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  • CLASSES

    Neuropathic Pain and Peripheral Neuropathy Agents
    Serotonin Norepinephrine Reuptake Inhibitor Antidepressants, SNRIs

    BOXED WARNING

    Children, growth inhibition, suicidal ideation

    Duloxetine is not recommended for use in children less than 7 years of age; safety and efficacy have not been established. Duloxetine is FDA-approved for use in children and adolescents 7 years and older with generalized anxiety disorder (GAD); efficacy for major depressive disorder was not established in two 10-week controlled trials with 800 pediatric patients (7 years and older). In October 2004, the FDA directed manufacturers of all antidepressants to include a boxed warning detailing the risk of suicide in pediatric patients. A causal role has been established for antidepressants in inducing suicidally in pediatric patients. The risk of suicidally for these drugs was identified in a pooled analysis of 24 placebo-controlled trials (n = 4400) lasting up to 16 weeks in pediatric patients with major depressive disorder (MDD), obsessive compulsive disorder (OCD), or other psychiatric disorders. The analysis showed a greater risk of suicidally during the first few months of treatment in those receiving antidepressants (SSRIs and others). The average risk of such events on drug was 4% and 2% for placebo; however, no suicides occurred in these trials. Pooled analysis of short-term clinical trials during early phase treatment with SSRIs and other antidepressants in young adults (18 to 24 years) also showed an increased risk of suicidal thinking and behavior. The clinical need for an antidepressant in children or young adults for any use must be weighed against the risk of increased suicidally; patients who are started on therapy should be observed closely for clinical worsening, suicidally, or unusual changes in behavior, particularly within the first few months of starting therapy or at the time of dose increase or decrease; such observation would generally include at least weekly face-to-face contact with patients during the first 4 weeks of treatment, then every other week visits for the next 4 weeks, then at 12 weeks, and as clinically indicated beyond 12 weeks; additional contact by telephone may be appropriate between visits. It is unknown if the suicidally risk in children or young adults extends to longer-term therapy (i.e., beyond several months). The possibility of a suicide attempt is inherent in patients with depressive symptoms, whether these occur in primary depression or in association with another primary disorder. All patients with a history of suicidal ideation or behaviors and those with a prominence of suicidal ideation prior to treatment are considered at an increased risk for suicidal ideation or attempts, and should be closely monitored during treatment with duloxetine. In patients who exhibit changes in symptoms, worsening of depression or emergent suicidality, a decision should be made to change or discontinue treatment. If discontinuing, the medication should be tapered as rapidly as possible, but with recognition that abrupt discontinuation can also cause adverse symptoms. All antidepressants should be prescribed in the smallest quantity consistent with good patient management in order to reduce the risk of overdose. The potential for growth inhibition in pediatric patients should be monitored during duloxetine therapy. Monitor height and weight periodically while the patient is receiving duloxetine. Data are inadequate to determine whether the chronic use of SNRIs causes long-term growth inhibition; however, decreased weight gain has been observed in children and adolescents receiving duloxetine.

    DEA CLASS

    Rx

    DESCRIPTION

    Antidepressant of the serotonin norepinephrine reuptake inhibitor (SNRI) class.
    FDA approved for depression, fibromyalgia, diabetic peripheral neuropathy, chronic musculoskeletal pain, and generalized anxiety disorder (GAD) in adults; used off-label for stress urinary incontinence.
    FDA-approved for GAD in pediatric patients >= 7 years; however, clinical trials have not demonstrated efficacy for pediatric depression.
    Requires close monitoring in pediatrics and young adults due to increased risk of suicidality during the initial stages of treatment.

    COMMON BRAND NAMES

    Cymbalta, Irenka

    HOW SUPPLIED

    Cymbalta/Duloxetine/Irenka Oral Cap DR Pellets: 20mg, 30mg, 40mg, 60mg

    DOSAGE & INDICATIONS

    For the treatment of major depression.
    Oral dosage
    Adults

    Initially, 20 mg PO twice daily (40 mg/day) or 60 mg/day PO as a single dose or in 2 divided doses (i.e., 30 mg PO twice daily). An alternate regimen is 30 mg/day for 1 week followed by an increase to 60 mg/day. Use of a low initial daily dose (e.g., 30 to 40 mg/day) and/or dividing the total daily dose into 2 smaller doses (e.g., 20 to 30 mg twice daily) may increase tolerability, particularly in patients who have experienced adverse effects with other antidepressants or those patients with pre-existing conditions that may affect tolerability. Compliance should also be considered when deciding between a once daily and twice daily dosing regimen. The target maintenance dose is 60 mg/day. Max: 120 mg/day; however, doses greater than 60 mg/day have not shown additional benefit and higher doses may be associated with a higher rate of adverse events.

    For the treatment of generalized anxiety disorder (GAD).
    Oral dosage
    Adults

    Initially, 60 mg PO once daily. In some instances, it may be beneficial to begin therapy with 30 mg PO once daily for 1 week before increasing to 60 mg/day PO to allow for adjustment to the medication. Dosages up to 120 mg PO once daily are efficacious; however, there is currently no evidence to indicate a more beneficial effect with dosages greater than 60 mg/day PO. If doses greater than 60 mg/day PO are used, the increase should occur in increments of 30 mg/day. Max: 120 mg/day PO. Efficacy as monotherapy has been established for maintenance treatment of GAD. For patients requiring maintenance treatment, administer within the dosage range of 60 to 120 mg/day PO. Periodically re-evaluate the need for continued treatment.

    Children and Adolescents 7 years and older

    Initially, 30 mg PO once daily for 2 weeks. Thereafter, an increase to 60 mg/day PO may be considered. The recommended range is 30 to 60 mg PO once daily; however, some patients may benefit from doses higher than 60 mg/day PO. If doses higher than 60 mg/day PO are used, the increase should occur in increments of 30 mg/day PO. Max: 120 mg/day. In 1 clinical trial, the mean dose for patients completing the 10-week treatment phase was 57.6 mg/day.

    For the treatment of pain associated with diabetic neuropathy.
    Oral dosage
    Adults

    60 mg/day PO given as a single dose. A lower starting dose may be more appropriate in some patients. A clinical advantage of 60 mg/day vs. 60 mg twice a day dosing has not been demonstrated; and the higher dose is less well tolerated. In 12-week studies, the reduction in mean pain scores, was significant by the end of week 1. A response to treatment, defined as a 30% reduction from baseline in 24-hour average pain severity on a 0 to 10 scale, occurred in 63% of patients in the 60 mg/day group and 42% of patients receiving placebo. Secondary measures, such as global functioning and pain interference were found to be significant.

    For the treatment of pain associated with fibromyalgia.
    Oral dosage
    Adults

    Initially, 30 mg PO once daily for 1 week. Thereafter, increase to 60 mg PO once daily. Some patients may respond to 30 mg/day PO. Doses greater than 60 mg/day PO have not shown additional benefit. Efficacy for fibromyalgia in adults was established in 2 separate clinical trials (3 and 6 months duration, respectively). Study data suggest that pain reduction with duloxetine may be greater in those with comorbid major depressive disorder; although a significant reduction in pain scores also occurred in those without major depressive disorder.

    For the treatment of chronic musculoskeletal pain (e.g., chronic low back pain and chronic pain due to osteoarthritis).
    Oral dosage
    Adults

    60 mg PO once daily. In some instances, it may be beneficial to begin therapy with 30 mg PO once daily for 1 week before increasing to 60 mg/day PO to allow for adjustment to the medication. Patients who do not respond to 60 mg/day PO will not benefit from higher doses, and larger doses are associated with a higher rate of adverse reactions. Efficacy has not been established beyond 13 weeks.

    For the treatment of stress urinary incontinence† (SUI) in adult females.
    Oral dosage
    Adult females

    40 mg PO twice daily is the most commonly studied dosage. Duloxetine has been studied for the treatment of SUI in several phase III randomized, controlled trials worldwide, and is approved for SUI treatment in several European countries. Currently, there are no FDA-approved treatments for SUI in the US. The current body of literature for duloxetine shows significant but modest reductions in incontinence episode frequency (IEF) compared to placebo controls. However, this improvement does not consistently translate to formal incontinence-related quality of life (I-QOL) survey score improvement. Patients in the trials who continue the drug often rate personal satisfaction with therapy. Early side effects may cause a high rate of discontinuation. Nausea is common for an initial period of 1 to 4 weeks, after which nausea and GI complaints tend to resolve. Since there are limited pharmacologic and non-pharmacologic options for treating SUI, duloxetine therapy may be considered; as other commonly reported side effects (e.g., headache, constipation, dry mouth, dizziness, fatigue, and insomnia) are generally not severe.

    †Indicates off-label use

    MAXIMUM DOSAGE

    Adults

    120 mg/day PO.

    Geriatric

    120 mg/day PO.

    Adolescents

    120 mg/day PO for generalized anxiety disorder. Safety and efficacy for other indications have not been established.

    Children

    7 years and older: 120 mg/day PO for generalized anxiety disorder. Safety and efficacy for other indications have not been established.
    Less than 7 years: Safety and efficacy have not been established.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    Avoid use in patients with any chronic hepatic disease or cirrhosis, due to an increased risk for hepatotoxicity.

    Renal Impairment

    CrCl 30 mL/minute or more: No dosage adjustments are required.
    CrCl less than 30 mL/minute or eGFR less than 30 mL/min/1.73 m2: Avoid use in these patients or in those with renal failure or end-stage renal disease (on dialysis).

    ADMINISTRATION

    Oral Administration

    May be administered without regard to meals.

    Oral Solid Formulations

    Swallow whole; do not cut, chew, or crush capsules.

