheals (e.g., loperamide, diphenoxylate) and opiate agonists can lead to additive CNS depression.
    Lopinavir; Ritonavir: (Moderate) Close clinical monitoring is advised when administering morphine with ritonavir due to an increased potential for morphine-related adverse events, including hypotension, respiratory depression, profound sedation, coma, and death. Dosage reductions of morphine and/or ritonavir may be required. Morphine is a substrate of the drug efflux transporter P-glycoprotein (P-gp); ritonavir is an inhibitor of this efflux protein. Coadministration may cause an approximate 2-fold increase in morphine exposure.
    Lorazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Loxapine: (Moderate) Loxapine can potentiate the actions of other CNS depressants such as opiate agonists. Caution should be exercised with simultaneous use of these agents due to potential excessive CNS effects.
    Lumacaftor; Ivacaftor: (Minor) Although the clinical significance of this interaction is unknown, concurrent use of morphine and lumacaftor; ivacaftor may alter morphine exposure; caution and close monitoring are advised if these drugs are used together. Morphine is a substrate of the drug transporter P-glycoprotein (P-gp). In vitro data suggest that lumacaftor; ivacaftor has the potential to both induce and inhibit P-gp. The net effect of lumacaftor; ivacaftor on P-gp transport is not clear, but substrate exposure may be affected leading to decreased efficacy or increased or prolonged therapeutic effects and adverse events.
    Lumacaftor; Ivacaftor: (Moderate) Use caution when administering ivacaftor and morphine concurrently. Ivacaftor is an inhibitor of P-glycoprotein (P-gp). Coadministration of ivacaftor with P-gp substrates, such as morphine, can increase morphine exposure leading to increased or prolonged therapeutic effects and adverse events.
    Lurasidone: (Moderate) Due to the CNS effects of lurasidone, caution should be used when lurasidone is given in combination with other centrally acting medications such as opiate agonists.
    Magnesium Salts: (Minor) Because of the CNS-depressant effects of magnesium sulfate, additive central-depressant effects can occur following concurrent administration with CNS depressants such as opiate agonists. Caution should be exercised when using these agents concurrently.
    Maprotiline: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include maprotiline. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Meclizine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Memantine: (Moderate) Cationic drugs that are eliminated by renal tubular secretion, such as morphine, may compete with memantine for common renal tubular transport systems, thus possibly decreasing the elimination of one of the drugs. Although theoretical, careful patient monitoring of response to memantine and/or morphine is recommended to assess for needed dosage adjustments.
    Mepenzolate: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Mephobarbital: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Mepivacaine: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Mepivacaine; Levonordefrin: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Meprobamate: (Moderate) Concomitant use of morphine with meprobamate can potentiate the effects of morphine on respiration, blood pressure, and alertness. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If meprobamate is used concurrently with morphine, a reduced dosage of morphine and/or meprobamate is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Mesoridazine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Severe hypotension may occur if morphine is administered to a patient taking phenothiazines. Profound sedation and coma may also occur. Prior to use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules).
    Mestranol; Norethindrone: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Metaxalone: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Methadone: (Major) Concomitant use of morphine with methadone can potentiate the effects of both drugs on respiration, blood pressure, and alertness. Profound sedation and coma may also occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of morphine and/or methadone is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Severe) Morphine use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Methylene blue is a reversible inhibitor of MAO. Concomitant use of morphine with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as morphine. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Methocarbamol: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Methohexital: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Methscopolamine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Methyclothiazide: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Methyldopa: (Moderate) Methyldopa is associated with sedative effects. Methyldopa can potentiate the effects of CNS depressants, such as opiate agonists, when administered concomitantly.
    Methylene Blue: (Severe) Morphine use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Methylene blue is a reversible inhibitor of MAO. Concomitant use of morphine with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as morphine.
    Metoclopramide: (Moderate) Opiate agonists antagonize GI motility and can decrease the gastroprokinetic effects of metoclopramide.
    Metolazone: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Metyrapone: (Moderate) Metyrapone may cause dizziness and/or drowsiness. Other drugs that may also cause drowsiness, such as opiate agonists, should be used with caution. Additive drowsiness and/or dizziness is possible.
    Metyrosine: (Moderate) The concomitant administration of metyrosine with opiate agonists can result in additive sedative effects.
    Midazolam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Milnacipran: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the SNRI should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Minocycline: (Minor) Injectable minocycline contains magnesium sulfate heptahydrate. Because of the CNS-depressant effects of magnesium sulfate, additive central-depressant effects can occur following concurrent administration with CNS depressants such as opiate agonists. Caution should be exercised when using these agents concurrently.
    Mirtazapine: (Major) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include mirtazapine. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs with serotonergic properties such as morphine and mirtazapine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and mirtazapine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Mivacurium: (Moderate) Concomitant use of morphine with other CNS depressants, such as neuromuscular blockers, can potentiate the effects of morphine on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
    Molindone: (Moderate) Concomitant use of opiate agonists with other central nervous system (CNS) depressants, such as molindone, can potentiate the effects of the opiate and may lead to additive CNS or respiratory depression, profound sedation, or coma. Prior to concurrent use of an opiate in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If these agents are used together, a reduced dosage of the opiate and/or molindone is recommended. Carefully monitor the patient for hypotension, CNS depression, and respiratory depression. Carbon dioxide retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids.
    Monoamine oxidase inhibitors: (Severe) Morphine use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Concomitant use of morphine with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as morphine.
    Nabilone: (Moderate) Concomitant use of opiate agonists with other central nervous system (CNS) depressants, such as nabilone, can potentiate the effects of the opiate and may lead to additive CNS or respiratory depression, profound sedation, or coma. Prior to concurrent use of an opiate in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If these agents are used together, a reduced dosage of the opiate and/or the CNS depressant is recommended. Carefully monitor the patient for hypotension, CNS depression, and respiratory depression. Carbon dioxide retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids.
    Nalbuphine: (Major) Avoid the concomitant use of nalbuphine and opiate agonists, such as morphine. Nalbuphine is a mixed opiate agonist/antagonist that may block the effects of opiate agonists and reduce analgesic effects of morphine. Nalbuphine may cause withdrawal symptoms in patients receiving chronic opiate agonists. Concurrent use of nalbuphine with other opiate agonists can cause additive CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist.
    Naloxone: (Major) Naloxone can antagonize the therapeutic efficacy of morphine in addition to precipitating withdrawal symptoms in patients who are physically dependent on opiate drugs including morphine. Naloxone should not be administered in the absence of clinically significant respiratory or circulatory depression secondary to morphine overdose.
    Naltrexone: (Major) When naltrexone is used as adjuvant treatment of opiate or alcohol dependence, use is contraindicated in patients currently receiving opiate agonists. Naltrexone will antagonize the therapeutic benefits of opiate agonists and will induce a withdrawal reaction in patients with physical dependence to opioids. Also, patients should be opiate-free for at least 7 to 10 days prior to initiating naltrexone therapy. If there is any question of opioid use in the past 7 to 10 days and the patient is not experiencing opioid withdrawal symptoms and/or the urine is negative for opioids, a naloxone challenge test needs to be performed. If a patient receives naltrexone, and an opiate agonist is needed for an emergency situation, large doses of opiate agonists may ultimately overwhelm naltrexone antagonism of opiate receptors. Immediately following administration of exogenous opiate agonists, the opiate plasma concentration may be sufficient to overcome naltrexone competitive blockade, but the patient may experience deeper and more prolonged respiratory depression and thus, may be in danger of respiratory arrest and circulatory collapse. Non-receptor mediated actions like facial swelling, itching, generalized erythema, or bronchoconstriction may occur presumably due to histamine release. A rapidly acting opiate agonist is preferred as the duration of respiratory depression will be shorter. Patients receiving naltrexone may also experience opiate side effects with low doses of opiate agonists. If the opiate agonist is taken in such a way that high concentrations remain in the body beyond the time naltrexone exerts its therapeutic effects, serious side effects may occur.
    Naproxen; Sumatriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor agonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor agonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Naratriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor agonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor agonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Nefazodone: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include nefazodone. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Neratinib: (Moderate) Monitor for an increase in morphine-related adverse reactions including hypotension, sedation, and respiratory depression if coadministration with neratinib is necessary. Morphine is a P-glycoprotein (P-gp) substrate. Neratinib may inhibit the transport of P-gp substrates. Concomitant use of P-gp inhibitors can increase morphine exposure by approximately 2-fold.
    Nesiritide, BNP: (Major) The potential for hypotension may be increased when coadministering nesiritide with opiate agonists.
    Neuromuscular blockers: (Moderate) Concomitant use of morphine with other CNS depressants, such as neuromuscular blockers, can potentiate the effects of morphine on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
    Nitroglycerin: (Minor) Nitroglycerin can cause hypotension. This action may be additive with other agents that can cause hypotension such as opiate agonists. Patients should be monitored more closely for hypotension if nitroglycerin is used concurrently with opiate agonists.
    Norethindrone: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Norgestrel: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Nortriptyline: (Major) Concomitant use of morphine with other CNS depressants, such as tricyclic antidepressants (TCAs), can potentiate the effects of morphine on respiration, blood pressure, and alertness. Use may cause profound sedation, hypotension, hypoventilation, or coma. Orthostasis may occur in ambulatory patients. Additive effects such as constipation may also occur. Prior to concurrent use of morphine in patients taking a TCA, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a TCA is used concurrently with morphine, usually, a reduced initial dosage of morphine is to be considered. For example, for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). A reduced dosage of the TCA may also be necessary. Monitor patients for sedation, hypotension, reduced GI motility, and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering TCAs with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the TCA should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Octreotide: (Moderate) Octreotide can cause additive constipation with opiate agonists such as morphine. Opioids increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. Octreotide may also decrease the analgesic effect of morphine. If a loss or decrease in pain control occurs with concomitant therapy, consider discontinuing the octreotide.
    Olanzapine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include olanzapine. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Ombitasvir; Paritaprevir; Ritonavir: (Moderate) Close clinical monitoring is advised when administering morphine with ritonavir due to an increased potential for morphine-related adverse events, including hypotension, respiratory depression, profound sedation, coma, and death. Dosage reductions of morphine and/or ritonavir may be required. Morphine is a substrate of the drug efflux transporter P-glycoprotein (P-gp); ritonavir is an inhibitor of this efflux protein. Coadministration may cause an approximate 2-fold increase in morphine exposure.
    Ondansetron: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor antagonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor antagonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Oral Contraceptives: (Moderate) Combination oral contraceptives have been shown to decrease plasma concentrations of morphine, due to induction of conjugation. Monitor for decreased efficacy of morphine.
    Orphenadrine: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Osimertinib: (Moderate) Monitor for an increase in morphine-related adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death, if coadministration with osimertinib is necessary; decrease the dose of morphine as clinically appropriate. Morphine is a P-glycoprotein (P-gp) substrate and osimertinib is a P-gp inhibitor. The concomitant use of P-gp inhibitors can increase the exposure to morphine by about 2-fold.
    Oxazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Oxybutynin: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Oxycodone: (Major) Concomitant use of oxycodone with morphine may lead to additive respiratory and/or CNS depression. Hypotension, profound sedation, coma, respiratory depression, or death may occur. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. A reduced dosage of oxycodone and/or morphine is recommended; use an initial dose of oxycodone at one-third to one-half the usual dosage. For extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor for sedation and respiratory depression.
    Oxymorphone: (Major) Concomitant use of oxymorphone with morphine may produce additive CNS depressant effects. Respiratory depression, hypotension, profound sedation, or coma may result from combination therapy. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Oxymorphone should be used in reduced dosages if used concurrently with a CNS depressant; initiate oxymorphone at one-third to one-half the usual dosage in patients that are also receiving morphine. A reduced dosage of morphine may also be necessary. If the patient is receiving an extended-release product, start with the lowest possible dose of morphine. Slowly titrate the dose as necessary for adequate pain relief and monitor for sedation or respiratory depression.
    Paliperidone: (Moderate) Drugs that can cause CNS depression such as opiate agonists, if used concomitantly with paliperidone, can increase both the frequency and the intensity of adverse effects such as drowsiness, sedation, and dizziness.
    Palonosetron: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor antagonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor antagonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Pancuronium: (Moderate) Concomitant use of morphine with other CNS depressants, such as neuromuscular blockers, can potentiate the effects of morphine on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
    Papaverine: (Moderate) Papaverine is a benzylisoquinoline alkaloid of opium and may have synergistic effects with opiate agonists. Concurrent use of papaverine with potent CNS depressants could lead to enhanced sedation.
    Paroxetine: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering selective serotonin reuptake inhibitors (SSRIs), such as paroxetine, with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and paroxetine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Pegvisomant: (Moderate) In clinical trials, patients taking opiate agonists often required higher serum pegvisomant concentrations to achieve appropriate IGF-I suppression compared with patients not receiving opiate agonists. The mechanism of this interaction is unknown.
    Pentazocine: (Major) Avoid the concomitant use of pentazocine and opiate agonists, such as morphine. Pentazocine is a mixed opiate agonist/antagonist that may block the effects of opiate agonists and reduce analgesic effects of morphine. Pentazocine may cause withdrawal symptoms in patients receiving chronic opiate agonists. Concurrent use of pentazocine with other opiate agonists can cause additive CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist.
    Pentazocine; Naloxone: (Major) Avoid the concomitant use of pentazocine and opiate agonists, such as morphine. Pentazocine is a mixed opiate agonist/antagonist that may block the effects of opiate agonists and reduce analgesic effects of morphine. Pentazocine may cause withdrawal symptoms in patients receiving chronic opiate agonists. Concurrent use of pentazocine with other opiate agonists can cause additive CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist. (Major) Naloxone can antagonize the therapeutic efficacy of morphine in addition to precipitating withdrawal symptoms in patients who are physically dependent on opiate drugs including morphine. Naloxone should not be administered in the absence of clinically significant respiratory or circulatory depression secondary to morphine overdose.
    Pentobarbital: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Perampanel: (Moderate) Co-administration of perampanel with CNS depressants, including ethanol, may increase CNS depression. The combination of perampanel (particularly at high doses) with ethanol has led to decreased mental alertness and ability to perform complex tasks (such as driving), as well as increased levels of anger, confusion, and depression; similar reactions should be expected with concomitant use of other CNS depressants, such as opiate agonists.
    Perphenazine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Severe hypotension may occur if morphine is administered to a patient taking phenothiazines. Profound sedation and coma may also occur. Prior to use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules).
    Perphenazine; Amitriptyline: (Major) Concomitant use of morphine with other CNS depressants, such as tricyclic antidepressants (TCAs), can potentiate the effects of morphine on respiration, blood pressure, and alertness. Use may cause profound sedation, hypotension, hypoventilation, or coma. Orthostasis may occur in ambulatory patients. Additive effects such as constipation may also occur. Prior to concurrent use of morphine in patients taking a TCA, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a TCA is used concurrently with morphine, usually, a reduced initial dosage of morphine is to be considered. For example, for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). A reduced dosage of the TCA may also be necessary. Monitor patients for sedation, hypotension, reduced GI motility, and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering TCAs with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the TCA should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated. (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Severe hypotension may occur if morphine is administered to a patient taking phenothiazines. Profound sedation and coma may also occur. Prior to use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules).
    Phenelzine: (Severe) Morphine use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Concomitant use of morphine with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as morphine.
    Phenobarbital: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Phenothiazines: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Severe hypotension may occur if morphine is administered to a patient taking phenothiazines. Profound sedation and coma may also occur. Prior to use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules).
    Phenytoin: (Major) Clinically significant interactions, including withdrawal reactions, may occur with the combined use of opiate agonists and phenytoin, which induces CYP450 isoenzymes. Concomitant use of phenytoin with opiate agonists may necessitate dose adjustment of the opiate to achieve analgesia or to prevent withdrawal in patients on chronic opiate therapy. In addition, it is possible that additive CNS depression could be seen with the combined use of morphine and phenytoin.
    Pimozide: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include pimozide. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Posaconazole: (Moderate) Posaconazole and morphine should be coadministered with caution due to a potential for altered plasma concentrations of both drugs. Both morphine and posaconazole are substrates of the drug efflux protein, P-glycoprotein, which when administered together may increase the absorption or decrease the clearance of the other drug. This interaction may cause alterations in the plasma concentrations of both posaconazole and morphine, ultimately resulting in an increased risk of adverse events.
    Potassium-sparing diuretics: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction.
    Pramipexole: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include pramipexole. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Pramlintide: (Major) Pramlintide slows gastric emptying and the rate of nutrient delivery to the small intestine. Medications with the potential to slow GI motility, such as opiate agonists, should be used with caution, if at all, with pramlintide until more data are available from the manufacturer. Monitor blood glucose.