    STORAGE

    Cymbalta:
    - Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F
    Irenka:
    - Store at 77 degrees F; excursions permitted to 59-86 degrees F

    CONTRAINDICATIONS / PRECAUTIONS

    Abrupt discontinuation

    Avoid abrupt discontinuation of duloxetine if possible. Gradual tapering is recommended during discontinuation of any serotonin-norepinephrine reuptake inhibitor (SNRI) drug to decrease or prevent the occurrence of potential withdrawal symptoms. Withdrawal symptoms have been reported with abrupt discontinuation or tapering of duloxetine and have included abnormal dreams, headache, insomnia, dizziness, nausea/vomiting, paresthesia, irritability, fatigue, diarrhea, anxiety, vertigo, hyperhidrosis, and a small increase in recumbent heart rate. More severe symptoms such as confusion, hypomanic episode, and seizures have been reported following discontinuation of other SNRIs and similar medications. Patients should be carefully monitored if abrupt discontinuation of duloxetine becomes necessary.

    Closed-angle glaucoma, increased intraocular pressure

    Duloxetine is contraindicated in patients with uncontrolled closed-angle glaucoma. Caution is recommended when prescribing duloxetine to patients with controlled closed-angle glaucoma. In clinical trials, duloxetine was associated with an increased risk of mydriasis. The pupillary dilation that can occur with antidepressants may precipitate a closed-angle glaucoma in patients with anatomically narrow angles who do not have a patent iridectomy. An acute attack of closed-angle glaucoma is considered a medical emergency because the increased intraocular pressure is rapid and severe, and may quickly result in blindness if left untreated.

    Bipolar disorder, mania

    Duloxetine should be used cautiously in patients with a history of mania. All effective antidepressants can transform depression into mania in predisposed individuals. In placebo-controlled trials in patients with major depressive disorder, activation of mania or hypomania was reported in 0.1% of duloxetine-treated and placebo-treated patients. No activation of mania or hypomania was reported in placebo-controlled trials for the various indications for use. Activation of mania or hypomania has been reported in a small proportion of patients with mood disorders who were treated with other marketed drugs effective in the treatment of major depressive disorder. If a patient develops manic symptoms, duloxetine should be withheld, and appropriate therapy initiated to treat the manic symptoms. Additionally, depression may be the presenting symptom of a mixed/manic episode of bipolar disorder. Patients should be adequately screened for bipolar disorder prior to initiating an antidepressant. Such screening should include a detailed psychiatric history, including a family history of suicide, bipolar disorder, and depression. Patients with depression or comorbid depression in the setting of other psychiatric illness being treated with antidepressants should be observed for clinical worsening and suicidality, especially during the initial few months of a course of drug therapy, or at times of dose changes. Caregivers should be advised to closely observe the patient on a daily basis and to communicate immediately with the prescriber the emergence of agitation, irritability, unusual changes in behavior, or suicidality. It should be noted that duloxetine is not approved for use in treating bipolar depression.

    Children, growth inhibition, suicidal ideation

    Duloxetine is not recommended for use in children less than 7 years of age; safety and efficacy have not been established. Duloxetine is FDA-approved for use in children and adolescents 7 years and older with generalized anxiety disorder (GAD); efficacy for major depressive disorder was not established in two 10-week controlled trials with 800 pediatric patients (7 years and older). In October 2004, the FDA directed manufacturers of all antidepressants to include a boxed warning detailing the risk of suicide in pediatric patients. A causal role has been established for antidepressants in inducing suicidally in pediatric patients. The risk of suicidally for these drugs was identified in a pooled analysis of 24 placebo-controlled trials (n = 4400) lasting up to 16 weeks in pediatric patients with major depressive disorder (MDD), obsessive compulsive disorder (OCD), or other psychiatric disorders. The analysis showed a greater risk of suicidally during the first few months of treatment in those receiving antidepressants (SSRIs and others). The average risk of such events on drug was 4% and 2% for placebo; however, no suicides occurred in these trials. Pooled analysis of short-term clinical trials during early phase treatment with SSRIs and other antidepressants in young adults (18 to 24 years) also showed an increased risk of suicidal thinking and behavior. The clinical need for an antidepressant in children or young adults for any use must be weighed against the risk of increased suicidally; patients who are started on therapy should be observed closely for clinical worsening, suicidally, or unusual changes in behavior, particularly within the first few months of starting therapy or at the time of dose increase or decrease; such observation would generally include at least weekly face-to-face contact with patients during the first 4 weeks of treatment, then every other week visits for the next 4 weeks, then at 12 weeks, and as clinically indicated beyond 12 weeks; additional contact by telephone may be appropriate between visits. It is unknown if the suicidally risk in children or young adults extends to longer-term therapy (i.e., beyond several months). The possibility of a suicide attempt is inherent in patients with depressive symptoms, whether these occur in primary depression or in association with another primary disorder. All patients with a history of suicidal ideation or behaviors and those with a prominence of suicidal ideation prior to treatment are considered at an increased risk for suicidal ideation or attempts, and should be closely monitored during treatment with duloxetine. In patients who exhibit changes in symptoms, worsening of depression or emergent suicidality, a decision should be made to change or discontinue treatment. If discontinuing, the medication should be tapered as rapidly as possible, but with recognition that abrupt discontinuation can also cause adverse symptoms. All antidepressants should be prescribed in the smallest quantity consistent with good patient management in order to reduce the risk of overdose. The potential for growth inhibition in pediatric patients should be monitored during duloxetine therapy. Monitor height and weight periodically while the patient is receiving duloxetine. Data are inadequate to determine whether the chronic use of SNRIs causes long-term growth inhibition; however, decreased weight gain has been observed in children and adolescents receiving duloxetine.

    MAOI therapy

    Duloxetine is contraindicated for concomitant use in patients receiving MAOI therapy, due to the risk for serotonin syndrome. Duloxetine is a serotonin norepinephrine reuptake inhibitor (SNRI) and should not be used concurrently with MAOI therapy or within 14 days of discontinuation of a MAOI intended to treat a psychiatric disorder. Similarly, treatment with such MAOIs should not be initiated for at least 5 days after stopping duloxetine. In addition, do not start duloxetine in a patient who is being treated with linezolid or intravenous methylene blue. Serotonin syndrome has been reported with SNRIs, including duloxetine, both when taken alone, but especially when coadministered with other serotonergic agents (including triptans, selective serotonin reuptake inhibitors or SSRIs, tricyclic antidepressants, fentanyl, lithium, tramadol, tryptophan, buspirone, amphetamines, and St. John’s Wort). If such symptoms occur, discontinue duloxetine and initiate supportive treatment. If concomitant use of duloxetine with other serotonergic drugs is clinically warranted, patients should be made aware of a potential increased risk for serotonin syndrome, particularly during treatment initiation and dose increases.

    Electroconvulsive therapy (ECT), seizure disorder

    Duloxetine has not been systematically evaluated in patients with a seizure disorder, and such patients were excluded from clinical studies. In adult placebo-controlled clinical trials, seizures/convulsions occurred in 0.02% of patients treated with duloxetine and 0.01% of patients treated with placebo. Use with caution in patients with a history of a seizure disorder. Duloxetine's effects during electroconvulsive therapy (ECT) have not been evaluated in clinical studies.

    Cardiac disease, hypertension, hypotension, orthostatic hypotension, syncope

    Duloxetine has not been studied in patients with cardiac disease, including those with a recent history of myocardial infarction or unstable coronary artery disease. Blood pressure should be measured prior to initiating duloxetine treatment and periodically measured throughout treatment. Patients with preexisting hypotension should be cautioned appropriately and monitored closely if duloxetine therapy is initiated as orthostatic hypotension, syncope, and falls have been reported during duloxetine administration. Orthostatic hypotension and syncope are more likely during the first week of treatment or after dose increases. Other factors that may increase the risk of hypotension include use of duloxetine dosages above 60 mg/day and coadministration of potent CYP1A2 inhibitors or antihypertensive drugs. In an analysis of patients from all placebo-controlled trials, patients treated with duloxetine reported a higher rate of falls compared to patients treated with placebo. Risk appears to be related to the presence of orthostatic decrease in blood pressure. Falls resulting in bone fractures and hospitalizations have occurred during treatment with duloxetine. Consideration should be given to reducing the dose or discontinuing treatment in patients who experience falls, syncope, or symptomatic orthostasis. Also use duloxetine with caution in patients with preexisting hypertension, as duloxetine use has been associated with mild increases in heart rate and blood pressure during clinical study of doses within the usual dosage range. Mean elevations of 0.5 mmHg in systolic blood pressure (SBP) and 0.8 mmHg in diastolic blood pressure (DBP) were noted in patients receiving duloxetine across all indications in clinical study.

    Dehydration, hyponatremia, hypovolemia

    Serotonin norepinephrine reuptake inhibitors (SNRIs), such as duloxetine, may cause hyponatremia which is frequently the result of the syndrome of inappropriate antidiuretic hormone secretion (SIADH). In some cases, serum sodium levels less than 110 mmol/L have been reported; however, the adverse effect appeared reversible upon discontinuation of the causative SNRI. Elderly patients, those receiving diuretics or prone to dehydration, and those who are otherwise volume depleted (e.g., hypovolemia) appear to be at greatest risk. Hyponatremia may manifest as headache, difficulty concentrating, memory impairment, confusion, weakness, and unsteadiness which may result in falls. Severe manifestations include hallucinations, syncope, seizure, coma, respiratory arrest, and death. Symptomatic hyponatremia may require discontinuation of duloxetine, as well as implementation of the appropriate medical interventions.