    Prasugrel: (Moderate) Consider the use of a parenteral anti-platelet agent for patients with acute coronary syndrome who require concomitant opioid agonists. Coadministration of opioid agonists with prasugrel delays and reduces the absorption of prasugrel's active metabolite due to slowed gastric emptying.
    Pregabalin: (Moderate) Concomitant use of opiate agonists with other central nervous system (CNS) depressants can potentiate the effects of the opiate and may lead to additive CNS or respiratory depression, profound sedation, or coma. Examples of drugs associated with CNS depression include pregabalin. Prior to concurrent use of an opiate in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If these agents are used together, a reduced dosage of the opiate and/or the CNS depressant is recommended. Carefully monitor the patient for hypotension, CNS depression, and respiratory depression. Carbon dioxide retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids.
    Prilocaine: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Prilocaine; Epinephrine: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Primidone: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Procaine: (Minor) Due to the central nervous system depression potential of local anesthetics, they should be used with caution with other agents that can cause respiratory depression, such as opiate agonists.
    Procarbazine: (Moderate) In theory, monoamine oxidase inhibitors (MAOIs) potentiate the CNS depression and hypotension caused by opiate agonists such as morphine. Procarbazine is a weak inhibitor of MAO; the manufacturers of morphine do not recommend its use within 14 days of an MAO Inhibitor. Caution is advised until more data are available.
    Prochlorperazine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Severe hypotension may occur if morphine is administered to a patient taking phenothiazines. Profound sedation and coma may also occur. Prior to use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules).
    Propantheline: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Propofol: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended. Monitor patients for sedation and respiratory depression.
    Protriptyline: (Major) Concomitant use of morphine with other CNS depressants, such as tricyclic antidepressants (TCAs), can potentiate the effects of morphine on respiration, blood pressure, and alertness. Use may cause profound sedation, hypotension, hypoventilation, or coma. Orthostasis may occur in ambulatory patients. Additive effects such as constipation may also occur. Prior to concurrent use of morphine in patients taking a TCA, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a TCA is used concurrently with morphine, usually, a reduced initial dosage of morphine is to be considered. For example, for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). A reduced dosage of the TCA may also be necessary. Monitor patients for sedation, hypotension, reduced GI motility, and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering TCAs with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the TCA should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Quazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Quetiapine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include quetiapine. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Quinidine: (Moderate) Morphine is a substrate for P-glycoprotein (P-gp), and quinidine is a P-gp substrate and inhibitor. Coadministration may lead to increased systemic exposure of morphine and morphine-related side effects.
    Rapacuronium: (Moderate) Concomitant use of morphine with other CNS depressants, such as neuromuscular blockers, can potentiate the effects of morphine on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
    Rasagiline: (Severe) Rasagiline is contraindicated for use with morphine due to the risk of serotonin syndrome. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. At least 14 days should elapse between the discontinuation of rasagiline and the initiation of morphine.
    Rifampin: (Moderate) Rifampin may induce the metabolism of morphine and lead to loss of analgesia if coadministered.
    Risperidone: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include risperidone. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Ritonavir: (Moderate) Close clinical monitoring is advised when administering morphine with ritonavir due to an increased potential for morphine-related adverse events, including hypotension, respiratory depression, profound sedation, coma, and death. Dosage reductions of morphine and/or ritonavir may be required. Morphine is a substrate of the drug efflux transporter P-glycoprotein (P-gp); ritonavir is an inhibitor of this efflux protein. Coadministration may cause an approximate 2-fold increase in morphine exposure.
    Rizatriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor agonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor agonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Rocuronium: (Moderate) Concomitant use of morphine with other CNS depressants, such as neuromuscular blockers, can potentiate the effects of morphine on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
    Rolapitant: (Major) Use caution if morphine and rolapitant are used concurrently, and monitor for morphine-related adverse effects. Morphine is a P-glycoprotein (P-gp) substrate, where an increase in exposure may significantly increase adverse effects; rolapitant is a P-gp inhibitor. When rolapitant was administered with another P-gp substrate, digoxin, the day 1 Cmax and AUC were increased by 70% and 30%, respectively; the Cmax and AUC on day 8 were not studied.
    Ropinirole: (Moderate) Concomitant use of opiate agonists with other central nervous system (CNS) depressants such as ropinirole can potentiate the effects of the opiate and may lead to additive CNS or respiratory depression, profound sedation, or coma. Prior to concurrent use of an opiate in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If these agents are used together, a reduced dosage of the opiate and/or the CNS depressant is recommended. Carefully monitor the patient for hypotension, CNS depression, and respiratory depression. Carbon dioxide retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids.
    Ropivacaine: (Moderate) The use of these drugs together must be approached with caution. Although commonly used together for additive analgesic effects, the patient must be monitored for respiratory depression, hypotension, and excessive sedation due to additive effects on the CNS and blood pressure. In rare instances, serious morbidity and mortality has occurred. Limit the use of opiate pain medications with local anesthetics to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. The use of the local anesthetic will allow for the use a lower initial dose of the opiate and then the doses can be titrated to proper clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Safinamide: (Severe) Safinamide is contraindicated for use with morphine due to the risk of serotonin syndrome. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. At least 14 days should elapse between the discontinuation of safinamide and the initiation of morphine.
    Sapropterin: (Moderate) Caution is advised with the concomitant use of sapropterin and morphine as coadministration may result in increased systemic exposure of morphine. Morphine is a substrate for the drug transporter P-glycoprotein (P-gp); in vitro data show that sapropterin may inhibit P-gp. If these drugs are used together, closely monitor for increased side effects of morphine.
    Scopolamine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Secobarbital: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Sedating H1-blockers: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Selegiline: (Severe) Morphine use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Concomitant use of morphine with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as morphine.
    Serotonin norepinephrine reuptake inhibitors: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the SNRI should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Serotonin-Receptor Agonists: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor agonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor agonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Serotonin-Receptor Antagonists: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor antagonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor antagonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Sertraline: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering selective serotonin reuptake inhibitors (SSRIs), such as sertraline, with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and sertraline should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Sevoflurane: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended. Monitor patients for sedation and respiratory depression.
    Sildenafil: (Moderate) Prolonged erections have been reported in two patients taking sildenafil with dihydrocodeine. Although more data are needed, use caution when prescribing opiate agonists and sildenafil concomitantly.
    Simeprevir: (Moderate) Concomitant use of simeprevir and morphine may result in increased morphine plasma concentrations and side effects. Morphine is metabolized by P-glycoprotein (P-gp) and simeprevir inhibits P-gp. Monitor patients for adverse events such as CNS and respiratory depression.
    Sincalide: (Moderate) As morphine may cause constriction of the sphincter of Oddi, a direct counteraction to sincalide, concomitant therapy is usually not advisable. However, morphine augmentation may be desirable in place of delayed imaging in cases when acute cholecystitis is suspected. Withhold opioids for 4 hours prior to radiographic study of the hepatobiliary system with sincalide.
    Skeletal Muscle Relaxants: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Sodium Oxybate: (Major) Additive CNS depressant effects may be possible when sodium oxybate is used concurrently with opiate agonists.
    Sofosbuvir; Velpatasvir; Voxilaprevir: (Moderate) Plasma concentrations of morphine, a P-glycoprotein (P-gp) substrate, may be increased when administered concurrently with voxilaprevir, a P-gp inhibitor. Monitor patients for increased side effects if these drugs are administered concurrently.
    Solifenacin: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug, such as solifenacin. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Sorafenib: (Moderate) Sorafenib inhibits glucuronidation by the UGT1A1 and UGT1A9 pathways. Although specific drug interaction studies have not been completed, systemic exposure to substrates of UGT1A1, like morphine, and UGT1A9 may increase when coadministered with sorafenib.
    Spironolactone: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction.
    St. John's Wort, Hypericum perforatum: (Major) Some data indicate that St. John's wort, Hypericum perforatum may increase the expression of P-glycoprotein (P-gp), resulting in increased efflux and lowered serum concentrations of interacting medications that are substrates for P-gp, such as morphine. Therefore, concurrent use of St. John's wort and morphine may necessitate increased doses of morphine to achieve analgesia and prevent withdrawal. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and St. John's wort. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and St. John's wort should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Succinylcholine: (Moderate) Concomitant use of morphine with other CNS depressants, such as neuromuscular blockers, can potentiate the effects of morphine on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
    Sufentanil: (Moderate) Concomitant use of sufentanil with morphine can potentiate sufentanil-induced CNS and cardiovascular effects and the duration of these effects. A dose reduction of one or both drugs may be warranted.
    Sumatriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor agonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor agonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Suvorexant: (Major) Concomitant use of opioid agonists with suvorexant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with suvorexant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opioid agonist is initiated in a patient taking suvorexant, reduce initial dosage and titrate to clinical response. If suvorexant is prescribed in a patient taking an opioid agonist, use a lower initial dose of suvorexant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Tapentadol: (Major) Additive CNS depressive effects are expected if tapentadol is used in conjunction with other CNS depressants, including other opiate agonists. Severe hypotension, profound sedation, coma, or respiratory depression may occur. Prior to concurrent use of tapentadol in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If an opiate agonist is used concurrently with tapentadol, a reduced dosage of tapentadol and/or the opiate agonist is recommended. If the extended-release tapentadol tablets are used concurrently with a CNS depressant, it is recommended to use an initial tapentadol dose of 50 mg PO every 12 hours. Monitor patients for sedation and respiratory depression.
    Telaprevir: (Moderate) Close clinical monitoring is advised when administering morphine with telaprevir due to an increased potential for morphine-related adverse events. If morphine dose adjustments are made, re-adjust the dose upon completion of telaprevir treatment. Although this interaction has not been studied, predictions about the interaction can be made based on the metabolic pathway of morphine. Morphine is a substrate of the drug efflux transporter P-glycoprotein (P-gp); telaprevir is an inhibitor of this efflux protein. Coadministration may result in elevated morphine plasma concentrations.
    Temazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Temsirolimus: (Moderate) Monitor for an increase in morphine-related adverse reactions, including sedation and respiratory depression, if coadministration with temsirolimus is necessary; a morphine dose adjustment may be necessary. Morphine is a P-glycoprotein (P-gp) substrate and temsirolimus is a P-gp inhibitor. Coadministration with P-gp inhibitors can increase morphine exposure by about 2-fold.
    Tetrabenazine: (Major) Additive effects are possible when tetrabenazine is combined with other drugs that cause CNS depression. Concurrent use of tetrabenazine and drugs that can cause CNS depression, such as opiate agonists, can increase both the frequency and the intensity of adverse effects such as drowsiness, sedation, dizziness, and orthostatic hypotension.
    Tetracaine: (Minor) Due to the central nervous system depression potential of local anesthetics, they should be used with caution with other agents that can cause respiratory depression, such as opiate agonists.
    Tezacaftor; Ivacaftor: (Moderate) Use caution when administering ivacaftor and morphine concurrently. Ivacaftor is an inhibitor of P-glycoprotein (P-gp). Coadministration of ivacaftor with P-gp substrates, such as morphine, can increase morphine exposure leading to increased or prolonged therapeutic effects and adverse events.