    Alcoholism, hepatic disease, hepatitis, hepatotoxicity, jaundice

    Avoid use of duloxetine in patients with chronic hepatic disease or cirrhosis. Postmarketing reports suggest patients with pre-existing hepatic disease who take duloxetine may be at an increased risk for hepatotoxicity. There have been reports of hepatic failure, sometimes fatal, in patients treated with duloxetine. These cases have presented as hepatitis with abdominal pain, hepatomegaly, and elevation of transaminase levels to more than 20 times the upper limit of normal (ULN) with or without jaundice, reflecting a mixed or hepatocellular pattern of liver injury. Duloxetine should be discontinued in patients who develop jaundice or other evidence of clinically significant liver dysfunction and should not be resumed unless another cause can be established. Cases of cholestatic jaundice with minimal elevation of transaminase levels have also been reported. Other postmarketing reports indicate that elevated transaminases, bilirubin, and alkaline phosphatase have occurred in patients with chronic liver disease or cirrhosis. Duloxetine caused elevated liver function tests (LFTs) in clinical trials. Liver transaminase elevations resulted in drug discontinuation in 0.3% of treated patients. In most patients, the median time to detection of the transaminase elevation was about 2 months. In adult placebo-controlled trials in any indication, for patients with normal and abnormal baseline ALT values, ALT increased to more than 3 times the ULN occurred in 1.25% of duloxetine-treated patients compared to 0.45% for placebo. In adult placebo-controlled studies using a fixed dose design, there was evidence of a dose response relationship for ALT and AST elevation of more than 3 times the ULN and more than 5 times the ULN, respectively. Because it is possible that duloxetine and alcohol may interact to cause liver injury or that duloxetine may aggravate pre-existing liver disease, duloxetine should not be prescribed to patients with substantial alcohol use (alcoholism) or evidence of chronic hepatic disease.

    Serious rash

    Serious rash and other severe cutaneous reactions, including erythema multiforme and Stevens-Johnson Syndrome (SJS), can occur with duloxetine. The reporting rate of SJS associated with duloxetine use exceeds the general population background incidence rate for this serious skin reaction (1 to 2 cases per million person years). The reporting rate is generally accepted to be an underestimate due to underreporting. Duloxetine should be discontinued at the first appearance of blisters, peeling rash, mucosal erosions, or any other sign of hypersensitivity if no other etiology can be identified.

    Anticoagulant therapy, bleeding, thrombolytic therapy

    Monitor patients taking duloxetine for signs and symptoms of bleeding. Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage). Concurrent use of aspirin, NSAIDs, anticoagulant therapy, thrombolytic therapy, or other medications that enhance bleeding potential may increase this risk. Patients taking duloxetine should be instructed to promptly report any bleeding events to the practitioner.

    Renal failure, renal impairment

    Avoid use of duloxetine in patients with severe renal impairment (eGFR less than 30 mL/minute/1.73 m2). Increased plasma concentrations of duloxetine, and especially of its metabolites, occur in patients with end-stage renal disease and renal failure.

    Urinary retention

    Duloxetine is in a class of drugs known to affect urethral resistance. If symptoms of urinary hesitation develop during treatment with duloxetine, consider the possibility that they might be drug-related. In postmarketing experience, cases of urinary retention have been observed. In some instances of urinary retention associated with duloxetine use, hospitalization and/or catheterization has been needed.

    Driving or operating machinery, ethanol ingestion

    Because any psychoactive drug may impair judgment, thinking, or motor skills, patients should use caution when driving or operating machinery, until the full effect of duloxetine is determined. The use of other CNS-active agents may augment these effects. Duloxetine did not increase the impairment of mental and motor skills caused by alcohol. However, patients should be advised to limit ethanol ingestion while taking duloxetine, since excessive alcohol intake increases the risk for hepatotoxicity.

    Diabetes mellitus

    Monitor patients with diabetes mellitus for changes in glycemic control during duloxetine therapy. During long-term studies (up to 52 weeks) for the management of painful diabetic peripheral neuropathy, the mean blood glucose levels increased by 12 mg/dL in the duloxetine group and decreased by 11.5 mg/dL in the routine care group. In addition, the A1c increased by 0.5% in those treated with duloxetine and 0.2% in those receiving routine care. Additionally, the effects of altered motility on the stability of the enteric coating of duloxetine product is not known; however, rapid hydrolysis of the drug occurs in an acidic environment. Therefore, the manufacturer advises caution when using duloxetine in those with delayed gastric emptying, such as some patients with diabetes.

    Neonates, pregnancy

    There are no adequate and well-controlled studies on the use of duloxetine during human pregnancy. Duloxetine should be used in pregnancy only where the benefit to the mother clearly outweighs any potential risk to the fetus. Alternative agents should be considered. In animal reproduction studies, duloxetine has been shown to have adverse effects on embryo/fetal and postnatal development. Non-teratogenic effects have been reported in humans. Neonates exposed to serotonergic antidepressants late in the third trimester have developed complications requiring prolonged hospitalization, respiratory support, and tube feeding. Such complications can arise immediately upon delivery. Features are consistent with either a direct toxic effect of serotonergic agents or, possibly, a neonatal abstinence syndrome. It should be noted that, in some cases, the clinical picture is consistent with serotonin syndrome. When treating a pregnant woman with an SNRI or other serotonergic agent during the third trimester, the physician should carefully consider the potential risks and benefits of treatment. If clinically feasible, gradual tapering of the medication (in the mother) prior to delivery may be considered. Healthcare providers are encouraged to register patients exposed to duloxetine during pregnancy in the Cymbalta Pregnancy Registry at 1-866-814-6975 or by visiting the Cymbalta pregnancy registry website. Pregnancy outcomes of women exposed to duloxetine while pregnant are maintained in this registry.

    Breast-feeding

    Use caution when duloxetine is administered to a breast-feeding women. Duloxetine, a dual serotonin-norepinephrine reuptake inhibitor, is excreted into the breast milk of lactating women. The estimated daily infant dose is approximately 0.14% of the maternal dose. The disposition of duloxetine was studied in 6 lactating women who were at least 12 weeks postpartum and had elected to wean their infants. The women were given 40 mg of duloxetine twice daily for 3.5 days. The peak concentration measured in breast milk occurred at a median of 3 hours after the dose. The amount of duloxetine in breast milk was approximately 7 mcg/day while on that dose; the estimated daily infant dose was approximately 2 mcg/kg/day. The estimated daily infant dose is approximately 0.14% of the maternal dose. The presence of metabolites in breast milk was not examined. The developmental and health benefits of human milk feeding should be considered along with the mother’s clinical need for duloxetine and any potential adverse effects on the milk-fed infant from the drug or from the underlying maternal condition. A pooled analysis found that maternal use of sertraline, along with nortriptyline and paroxetine, usually produced undetectable or low drug concentrations in infant serum and, therefore, may be the preferred antidepressants in breast-feeding mothers. Consider the benefits of breast-feeding, the risk of potential drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding baby experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.

    Geriatric

    Use duloxetine with caution in the geriatric patient. Therapeutic use of duloxetine has resulted in orthostatic hypotension, syncope, and falls that, in some cases, have resulted in bone fractures and hospitalizations. The risk of falls is associated with the degree of orthostasis and any other factors that may increase the likelihood of falling (e.g., age-related risks, concomitant medications with orthostatic effects). Geriatric patients are more likely than younger adults to have a regimen of multiple medications, concomitant illnesses, and gait disturbances that may increase the underlying risk of falls. In addition, serotonin norepinephrine reuptake inhibitors (SNRIs) can cause or exacerbate hyponatremia, and the elderly may have an increased risk of developing low serum sodium levels compared to other age groups. Some geriatric patients may experience an increased sensitivity to other adverse effects of antidepressants including duloxetine. According to the Beers Criteria, serotonin norepinephrine reuptake inhibitors (SNRIs) are considered potentially inappropriate medications (PIMs) in older adults and should be used cautiously because SNRIs can cause or exacerbate hyponatremia and SIADH and the elderly are at increased risk of developing these conditions. Sodium levels should be closely monitored when starting or changing dosages in older adults. The Beers expert panel also recommends avoiding duloxetine in geriatric patients with a creatinine clearance less than 30 mL/min due to increased gastrointestinal effects (e.g., nausea, diarrhea). The federal Omnibus Budget Reconciliation Act (OBRA) regulates medication use in residents of long-term care facilities (LTCFs). According to the OBRA guidelines, the duration of therapy with an antidepressant should be in accordance with pertinent literature for the condition being treated, including clinical practice guidelines. All LTCF residents being treated for depression with any antidepressant should be monitored closely for worsening of depression and/or suicidal behavior or thinking, especially during initiation of therapy and during dose changes. Antidepressants may cause dizziness, nausea, diarrhea, anxiety, nervousness, insomnia, somnolence, weight gain, anorexia, or increased appetite. Many of these effects can increase the risk for falls. Prior to discontinuation, many antidepressants may need a taper to avoid a withdrawal syndrome. Concurrent use of 2 or more antidepressants may increase the risk of side effects; in such cases there should be documentation of expected benefits that outweigh the associated risks and monitoring for any increase in side effects. Monitoring should consist of a review for continued need at least quarterly, and documentation of the rationale for continuation. When the drug is being used to manage behavior, stabilize mood, or treat a psychiatric disorder, the facility should attempt to taper the medication as outlined in the OBRA guidelines, unless a taper is clinically contraindicated. During use to manage urinary incontinence, assessment of the underlying causes and identification of the type/category of urinary incontinence needs to be documented prior to or soon after initiating treatment. Medications for urinary incontinence have specific and limited indications based on the cause and categorization of incontinence. Patients should be assessed periodically for medication effects on urinary incontinence as well as lower urinary tract symptoms and treatment tolerability.