    Thalidomide: (Major) Avoid the concomitant use of thalidomide with opiate agonists; antihistamines; antipsychotics; anxiolytics, sedatives, and hypnotics; and other central nervous system depressants due to the potential for additive sedative effects.
    Thiazide diuretics: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Thiethylperazine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Severe hypotension may occur if morphine is administered to a patient taking phenothiazines. Profound sedation and coma may also occur. Prior to use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules).
    Thiopental: (Major) Concomitant use of opioid agonists with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a barbiturate, reduced initial dosages are recommended. For extended-release tablets, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours). Use an initial morphine; naltrexone dose that is 1/3 to 1/2 the recommended starting dose. If a barbiturate is prescribed for a patient taking an opiate agonist, use a lower initial dose of the barbiturate and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Thioridazine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Severe hypotension may occur if morphine is administered to a patient taking phenothiazines. Profound sedation and coma may also occur. Prior to use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules).
    Thiothixene: (Moderate) Concomitant use of opiate agonists with other central nervous system (CNS) depressants can potentiate the effects of the opiate and may lead to additive CNS or respiratory depression, profound sedation, or coma. Examples of drugs associated with CNS depression include thiothixene. Prior to concurrent use of an opiate in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If these agents are used together, a reduced dosage of the opiate and/or the CNS depressant is recommended. Carefully monitor the patient for hypotension, CNS depression, and respiratory depression. Carbon dioxide retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids.
    Ticagrelor: (Major) Consider the use of a parenteral anti-platelet agent for patients with acute coronary syndrome who require concomitant morphine. Coadministration of opioid agonists with ticagrelor delays and reduces the absorption of ticagrelor and its active metabolite due to slowed gastric emptying.
    Tizanidine: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a skeletal muscle relaxant, reduced initial dosages are recommended. For extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Tolcapone: (Moderate) Concomitant use of opiate agonists with other central nervous system (CNS) depressants such as COMT inhibitors can potentiate the effects of the opiate and may lead to additive CNS or respiratory depression, profound sedation, or coma. Prior to concurrent use of an opiate in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If these agents are used together, a reduced dosage of the opiate and/or the CNS depressant is recommended. Carefully monitor the patient for hypotension, CNS depression, and respiratory depression. Carbon dioxide retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids.
    Tolterodine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug, such as tolterodine. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Torsemide: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction.
    Tramadol: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and tramadol. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and tramadol should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated. Lastly, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Tranylcypromine: (Severe) Morphine use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Concomitant use of morphine with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as morphine.
    Trazodone: (Major) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include trazodone. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs with serotonergic properties such as morphine and trazodone. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and trazodone should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Triamterene: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction.
    Triazolam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If morphine is initiated in a patient taking a benzodiazepine, reduce initial dosages and titrate to clinical response. For extended-release tablets, start with morphine 15 mg PO every 12 hours, and for extended-release capsules, start with 30 mg PO every 24 hours or less. Use an initial morphine; naltrexone dose of 20 mg/0.8 mg PO every 24 hours. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Tricyclic antidepressants: (Major) Concomitant use of morphine with other CNS depressants, such as tricyclic antidepressants (TCAs), can potentiate the effects of morphine on respiration, blood pressure, and alertness. Use may cause profound sedation, hypotension, hypoventilation, or coma. Orthostasis may occur in ambulatory patients. Additive effects such as constipation may also occur. Prior to concurrent use of morphine in patients taking a TCA, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a TCA is used concurrently with morphine, usually, a reduced initial dosage of morphine is to be considered. For example, for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). A reduced dosage of the TCA may also be necessary. Monitor patients for sedation, hypotension, reduced GI motility, and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering TCAs with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the TCA should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Trifluoperazine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness. Severe hypotension may occur if morphine is administered to a patient taking phenothiazines. Profound sedation and coma may also occur. Prior to use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules).
    Trihexyphenidyl: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Trimethobenzamide: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
    Trimipramine: (Major) Concomitant use of morphine with other CNS depressants, such as tricyclic antidepressants (TCAs), can potentiate the effects of morphine on respiration, blood pressure, and alertness. Use may cause profound sedation, hypotension, hypoventilation, or coma. Orthostasis may occur in ambulatory patients. Additive effects such as constipation may also occur. Prior to concurrent use of morphine in patients taking a TCA, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a TCA is used concurrently with morphine, usually, a reduced initial dosage of morphine is to be considered. For example, for extended-release morphine products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). A reduced dosage of the TCA may also be necessary. Monitor patients for sedation, hypotension, reduced GI motility, and respiratory depression. In addition, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when administering TCAs with other drugs that have serotonergic properties such as morphine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the TCA should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Triprolidine: (Moderate) Concomitant use of morphine with other CNS depressants can potentiate the effects of morphine on respiration, blood pressure, and alertness; examples of other CNS depressants include sedating H1-blockers. Prior to concurrent use of morphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with morphine, a reduced dosage of morphine and/or the CNS depressant is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours, extended-release capsules). Monitor patients for sedation and respiratory depression.
    Trospium: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when trospium, an anticholinergic drug for overactive bladder. is used with opiate agonists. The concomitant use of these drugs together may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. Both agents may also cause drowsiness or blurred vision, and patients should use care in driving or performing other hazardous tasks until the effects of the drugs are known.