    ADVERSE REACTIONS

    Severe

    myocardial infarction / Delayed / 0.1-1.0
    visual impairment / Early / 0.1-1.0
    suicidal ideation / Delayed / 0.1-1.0
    GI bleeding / Delayed / 0.1-1.0
    peptic ulcer / Delayed / 0-0.1
    seizures / Delayed / 0-0.1
    pancreatitis / Delayed / Incidence not known
    erythema multiforme / Delayed / Incidence not known
    anaphylactoid reactions / Rapid / Incidence not known
    Stevens-Johnson syndrome / Delayed / Incidence not known
    vasculitis / Delayed / Incidence not known
    angioedema / Rapid / Incidence not known
    hepatic failure / Delayed / Incidence not known
    hypertensive crisis / Early / Incidence not known
    ocular hypertension / Delayed / Incidence not known
    SIADH / Delayed / Incidence not known
    hyperkalemia / Delayed / Incidence not known
    serotonin syndrome / Delayed / Incidence not known
    neonatal abstinence syndrome / Early / Incidence not known

    Moderate

    constipation / Delayed / 9.0-11.0
    impotence (erectile dysfunction) / Delayed / 4.0-4.0
    ejaculation dysfunction / Delayed / 2.0-3.0
    blurred vision / Early / 3.0-3.0
    palpitations / Early / 0-2.0
    elevated hepatic enzymes / Delayed / 1.1-1.1
    myoclonia / Delayed / 0.1-1.0
    confusion / Early / 0.1-1.0
    dyskinesia / Delayed / 0.1-1.0
    gastritis / Delayed / 0.1-1.0
    stomatitis / Delayed / 0.1-1.0
    teeth grinding (bruxism) / Delayed / 0.1-1.0
    dehydration / Delayed / 0.1-1.0
    erythema / Early / 0.1-1.0
    contact dermatitis / Delayed / 0.1-1.0
    hot flashes / Early / 0.1-1.0
    dysuria / Early / 0.1-1.0
    orthostatic hypotension / Delayed / 0.1-1.0
    sinus tachycardia / Rapid / 0.1-1.0
    hypotension / Rapid / 0.1-1.0
    hypothyroidism / Delayed / 0.1-1.0
    dysarthria / Delayed / 0-0.1
    mania / Early / 0.1-0.1
    withdrawal / Early / 1.0
    hyperglycemia / Delayed / Incidence not known
    trismus / Delayed / Incidence not known
    hallucinations / Early / Incidence not known
    colitis / Delayed / Incidence not known
    urinary retention / Early / Incidence not known
    hepatomegaly / Delayed / Incidence not known
    hyperbilirubinemia / Delayed / Incidence not known
    hepatitis / Delayed / Incidence not known
    jaundice / Delayed / Incidence not known
    cholestasis / Delayed / Incidence not known
    hypertension / Early / Incidence not known
    supraventricular tachycardia (SVT) / Early / Incidence not known
    depression / Delayed / Incidence not known
    akathisia / Delayed / Incidence not known
    hostility / Early / Incidence not known
    impulse control symptoms / Delayed / Incidence not known
    hyponatremia / Delayed / Incidence not known
    hematoma / Early / Incidence not known
    platelet dysfunction / Delayed / Incidence not known
    bleeding / Early / Incidence not known
    galactorrhea / Delayed / Incidence not known
    hyperprolactinemia / Delayed / Incidence not known
    hypokalemia / Delayed / Incidence not known
    hypercholesterolemia / Delayed / Incidence not known

    Mild

    nausea / Early / 4.0-24.0
    headache / Early / 13.0-18.0
    xerostomia / Early / 2.0-14.0
    weight loss / Delayed / 0.1-14.0
    abdominal pain / Early / 5.0-13.0
    drowsiness / Early / 9.0-12.0
    asthenia / Delayed / 10.0-11.0
    fatigue / Early / 7.0-11.0
    insomnia / Early / 7.0-11.0
    dizziness / Early / 8.0-10.0
    anorexia / Delayed / 7.0-10.0
    vomiting / Early / 4.0-9.0
    diarrhea / Early / 6.0-9.0
    hyperhidrosis / Delayed / 0-6.0
    agitation / Early / 4.0-5.0
    restlessness / Early / 4.0-5.0
    musculoskeletal pain / Early / 4.0-4.0
    myalgia / Early / 4.0-4.0
    pharyngitis / Delayed / 4.0-4.0
    infection / Delayed / 4.0-4.0
    back pain / Delayed / 3.0-3.0
    tremor / Early / 0-3.0
    anxiety / Delayed / 0-3.0
    flushing / Rapid / 0-3.0
    libido decrease / Delayed / 3.0-3.0
    cough / Delayed / 3.0-3.0
    nightmares / Early / 0-2.0
    yawning / Early / 2.0-2.0
    hypoesthesia / Delayed / 2.0-2.0
    dyspepsia / Early / 2.0-2.0
    orgasm dysfunction / Delayed / 1.0-2.0
    influenza / Delayed / 2.0-2.0
    irritability / Delayed / 0.1-1.0
    tinnitus / Delayed / 0.1-1.0
    otalgia / Early / 0.1-1.0
    malaise / Early / 0.1-1.0
    halitosis / Early / 0.1-1.0
    eructation / Early / 0.1-1.0
    polydipsia / Early / 0.1-1.0
    photosensitivity / Delayed / 0.1-1.0
    night sweats / Early / 0.1-1.0
    polyuria / Early / 0.1-1.0
    nocturia / Early / 0.1-1.0
    increased urinary frequency / Early / 0.1-1.0
    syncope / Early / 0.1-1.0
    diplopia / Early / 0.1-1.0
    xerophthalmia / Early / 0.1-1.0
    menstrual irregularity / Delayed / 0-0.1
    laryngitis / Delayed / 0-0.1
    ecchymosis / Delayed / 0-0.1
    dysgeusia / Early / 1.0
    vertigo / Early / 1.0
    lethargy / Early / 1.0
    flatulence / Early / 1.0
    weight gain / Delayed / 1.0
    pruritus / Rapid / 1.0
    chills / Rapid / 1.0
    muscle cramps / Delayed / Incidence not known
    restless legs syndrome (RLS) / Delayed / Incidence not known
    paresthesias / Delayed / Incidence not known
    rash (unspecified) / Early / Incidence not known
    urticaria / Rapid / Incidence not known
    mydriasis / Early / Incidence not known
    epistaxis / Delayed / Incidence not known
    petechiae / Delayed / Incidence not known