    Tubocurarine: (Moderate) Concomitant use of morphine with other CNS depressants, such as neuromuscular blockers, can potentiate the effects of morphine on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
    Valerian, Valeriana officinalis: (Moderate) Any substances that act on the CNS may theoretically interact with valerian, Valeriana officinalis. The valerian derivative, dihydrovaltrate, binds at barbiturate binding sites; valerenic acid has been shown to inhibit enzyme-induced breakdown of GABA in the brain; the non-volatile monoterpenes (valepotriates) have sedative activity. The sedative effect may be additive to other drugs with sedative actions, such as the opiate agonists. Consider the patient's use of alcohol or illicit drugs. If valerian is used concurrently with a CNS depressant, a reduced dosage of the CNS depressant may be required, or, the valerian supplement may be discontinued. Carefully monitor the patient for hypotension, CNS depression, and respiratory depression.
    Vecuronium: (Moderate) Concomitant use of morphine with other CNS depressants, such as neuromuscular blockers, can potentiate the effects of morphine on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
    Vemurafenib: (Moderate) Concomitant use of vemurafenib and morphine may result in increased morphine concentrations. Vemurafenib is a P-glycoprotein (P-gp) inhibitor and morphine is a P-gp substrate. Monitor patients for increased side effects, including CNS or respiratory depression.
    Venlafaxine: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the SNRI should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Vigabatrin: (Moderate) Vigabatrin may cause somnolence and fatigue. Drugs that can cause CNS depression, if used concomitantly with vigabatrin, may increase both the frequency and the intensity of adverse effects such as drowsiness, sedation, and dizziness. Caution should be used when vigabatrin is given with opiate agonists.
    Vilazodone: (Moderate) Due to the CNS effects of vilazodone, caution should be used when vilazodone is given in combination with other centrally acting medications such as opiate agonists.
    Zaleplon: (Moderate) Concomitant use of morphine with zaleplon can potentiate the effects of morphine on respiration, blood pressure, and alertness. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If zaleplon is used concurrently with morphine, a reduced dosage of morphine and/or the zaleplon is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). Monitor patients for sedation and respiratory depression.
    Ziconotide: (Moderate) Concurrent use of ziconotide and opiate agonists may result in an increased incidence of dizziness and confusion. Ziconotide neither interacts with opiate receptors nor potentiates opiate-induced respiratory depression. However, in animal models, ziconotide did potentiate gastrointestinal motility reduction by opioid agonists.
    Ziprasidone: (Moderate) Ziprasidone has the potential to impair cognitive and motor skills. Additive CNS depressant effects are possible when ziprasidone is used concurrently with any CNS depressant, including morphine.
    Zolmitriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin-receptor agonists. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the serotonin-receptor agonist should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Zolpidem: (Moderate) Concomitant use of morphine with zolpidem can potentiate the effects of morphine on respiration, blood pressure, and alertness. In addition, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of zolpidem and other CNS depressants than with zolpidem alone. Prior to concurrent use, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If zolpidem is used concurrently with morphine, a reduced dosage of morphine and/or zolpidem is recommended; for extended-release products, start with the lowest possible dose of morphine (i.e., 15 mg PO every 12 hours, extended-release tablets; 30 mg or less PO every 24 hours; extended-release capsules). For Intermezzo brand of sublingual zolpidem tablets, reduce the dose to 1.75 mg/night. Monitor patients for sedation and respiratory depression.
    Zonisamide: (Minor) Zonisamide is a weak inhibitor of P-glycoprotein (P-gp), and morphine is a substrate of P-gp. There is theoretical potential for zonisamide to affect the pharmacokinetics of drugs that are P-gp substrates. Use caution when starting or stopping zonisamide or changing the zonisamide dosage in patients also receiving drugs which are P-gp substrates.

    PREGNANCY AND LACTATION

    Pregnancy

    Morphine; naltrexone is classified as FDA pregnancy category C. There have been no adequate and well-controlled studies of morphine; naltrexone in pregnant women; however, retrospective and animal data for morphine are available. Morphine readily crosses the placenta. In animal studies, maternally toxic parenteral doses of morphine administered in the second trimester resulted in teratogenic damage in neurological, soft tissue, and skeletal systems. Third trimester exposure in rats and hamsters is associated with reversibly decreased brain, spinal cord, genital, and total body weights in offspring, as well as, delayed growth and maturation, and decreased fertility in both male and female offspring. Morphine; naltrexone is an extended release formulation of morphine not intended for short-term or as-needed dosing and is not indicated for use during labor or obstetric delivery. Further, prolonged maternal use of long-acting opioids, such as morphine; naltrexone, during pregnancy may result in neonatal opioid withdrawal syndrome (NOWS). This syndrome can be life-threatening. Severe symptoms may require pharmacologic therapy managed by clinicians familiar with neonatal opioid withdrawal. Monitor the neonate for withdrawal symptoms including irritability, hyperactivity, abnormal sleep pattern, high-pitched crying, tremor, vomiting, diarrhea, and failure to gain weight. Onset, duration, and severity of opioid withdrawal may vary based on the specific opioid used, duration of use, timing and amount of last maternal use, and rate of elimination by the newborn. Neonates whose mothers have been taking morphine chronically are frequently born small for gestational age, have decreased respiratory drive, and are at an increased risk of sudden infant death syndrome (SIDS). These newborns may show some respiratory depression and/or withdrawal symptoms at birth or within a few days. The risk of respiratory and CNS depression is especially important for premature infants, who are particularly sensitive.

    MECHANISM OF ACTION

    NOTE: This monograph discusses a combination product of morphine and naltrexone. When morphine; naltrexone is administered as intended, the naltrexone component produces no clinically significant effect; however, after tampering (crushing or dissolving), a therapeutic dose of naltrexone is available. Naltrexone-induced opioid antagonism may occur possibly resulting in symptoms of withdrawal. In addition, potentially fatal opiate toxicity is possible if this drug combination is chewed, crushed, or dissolved prior to administration.
     
    •morphine: Morphine is a potent mu-opiate receptor agonist. At higher doses it can interact with other opioid receptors. As with other opioids, the analgesic activity of morphine is central; the drug binds and activates receptors in the brain and spinal cord. There is no ceiling effect of analgesia for opiates. The emotional response to pain is also altered. Opioids close N-type voltage-operated calcium channels (kappa-receptor agonist) and open calcium-dependent inwardly rectifying potassium channels (mu and delta receptor agonist) resulting in hyperpolarization and reduced neuronal excitability. Binding of the opiate stimulates the exchange of guanosine triphosphate (GTP) for guanosine diphosphate (GDP) on the G-protein complex. Binding of GTP leads to a release of the G-protein subunit, which acts on the effector system. In this case of opioid-induced analgesia, the effector system is adenylate cyclase and cAMP located at the inner surface of the plasma membrane. Thus, opioids decrease intracellular cAMP by inhibiting adenylate cyclase that modulates the release of nociceptive neurotransmitters such as substance P, GABA, dopamine, acetylcholine and norepinephrine.
     
    Clinically, stimulation of mu-receptors produces analgesia, euphoria, respiratory depression, miosis, decreased gastrointestinal motility, and physical dependence. Kappa-receptor stimulation also produces analgesia, miosis, respiratory depression, as well as, dysphoria and some psychomimetic effects (i.e., disorientation and/or depersonalization). Miosis is produced by an excitatory action on the autonomic segment of the nucleus of the oculomotor nerve. Respiratory depression is caused by direct action of opiate agonists on respiratory centers in the brain stem. Opiate agonists increase smooth muscle tone in the antral portion of the stomach, the small intestine (especially the duodenum), the large intestine, and the sphincters. Opiate agonists also decrease secretions from the stomach, pancreas, and biliary tract. The combination of effects of opiate agonists on the GI tract results in constipation and delayed digestion. Urinary smooth muscle tone is also increased by opiate agonists. The tone of the bladder detrusor muscle, ureters, and vesical sphincter is increased, which sometimes causes urinary retention. Opioids also modulate the endocrine and immune systems. Opioids inhibit the release of vasopressin, somatostatin, insulin, and glucagon.
     
    •naltrexone: Naltrexone is a competitive antagonist at opiate receptors mu, kappa, and delta; in this combination product, it is added to morphine to deter abuse and/or misuse. When this combination is administered intact, any effect of naltrexone is minimal due to very low absorption of the sequestered nalotrexone. If the capsule or pellets are chewed, crushed, or dissolved in alcohol, naltrexone may be released and thus active. Active naltrexone results in a competitive blockade of opiate receptors. An elimination of the euphoric effect of opiates and withdrawal in opioid tolerant is possible.

    PHARMACOKINETICS

    Morphine; naltrexone is administered orally. This formulation contains an extended-release morphine enclosing an inner core of naltrexone. The sequestered naltrexone is intended to pass through the body without clinically meaningful release or accumulation.
     
    The drug is widely distributed to skeletal muscle, kidneys, liver, intestinal tract, lungs, spleen, and brain with 30—35% plasma protein binding. Morphine is known to cross the placenta in pregnant women and has been found in human breast milk. Metabolism of morphine occurs primarily through conjugation in the liver with glucuronic acid through UDP-glucuronosyltransferases to form 3-glucuronide (50%), 6-glucuronide (5—15%), and 3,6-glucuronide and other minor metabolites. Morphine is also metabolized by P-glycoprotein and cytochrome P450 3A4 enzymes. Morphine 3-glucuronide has a low affinity for opioid receptors, has no analgesic activity, may cause hyperalgesia (hyperesthesia), myoclonus, and allodynia, and may be important in the development of tolerance to morphine. In contrast, morphine 6-glucuronide has analgesic activity and may significantly contribute to morphine's activity. With chronic dosing of morphine, the systemic exposure of the glucuronide metabolites is greater than that of morphine. Excretion of morphine is largely in the urine and bile as the morphine- 3-glucuronide and 6-glucuronide metabolites. Smaller amounts are excreted as secondary conjugates and approximately 10% is eliminated as unchanged drug. Renal clearance of morphine and morphine- 6-glucuronide exceeds creatinine clearance, which suggests that both are actively secreted by the kidney. Between 7—10% is excreted in the feces mainly via the bile. The terminal elimination half-life of morphine after the administration of a single dose of morphine; naltrexone is approximately 29 hours. 

    Oral Route

    Administration with food does not affect the total bioavailability of morphine or compromise the sequestering of naltrexone. Intentional or unintentional misuse by crushing, chewing, or dissolving is expected to result in the rapid release of morphine and naltrexone.
     
    Morphine: Morphine is well absorbed from the gut. As a result of significant first-pass metabolism, bioavailability is approximately 20—40%. The median time to peak morphine plasma concentration is within 60 minutes after immediate-release oral morphine administration and approximately 7.5 hours after Embeda administration.
    Naltrexone: Although the full opiate antagonist effect of naltrexone in this formulation only occurs if the capsule pellets are dissolved or crushed, some naltrexone absorption is possible. In clinical trials, 13 of 67 patients titrated to 120—160 mg/day of morphine; naltrexone (equating to 4.8—6.4 mg of sequestered naltrexone daily) had detectable naltrexone plasma concentrations at steady state. These plasma concentrations ranged from 4—25.5 pg/ml and were significantly lower than the mean plasma level concentration following a single 2.4 mg dose of naltrexone oral solution which is 689 pg/ml. (See naltrexone monograph for more information.)