    DRUG INTERACTIONS

    Abciximab: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) like duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving abciximab. Monitor the patient closely for signs and symptoms of bleeding.
    Acebutolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of acebutolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Acetaminophen; Aspirin, ASA; Caffeine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Acetaminophen; Caffeine; Magnesium Salicylate; Phenyltoloxamine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Acetaminophen; Caffeine; Phenyltoloxamine; Salicylamide: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Acetaminophen; Dextromethorphan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Acetaminophen; Dextromethorphan; Doxylamine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Acetaminophen; Dextromethorphan; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Acetaminophen; Dextromethorphan; Pseudoephedrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Acetaminophen; Hydrocodone: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Acetaminophen; Pentazocine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as pentazocine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Acetaminophen; Tramadol: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tramadol. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. In one case, the addition of tramadol to extended-release venlafaxine (300 mg/day) and mirtazapine (30 mg/day) likely caused serotonin syndrome. A patient developed agitation, confusion, severe shivering, diaphoresis, myoclonus, hyperreflexia, mydriasis, tachycardia, and fever within 7 weeks of taking tramadol 400 mg daily. He had taken 300 mg tramadol without difficulty. Discontinuation of the 3 drugs and rehydration led to symptom resolution over 36 hours. Reinstitution of the antidepressants 3 days after patient presentation was uneventful. Also, duloxetine may inhibit the formation of the active M1 metabolite of tramadol by inhibiting CYP2D6. The inhibition of this metabolite may decrease the analgesic effectiveness of tramadol but increase the level of the parent compound, which has more serotonergic activity than the metabolite. The risk for serious adverse effects such as seizures and serotonin syndrome may be increased. Patients receiving tramadol in combination with an SNRI should be monitored for the emergence of serotonin syndrome, neuroleptic malignant syndrome-like reactions, or other adverse effects.
    Aliskiren: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Aliskiren; Amlodipine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Aliskiren; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Aliskiren; Valsartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Alteplase, tPA: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Ambrisentan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Aminosalicylate sodium, Aminosalicylic acid: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Amiodarone: (Moderate) Monitor for adverse effects associated with increased exposure to duloxetine if amiodarone is coadministered. Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of amiodarone and duloxetine may increase the risk of hypotension; monitor blood pressure if the combination is necessary. Amiodarone is a CYP1A2 and CYP2D6 inhibitor, while duloxetine is a CYP1A2 and CYP2D6 substrate.
    Amitriptyline: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Clinicians should also be alert for pharmacokinetic interactions between tricyclic antidepressants and SNRIs. Duloxetine and venlafaxine are inhibitors of CYP2D6, and many TCAs are metabolized by this isozyme. Duloxetine increased the maximum plasma concentration (Cmax) of desipramine 1.7-fold and the AUC 2.9-fold in one study. One case report documented a first-time seizure in a patient receiving venlafaxine and trimipramine at therapeutic dosages. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or other adverse effects. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Amitriptyline; Chlordiazepoxide: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Clinicians should also be alert for pharmacokinetic interactions between tricyclic antidepressants and SNRIs. Duloxetine and venlafaxine are inhibitors of CYP2D6, and many TCAs are metabolized by this isozyme. Duloxetine increased the maximum plasma concentration (Cmax) of desipramine 1.7-fold and the AUC 2.9-fold in one study. One case report documented a first-time seizure in a patient receiving venlafaxine and trimipramine at therapeutic dosages. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or other adverse effects. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Amlodipine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Amlodipine; Atorvastatin: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Amlodipine; Benazepril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Amlodipine; Hydrochlorothiazide, HCTZ; Olmesartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Amlodipine; Hydrochlorothiazide, HCTZ; Valsartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Amlodipine; Olmesartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Amlodipine; Telmisartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Amlodipine; Valsartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Amoxapine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have central serotonergic properties such as amoxapine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. In addition, duloxetine is a moderate inhibitor of CYP2D6, and amoxapine is partially metabolized by this isoenzyme. It is possible that duloxetine could increase the risk of cyclic antidepressant-related side effects or toxicity.
    Amphetamine; Dextroamphetamine Salts: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as amphetamines. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. In addition, the MAOI activity of amphetamines may be of concern with the use of drugs that have serotonergic activity. A man developed marked agitation, anxiety, diaphoresis, shivering, tachycardia, tremor, generalized hypertonia, hyperreflexia, 1 to 2 beats of inducible ankle clonus, frequent myoclonic jerking, and tonic spasm of the right side of his orbicularis oris muscle while taking dexamphetamine and venlafaxine. Cessation of both drugs and administration of cyproheptadine led to a stepwise heart rate reduction and complete symptom resolution. Patients receiving SNRIs and amphetamines should be monitored for the emergence of serotonin syndrome, particularly during treatment initiation and during dosage increases. The SNRI and amphetamine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Anagrelide: (Moderate) Anagrelide has been shown to inhibit CYP1A2. In theory, coadministration of anagrelide with substrates of CYP1A2, including duloxetine, could lead to increases in the serum concentrations of these drugs and, thus, adverse effects. Patients receiving anagrelide and duloxetine concomitantly should be monitored for increased toxicity of duloxetine. Monitor the patient for signs of excessive serotonin activity. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Angiotensin II receptor antagonists: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Angiotensin-converting enzyme inhibitors: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Anticoagulants: (Major) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving anticoagulants. Elevations in prothrombin time, activated partial thromboplastin and INR values have been reported post-marketing when venlafaxine was added to established warfarin therapy. The causality and mechanism of this potential interaction have not been established. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with an anticoagulant medication and to promptly report any bleeding events to the practitioner.
    Aripiprazole: (Moderate) Because aripiprazole is partially metabolized by CYP2D6, increased aripiprazole plasma concentrations may occur during concurrent use of moderate inhibitors of CYP2D6, such as duloxetine. If these agents are used in combination, the patient should be carefully monitored for aripiprazole-related adverse reactions. Because aripiprazole is also metabolized by CYP3A4, patients receiving a combination of a CYP3A4 and CYP2D6 inhibitor should have their oral aripiprazole dose reduced to one-quarter (25%) of the usual dose with subsequent adjustments based upon clinical response. Adults receiving a combination of a CYP3A4 and CYP2D6 inhibitor for more than 14 days should have their Abilify Maintena dose reduced from 400 mg/month to 200 mg/month or from 300 mg/month to 160 mg/month, respectively. There are no dosing recommendations for Aristada during use of a mild to moderate CYP2D6 inhibitor. Aripiprazole dosage adjustments are not required when aripiprazole is added as adjunctive treatment to antidepressants for major depressive disorder provided that the manufacturer's dosing guidelines for this indication are followed.
    Artemether; Lumefantrine: (Moderate) Lumefantrine is an inhibitor and duloxetine is a substrate/inhibitor of the CYP2D6 isoenzyme; therefore, coadministration may lead to increased duloxetine concentrations. Concomitant use warrants caution due to the potential for increased side effects.
    Asenapine: (Moderate) Duloxetine is an inhibitor of CYP2D6 and CYP1A2 and may decrease the clearance of atypical antipsychotics that are CYP2D6 and CYP1A2 substrates including asenapine. Decreased metabolism of asenapine may lead to adverse reactions such as extrapyramidal symptoms. In addition, asenapine is associated with a risk for QT prolongation and torsade de pointes (TdP) and should be used cautiously with CYP2D6 and CYP1A2 inhibitors such as duloxetine. In vitro studies indicate that CYP1A2 is a primary metabolic pathway of asenapine.
    Aspirin, ASA: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Butalbital; Caffeine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Butalbital; Caffeine; Codeine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Caffeine; Dihydrocodeine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Carisoprodol: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Carisoprodol; Codeine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Dipyridamole: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner. (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Omeprazole: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Oxycodone: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Pravastatin: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Atazanavir; Cobicistat: (Moderate) Caution is warranted when cobicistat is administered with duloxetine as there is a potential for elevated duloxetine and cobicistat concentrations. Duloxetine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Atenolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of atenolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Atenolol; Chlorthalidone: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of atenolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Atomoxetine: (Moderate) Patients should be monitored for adverse effects associated with atomoxetine administration, such as nausea/vomiting, drowsiness, fatigue, abdominal pain, or decreased appetite, during concurrent use of duloxetine. A dosage adjustment of atomoxetine may be needed in normal populations (also known as extensive metabolizers) when atomoxetine is administered with inhibitors of the CYP2D6 enzyme. Atomoxetine is primarily a substrate for the cytochrome P450 isozyme CYP2D6. In vitro studies suggest that coadministration of CYP2D6 inhibitors to poor metabolizers will not further increase the plasma concentrations of atomoxetine.
    Atropine; Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Severe) Concurrent use of methylene blue and serotonin norepinephrine reuptake inhibitors (SNRIs) (e.g., venlafaxine, duloxetine, desvenlafaxine, milnacipran) should generally be avoided due to the potential for serotonin syndrome. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with serotonergic agents such as SNRIs may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent in parathyroid surgery, in patients receiving selective serotonin reuptake inhibitors, SNRIs, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with intravenous methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case report suggests that serotonin toxicity may have occurred post-operatively following administration of standard infusions of methylene blue in a patient receiving duloxetine. The patient experienced disorientation, a mildly elevated temperature, tachycardia, elevated blood pressure, mild agitation, and nystagmus. In a separate case, a patient who had been receiving venlafaxine developed expressive aphasia, confusion, and disinhibition following a methylene blue infusion. The authors concluded that methylene blue toxicity had occurred; however, they did not exclude the possibility of a drug interaction based upon previous reports of an interaction between injectable methylene blue and selective serotonin reuptake inhibitors (SSRIs). Published interaction reports between intravenously administered methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and/or coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. If emergent treatment with methylene blue is required in a patient receiving an SNRI, the SNRI must be stopped immediately and the patient should be monitored for symptoms of CNS toxicity for two weeks or until 24 hours after the last dose of methylene blue, whichever comes first. During non-emergent use of methylene blue, the SNRI should be stopped at least 2 weeks prior to methylene blue treatment, but also taking into consideration the half-life of the SNRI being discontinued. (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Azilsartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Azilsartan; Chlorthalidone: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Benazepril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Bendroflumethiazide; Nadolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of nadolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Severe) Concurrent use of methylene blue and serotonin norepinephrine reuptake inhibitors (SNRIs) (e.g., venlafaxine, duloxetine, desvenlafaxine, milnacipran) should generally be avoided due to the potential for serotonin syndrome. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with serotonergic agents such as SNRIs may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent in parathyroid surgery, in patients receiving selective serotonin reuptake inhibitors, SNRIs, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with intravenous methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case report suggests that serotonin toxicity may have occurred post-operatively following administration of standard infusions of methylene blue in a patient receiving duloxetine. The patient experienced disorientation, a mildly elevated temperature, tachycardia, elevated blood pressure, mild agitation, and nystagmus. In a separate case, a patient who had been receiving venlafaxine developed expressive aphasia, confusion, and disinhibition following a methylene blue infusion. The authors concluded that methylene blue toxicity had occurred; however, they did not exclude the possibility of a drug interaction based upon previous reports of an interaction between injectable methylene blue and selective serotonin reuptake inhibitors (SSRIs). Published interaction reports between intravenously administered methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and/or coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. If emergent treatment with methylene blue is required in a patient receiving an SNRI, the SNRI must be stopped immediately and the patient should be monitored for symptoms of CNS toxicity for two weeks or until 24 hours after the last dose of methylene blue, whichever comes first. During non-emergent use of methylene blue, the SNRI should be stopped at least 2 weeks prior to methylene blue treatment, but also taking into consideration the half-life of the SNRI being discontinued. (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Benzphetamine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as amphetamines. 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. In addition, the MAOI activity of amphetamines may be of concern with the use of drugs that have serotonergic activity. A man developed marked agitation, anxiety, diaphoresis, shivering, tachycardia, tremor, generalized hypertonia, hyperreflexia, 12 beats of inducible ankle clonus, frequent myoclonic jerking, and tonic spasm of the right side of his orbicularis oris muscle while taking dexamphetamine and venlafaxine. Cessation of both drugs and administration of cyproheptadine led to a stepwise heart rate reduction and complete symptom resolution. Patients receiving an SNRI and an amphetamine should be monitored for the emergence of serotonin syndrome, particularly during treatment initiation and during dosage increases. The SNRI and amphetamine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Betaxolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of betaxolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Bismuth Subsalicylate: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Bismuth Subsalicylate; Metronidazole; Tetracycline: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Bisoprolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of bisoprolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of bisoprolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Bosentan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Brexpiprazole: (Moderate) Because brexpiprazole is primarily metabolized by CYP3A4 and CYP2D6, the manufacturer recommends that the brexpiprazole dose be reduced to one-quarter (25%) of the usual dose in patients receiving a moderate to strong inhibitor of CYP3A4 in combination with a moderate to strong inhibitor of CYP2D6. Duloxetine is a moderate inhibitor of CYP2D6. If duloxetine is used in combination with brexpiprazole and a moderate to strong CYP3A4 inhibitor, the brexpiprazole dose should be adjusted and the patient should be carefully monitored for brexpiprazole-related adverse reactions.
    Brimonidine; Timolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of timolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Bromocriptine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as bromocriptine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Brompheniramine; Dextromethorphan; Guaifenesin: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Brompheniramine; Guaifenesin; Hydrocodone: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Brompheniramine; Hydrocodone; Pseudoephedrine: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Buprenorphine: (Major) Concurrent use of opioids, such as buprenorphine, with other drugs that modulate serotonergic function, such as SNRIs, has resulted in serotonin syndrome in some cases. 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. If combination treatment is required, patients should be carefully observed, particularly during treatment initiation and during dose adjustments of the serotonergic drug; discontinue buprenorphine if serotonin syndrome is suspected.
    Buprenorphine; Naloxone: (Major) Concurrent use of opioids, such as buprenorphine, with other drugs that modulate serotonergic function, such as SNRIs, has resulted in serotonin syndrome in some cases. 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. If combination treatment is required, patients should be carefully observed, particularly during treatment initiation and during dose adjustments of the serotonergic drug; discontinue buprenorphine if serotonin syndrome is suspected.
    Buspirone: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as buspirone. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Cabergoline: (Moderate) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties, such as cabergoline. Cabergoline has minimal affinity for serotonin receptors, possibly reducing the risk of this interaction compared to the chemically related ergot alkaloids. However, patients receiving cabergoline with an SNRI should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Calcium-channel blockers: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Candesartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Candesartan; Hydrochlorothiazide, HCTZ: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Captopril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Captopril; Hydrochlorothiazide, HCTZ: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Carbinoxamine; Dextromethorphan; Pseudoephedrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Carbinoxamine; Hydrocodone; Phenylephrine: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Carbinoxamine; Hydrocodone; Pseudoephedrine: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Carteolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of carteolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Carvedilol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of carvedilol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Celecoxib: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Central-acting adrenergic agents: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Chlorpheniramine; Dextromethorphan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Chlorpheniramine; Dextromethorphan; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Chlorpheniramine; Guaifenesin; Hydrocodone; Pseudoephedrine: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Chlorpheniramine; Hydrocodone: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Chlorpheniramine; Hydrocodone; Phenylephrine: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Chlorpheniramine; Hydrocodone; Pseudoephedrine: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Chlorpromazine: (Moderate) Caution is advisable during concurrent use of chlorpromazine and serotonin norepinephrine reuptake inhibitors (SNRIs) since elevations in plasma concentrations of chlorpromazine may occur. Phenothiazines are CYP2D6 substrates and duloxetine is a CYP2D6 inhibitor. In addition, chlorpromazine is associated with a possible risk of QT prolongation; therefore, cardiac effects are possible.
    Chlorthalidone; Clonidine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Choline Salicylate; Magnesium Salicylate: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Cilostazol: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Cimetidine: (Moderate) Use caution during coadministration of duloxetine and cimetidine; duloxetine concentrations may be increased. Duloxetine is a CYP1A2 substrate; cimetidine is a weak CYP1A2 inhibitor.
    Ciprofloxacin: (Major) Coadministration of duloxetine and potent inhibitors of CYP1A2, such as ciprofloxacin, should be avoided. Duloxetine is partially metabolized by CYP1A2. One study involving a potent CYP1A2 inhibitor in concomitant use with duloxetine showed that duloxetine exposure was significantly increased.
    Citalopram: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine, desvenlafaxine, duloxetine, and milnacipran. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome.
    Clevidipine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Clobazam: (Major) A dosage reduction of CYP2D6 substrates, such as duloxetine, may be necessary during co-administration of clobazam. Limited in vivo data suggest that clobazam is an inhibitor of CYP2D6. If these agents are used in combination, it is advisable to monitor the patient for adverse reactions related to duloxetine.
    Clomipramine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Clinicians should also be alert for pharmacokinetic interactions between tricyclic antidepressants and SNRIs. Duloxetine and venlafaxine are inhibitors of CYP2D6, and many TCAs are metabolized by this isozyme. Duloxetine increased the maximum plasma concentration (Cmax) of desipramine 1.7-fold and the AUC 2.9-fold in one study. One case report documented a first-time seizure in a patient receiving venlafaxine and trimipramine at therapeutic dosages. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or other adverse effects. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Clonidine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Clopidogrel: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Clozapine: (Moderate) Duloxetine is an inhibitor of CYP2D6 and CYP1A2, two of the isoenzymes responsible for the metabolism of clozapine. Treatment with clozapine has been associated with QT prolongation, torsade de pointes (TdP), cardiac arrest, and sudden death. Elevated plasma concentrations of clozapine occurring through CYP inhibition may potentially increase the risk of life-threatening arrhythmias, sedation, anticholinergic effects, seizures, orthostasis, or other adverse effects. According to the manufacturer, patients receiving clozapine in combination with an inhibitor of CYP1A2, CYP3A4, or CYP2D6 should be monitored for adverse reactions. Consideration should be given to reducing the clozapine dose if necessary. If the inhibitor is discontinued after dose adjustments are made, monitor for lack of clozapine effectiveness and consider increasing the clozapine dose if necessary.
    Cobicistat: (Moderate) Caution is warranted when cobicistat is administered with duloxetine as there is a potential for elevated duloxetine and cobicistat concentrations. Duloxetine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Cobicistat; Elvitegravir; Emtricitabine; Tenofovir Alafenamide: (Moderate) Caution is warranted when cobicistat is administered with duloxetine as there is a potential for elevated duloxetine and cobicistat concentrations. Duloxetine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Cobicistat; Elvitegravir; Emtricitabine; Tenofovir Disoproxil Fumarate: (Moderate) Caution is warranted when cobicistat is administered with duloxetine as there is a potential for elevated duloxetine and cobicistat concentrations. Duloxetine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Cyclobenzaprine: (Major) Cautious use of cyclobenzaprine and drugs that increase serotonin concentrations such as serotonin norepinephrine reuptake inhibitors (SNRIs) is advised because of the possibility of serotonin syndrome. If these drugs must be used together, closely monitor the patient for signs and symptoms of serotonin syndrome. If such a reaction develops, immediately discontinue cyclobenzaprine and the SSRI. A suspected case of serotonin syndrome was noted in a man who took duloxetine, opiates, and cyclobenzaprine. The man developed worsening confusion, hallucinations, diaphoresis, tachycardia, tremors, marked agitation, spontaneous sustained clonus, and multifocal myoclonus.but recovered after duloxetine and cyclobenzaprine discontinuation and cyproheptadine initiation. In addition, cyclobenzaprine is structurally similar to tricyclic antidepressants (TCAs) and like TCAs, is associated with a possible risk of QT prolongation and torsades de pointes (TdP), particularly in the event of acute overdose. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously with cyclobenzaprine include venlafaxine and potentially other SNRIs.
    Darifenacin: (Moderate) Duloxetine, a CYP2D6 inhibitor, may decrease the metabolism of darifenacin, a CYP2D6 substrate. Clinicians should monitor patients for increased anticholinergic effects when CYP2D6 inhibitors are coadministered with darifenacin; dosage adjustments of darifenacin may be necessary.
    Darunavir; Cobicistat: (Moderate) Caution is warranted when cobicistat is administered with duloxetine as there is a potential for elevated duloxetine and cobicistat concentrations. Duloxetine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Desipramine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Clinicians should also be alert for pharmacokinetic interactions between tricyclic antidepressants and SNRIs. Duloxetine and venlafaxine are inhibitors of CYP2D6, and many TCAs are metabolized by this isozyme. Duloxetine increased the maximum plasma concentration (Cmax) of desipramine 1.7-fold and the AUC 2.9-fold in one study. One case report documented a first-time seizure in a patient receiving venlafaxine and trimipramine at therapeutic dosages. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or other adverse effects. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Desvenlafaxine: (Severe) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, serotonin norepinephrine reuptake inhibitors (SNRIs) including venlafaxine, desvenlafaxine, duloxetine, levomilnacipran, and milnacipran should not be coadministered with each other. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SNRI to another SNRI.
    Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Dexmethylphenidate: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when coadministering drugs that have serotonergic properties such as dexmethylphenidate and serotonin norepinephrine reuptake inhibitors (SNRIs). There are rare reports of serotonin syndrome occurring during use of other serotonergic antidepressants (i.e., SSRIs) and methylphenidate, a racemic compound containing dexmethylphenidate. There is also a case of a neuroleptic malignant syndrome-like reaction occurring in a child on chronic methylphenidate therapy 45 minutes after ingesting a dose of venlafaxine. It is unclear if the reaction was the result of a drug interaction. 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. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. If serotonin syndrome occurs, all serotonergic agents should be discontinued and appropriate medical management should be implemented.
    Dextromethorphan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Dextromethorphan; Diphenhydramine; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Dextromethorphan; Guaifenesin: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Dextromethorphan; Guaifenesin; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Dextromethorphan; Guaifenesin; Potassium Guaiacolsulfonate: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Dextromethorphan; Guaifenesin; Pseudoephedrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Dextromethorphan; Promethazine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Dextromethorphan; Quinidine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Diazoxide: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Diclofenac: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Diclofenac; Misoprostol: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Diflunisal: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Diltiazem: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Diphenhydramine; Hydrocodone; Phenylephrine: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Diphenhydramine; Ibuprofen: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Diphenhydramine; Naproxen: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Dipyridamole: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Disulfiram: (Moderate) Co-administration of duloxetine and potent inhibitors of CYP1A2 should be avoided. Duloxetine is partially metabolized by CYP1A2. One study involving a potent CYP1A2 inhibitor in concomitant use with duloxetine showed that duloxetine exposure was significantly increased. Concurrent use of duloxetine and disulfiram, a CYP1A2 inhibitor, may result in excessive serotonin activity. Careful monitoring is recommended if concurrent therapy is considered necessary.
    Diuretics: (Moderate) Patients receiving a diuretic during treatment with venlafaxine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH may occur during therapy with SNRIs, including venlafaxine. Cases involving serum sodium levels lower than 110 mmol/l have been reported. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of the SNRI should be considered in patients who develop symptomatic hyponatremia.
    Dolasetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering dolasetron with other drugs that have serotonergic properties such as duloxetine. If serotonin syndrome is suspected, discontinue dolasetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Dorzolamide; Timolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of timolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Doxazosin: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Doxepin: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Clinicians should also be alert for pharmacokinetic interactions between tricyclic antidepressants and SNRIs. Duloxetine and venlafaxine are inhibitors of CYP2D6, and many TCAs are metabolized by this isozyme. Duloxetine increased the maximum plasma concentration (Cmax) of desipramine 1.7-fold and the AUC 2.9-fold in one study. One case report documented a first-time seizure in a patient receiving venlafaxine and trimipramine at therapeutic dosages. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or other adverse effects. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Doxercalciferol: (Moderate) Doxercalciferol is converted in the liver to 1,25-dihydroxyergocalciferol, the major active metabolite, and 1-alpha, 24-dihydroxyvitamin D2, a minor metabolite. Although not specifically studied, cytochrome P450 enzyme inhibitors including duloxetine may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if duloxetine is coadministered with doxercalciferol.
    Doxorubicin: (Major) Duloxetine is a CYP2D6 inhibitor and doxorubicin is a major CYP2D6 substrate. Clinically significant interactions have been reported when doxorubicin was coadministered with inhibitors of CYP2D6, resulting in increased concentration and clinical effect of doxorubicin. Avoid coadministration of duloxetine and doxorubicin if possible. If not possible, closely monitor for increased side effects of doxorubicin including myelosuppression and cardiotoxicity.
    Dutasteride; Tamsulosin: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as duloxetine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
    Eliglustat: (Major) In extensive or intermediate CYP2D6 metabolizers (EMs or IMs), coadministration of duloxetine and eliglustat requires dosage reduction of eliglustat to 84 mg PO once daily; however, coadministration of eliglustat with both duloxetine and a strong or moderate CYP3A inhibitor is contraindicated. Duloxetine is a CYP2D6 substrate and moderate inhibitor; eliglustat is a CYP2D6 and CYP3A substrate and a CYP2D6 inhibitor. Coadministration with CYP2D6 inhibitors may increase eliglustat exposure and the risk of serious adverse events (e.g., QT prolongation and cardiac arrhythmias). In addition, coadministration of eliglustat with CYP2D6 substrates (e.g., duloxetine) may result in increased concentrations of the concomitant drug; monitor patients closely for adverse events, and consider reducing the dosage of duloxetine and titrating to clinical effect.
    Enalapril, Enalaprilat: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Enalapril; Felodipine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Eplerenone: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Epoprostenol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Eprosartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Eprosartan; Hydrochlorothiazide, HCTZ: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Eptifibatide: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Ergot alkaloids: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as ergot alkaloids. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Escitalopram: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine, desvenlafaxine, duloxetine, and milnacipran. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome.
    Esmolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of esmolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Esomeprazole; Naproxen: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Estrogens: (Minor) Estrogens are partially metabolized by CYP3A4. Drugs that inhibit CYP3A4 such as duloxetine may increase plasma concentrations of estrogens and cause estrogen-related side effects such as nausea and breast tenderness. Patients receiving estrogens should be monitored for an increase in adverse events.
    Ethanol: (Major) Although duloxetine does not appear to increase the impairment of mental and motor skills caused by ethanol, substantial ethanol consumption during treatment with duloxetine has resulted in severe, and sometimes fatal, hepatotoxicity. Duloxetine should not be prescribed to patients with substantial ethanol use.
    Etodolac: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Famotidine; Ibuprofen: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Felodipine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Fenoldopam: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Fenoprofen: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Fentanyl: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering duloxetine with other drugs that have serotonergic properties such as fentanyl. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring is recommended during co-administration of fentanyl and duloxetine for signs and symptoms of serotonin syndrome or other serious effects.
    Fluoxetine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine, desvenlafaxine, duloxetine, and milnacipran. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome.
    Fluoxetine; Olanzapine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine, desvenlafaxine, duloxetine, and milnacipran. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. (Moderate) Duloxetine is an inhibitor of CYP1A2 and CYP2D6 and should be used cautiously with atypical antipsychotics metabolized by CYP1A2 and CYP2D6 such as olanzapine. Plasma concentrations of atypical antipsychotics primarily metabolized via CYP1A2, such as olanzapine, may increase substantially during concurrent use. Decreased metabolism of olanzapine may lead to clinically important adverse reactions, such as orthostatic hypotension, sedation, or extrapyramidal symptoms. In addition, olanzapine is associated with a possible risk of QT prolongation and should be used cautiously with CYP1A2 and CYP2D6 inhibitors such as duloxetine.
    Fluphenazine: (Moderate) Caution is advisable during concurrent use of fluphenazine and serotonin norepinephrine reuptake inhibitors (SNRIs) since elevations in plasma concentrations of fluphenazine may occur. Phenothiazines are CYP2D6 substrates and duloxetine is a CYP2D6 inhibitor. In addition, fluphenazine is associated with a possible risk of QT prolongation; therefore, cardiac effects are possible.
    Flurbiprofen: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Fluvoxamine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine, desvenlafaxine, duloxetine, and milnacipran. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. In addition, when fluvoxamine, a potent CYP1A2 inhibitor, was coadministered with duloxetine to male subjects (n=14) the duloxetine AUC was increased approximately 6-fold, the Cmax was increased about 2.5-fold, and duloxetine half-life was increased approximately 3-fold. The increased duloxetine exposure induced by fluvoxamine would potentially increase the risk of serotonin-related adverse effects; therefore, the manufacturer recommends avoiding concurrent use of these agents.
    Fosinopril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Gefitinib: (Major) Monitor for an increased incidence of gefitinib-related adverse effects if gefitinib and duloxetine are used concomitantly. Gefitinib is metabolized significantly by CYP3A4 and to a lesser extent by CYP2D6; duloxetine is a CYP2D6 inhibitor. Coadministration may decrease the metabolism of gefitinib and increase gefitinib concentrations. While the manufacturer has provided no guidance regarding the use of gefitinib with CYP2D6 inhibitors, in patients with poor CYP2D6 metabolism, the mean exposure to gefitinib was 2-fold higher when compared to extensive metabolizers; the contribution of drugs that inhibit CYP2D6 on gefitinib exposure has not been evaluated.
    Granisetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering granisetron with other drugs that have serotonergic properties such as duloxetine. If serotonin syndrome is suspected, discontinue granisetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Guaifenesin; Hydrocodone: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Guaifenesin; Hydrocodone; Pseudoephedrine: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Guanabenz: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Guanfacine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Haloperidol: (Moderate) Duloxetine is a moderate inhibitor of CYP2D6. Substantial increases in concentrations of antipsychotics primarily metabolized via CYP2D6, such as haloperidol may also occur. Haloperidol is associated with a possible risk of QT prolongation and should be used cautiously with CYP2D6 inhibitors such as duloxetine.
    Homatropine; Hydrocodone: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Hydralazine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydralazine; Hydrochlorothiazide, HCTZ: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydralazine; Isosorbide Dinitrate, ISDN: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydrochlorothiazide, HCTZ; Irbesartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydrochlorothiazide, HCTZ; Lisinopril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydrochlorothiazide, HCTZ; Losartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydrochlorothiazide, HCTZ; Methyldopa: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydrochlorothiazide, HCTZ; Metoprolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of metoprolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydrochlorothiazide, HCTZ; Olmesartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydrochlorothiazide, HCTZ; Propranolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of propranolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Hydrochlorothiazide, HCTZ; Quinapril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydrochlorothiazide, HCTZ; Telmisartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydrochlorothiazide, HCTZ; Valsartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Hydrocodone: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Hydrocodone; Ibuprofen: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs. (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Hydrocodone; Phenylephrine: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Hydrocodone; Potassium Guaiacolsulfonate: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Hydrocodone; Potassium Guaiacolsulfonate; Pseudoephedrine: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Hydrocodone; Pseudoephedrine: (Minor) The metabolism of hydrocodone to its active metabolite, hydromorphone, is dependent on CYP2D6. Theoretically, coadministration of hydrocodone and a CYP2D6 inhibitor, such as duloxetine, may result in a reduction in the analgesic effect of hydrocodone.
    Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Severe) Concurrent use of methylene blue and serotonin norepinephrine reuptake inhibitors (SNRIs) (e.g., venlafaxine, duloxetine, desvenlafaxine, milnacipran) should generally be avoided due to the potential for serotonin syndrome. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with serotonergic agents such as SNRIs may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent in parathyroid surgery, in patients receiving selective serotonin reuptake inhibitors, SNRIs, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with intravenous methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case report suggests that serotonin toxicity may have occurred post-operatively following administration of standard infusions of methylene blue in a patient receiving duloxetine. The patient experienced disorientation, a mildly elevated temperature, tachycardia, elevated blood pressure, mild agitation, and nystagmus. In a separate case, a patient who had been receiving venlafaxine developed expressive aphasia, confusion, and disinhibition following a methylene blue infusion. The authors concluded that methylene blue toxicity had occurred; however, they did not exclude the possibility of a drug interaction based upon previous reports of an interaction between injectable methylene blue and selective serotonin reuptake inhibitors (SSRIs). Published interaction reports between intravenously administered methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and/or coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. If emergent treatment with methylene blue is required in a patient receiving an SNRI, the SNRI must be stopped immediately and the patient should be monitored for symptoms of CNS toxicity for two weeks or until 24 hours after the last dose of methylene blue, whichever comes first. During non-emergent use of methylene blue, the SNRI should be stopped at least 2 weeks prior to methylene blue treatment, but also taking into consideration the half-life of the SNRI being discontinued. (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Ibuprofen: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Ibuprofen; Oxycodone: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Ibuprofen; Pseudoephedrine: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Iloperidone: (Moderate) Duloxetine is a moderate inhibitor of CYP2D6 and may decrease the clearance of atypical antipsychotics that are CYP2D6 substrates including iloperidone. Decreased metabolism of iloperidone may lead to clinically important adverse reactions that are associated with antipsychotic use, such as extrapyramidal symptoms. In addition, iloperidone is associated with a risk for QT prolongation and torsade de pointes (TdP) and should be used cautiously with CYP2D6 inhibitors such as duloxetine.
    Iloprost: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Imipramine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Clinicians should also be alert for pharmacokinetic interactions between tricyclic antidepressants and SNRIs. Duloxetine and venlafaxine are inhibitors of CYP2D6, and many TCAs are metabolized by this isozyme. Duloxetine increased the maximum plasma concentration (Cmax) of desipramine 1.7-fold and the AUC 2.9-fold in one study. One case report documented a first-time seizure in a patient receiving venlafaxine and trimipramine at therapeutic dosages. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or other adverse effects. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Indomethacin: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Irbesartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Isoniazid, INH: (Major) Due to the risk of serotonin syndrome, concurrent use of duloxetine and medications with MAO-like activity, such as isoniazid, INH, should be avoided if possible. Isoniazid is chemically related to iproniazid, a drug that was known to possess MAO inhibiting activity. Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO and may possess enough MAO inhibiting activity to produce clinical symptoms consistent with serotonergic excess when combined with serotonin norepinephrine reuptake inhibitors. 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. If serotonin syndrome is suspected, duloxetine and concurrent serotonergic agents should be discontinued.
    Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Major) Due to the risk of serotonin syndrome, concurrent use of duloxetine and medications with MAO-like activity, such as isoniazid, INH, should be avoided if possible. Isoniazid is chemically related to iproniazid, a drug that was known to possess MAO inhibiting activity. Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO and may possess enough MAO inhibiting activity to produce clinical symptoms consistent with serotonergic excess when combined with serotonin norepinephrine reuptake inhibitors. 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. If serotonin syndrome is suspected, duloxetine and concurrent serotonergic agents should be discontinued.
    Isoniazid, INH; Rifampin: (Major) Due to the risk of serotonin syndrome, concurrent use of duloxetine and medications with MAO-like activity, such as isoniazid, INH, should be avoided if possible. Isoniazid is chemically related to iproniazid, a drug that was known to possess MAO inhibiting activity. Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO and may possess enough MAO inhibiting activity to produce clinical symptoms consistent with serotonergic excess when combined with serotonin norepinephrine reuptake inhibitors. 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. If serotonin syndrome is suspected, duloxetine and concurrent serotonergic agents should be discontinued.
    Isradipine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Kava Kava, Piper methysticum: (Moderate) The German Commission E and other groups warn that any substances that act on the CNS, including psychopharmacologic agents like venlafaxine, may interact with the phytomedicinal kava kava. This interactions are probably pharmacodynamic in nature, or result from additive mechanisms of action.
    Ketoprofen: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Ketorolac: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Labetalol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of labetalol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Lansoprazole; Naproxen: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Levomilnacipran: (Severe) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, serotonin norepinephrine reuptake inhibitors (SNRIs) such as levomilnacipran and duloxetine should not be coadministered. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SNRI to another SNRI.
    Linezolid: (Severe) The use of linezolid with serotonin norepinephrine reuptake inhibitors (SNRIs) such as duloxetine is contraindicated due to the potential for serotonin syndrome. Linezolid is an antibiotic that also possesses weak non-selective MAO-inhibiting activity which could have additive effects with SNRIs on central serotonin activity. 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. In a patient who requires urgent treatment of a psychiatric condition, interventions other than an SNRI, including hospitalization, should be considered. In some cases, a patient already receiving duloxetine may require urgent treatment with linezolid. If acceptable alternatives to linezolid are not available and the potential benefits of linezolid are determined to outweigh the risks of serotonin syndrome in an individual patient, duloxetine should be stopped promptly, and linezolid can be administered. The patient should be monitored for symptoms of serotonin syndrome for 5 days or until 24 hours after the last dose of linezolid, whichever comes first. Therapy with duloxetine may be resumed 24 hours after the last dose of linezolid.
    Lisdexamfetamine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as lisdexamfetamine. 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. In addition, the MAOI activity of amphetamines may be of concern with the use of drugs that have serotonergic activity. A man developed marked agitation, anxiety, diaphoresis, shivering, tachycardia, tremor, generalized hypertonia, hyperreflexia, 1 to 2 beats of inducible ankle clonus, frequent myoclonic jerking, and tonic spasm of the right side of his orbicularis oris muscle while taking dexamphetamine and venlafaxine. Cessation of both drugs and administration of cyproheptadine led to a stepwise heart rate reduction and complete symptom resolution. Patients receiving SNRIs and amphetamines should be monitored for the emergence of serotonin syndrome, particularly during treatment initiation and during dosage increases. The SNRI and amphetamine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Lisinopril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Lithium: (Major) Lithium is an effective augmenting agent to antidepressants in treatment-resistant depression; however, lithium has been reported to have central serotonin-enhancing effects and may interact pharmacodynamically with duloxetine to cause 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. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and lithium should be discontinued and symptomatic treatment should be initiated. One systematic review and meta-analysis of lithium augmentation of tricyclic and second generation antidepressants in major depression found no difference in discontinuation rate due to adverse events between the lithium and placebo groups. However, some data indicate that the elderly may have increased susceptibility to neurotoxicity (e.g., fine tremor, ataxia, severe memory impairment, and/or gait disturbances) from concurrent use of lithium and antidepressants, despite therapeutic lithium concentrations.
    Loperamide: (Moderate) The plasma concentration of loperamide, a CYP2D6 substrate, may be increased when administered concurrently with duloxetine, a CYP2D6 inhibitor. If these drugs are used together, monitor for loperamide-associated adverse reactions, such as CNS effects and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest).
    Loperamide; Simethicone: (Moderate) The plasma concentration of loperamide, a CYP2D6 substrate, may be increased when administered concurrently with duloxetine, a CYP2D6 inhibitor. If these drugs are used together, monitor for loperamide-associated adverse reactions, such as CNS effects and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest).
    Lorcaserin: (Major) Based on the mechanism of action of lorcaserin and the theoretical potential for serotonin syndrome, use with extreme caution in combination with other drugs that may affect the serotonergic neurotransmitter systems, including, serotonin norepinephrine reuptake inhibitors. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or Neuroleptic Malignant Syndrome (NMS) like signs and symptoms.
    Losartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Macitentan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Magnesium Salicylate: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Maprotiline: (Major) Documentation is not available on the concurrent use of duloxetine with many CNS agents. Caution should be observed when administering duloxetine with other CNS-active drugs in the absence of clinical data regarding combined use. Examples of these drugs include the maprotiline. In addition, duloxetine is a moderate inhibitor of CYP2D6, and maprotiline appears to be metabolized by this isozyme. It is possible that duloxetine could increase the risk of cyclic-antidepressant-induced side effects or toxicity.
    Meclofenamate Sodium: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Mefenamic Acid: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Meloxicam: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Meperidine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as meperidine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Meperidine; Promethazine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as meperidine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Mesoridazine: (Major) Mesoridazine has an established risk of QT prolongation and torsade de pointes (TdP). Agents that reduce mesoridazine metabolism, like duloxetine, may increase the risk for adverse cardiac events. Phenothiazines are CYP2D6 substrates, and duloxetine is a moderate CYP2D6 inhibitor.
    Methamphetamine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as amphetamines. 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. In addition, the MAOI activity of amphetamines may be of concern with the use of drugs that have serotonergic activity. A man developed marked agitation, anxiety, diaphoresis, shivering, tachycardia, tremor, generalized hypertonia, hyperreflexia, 1 to 2 beats of inducible ankle clonus, frequent myoclonic jerking, and tonic spasm of the right side of his orbicularis oris muscle while taking dexamphetamine and venlafaxine. Cessation of both drugs and administration of cyproheptadine led to a stepwise heart rate reduction and complete symptom resolution. Patients receiving an SNRI and an amphetamine should be monitored for the emergence of serotonin syndrome, particularly during treatment initiation and during dosage increases. The SNRI and amphetamine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Severe) Concurrent use of methylene blue and serotonin norepinephrine reuptake inhibitors (SNRIs) (e.g., venlafaxine, duloxetine, desvenlafaxine, milnacipran) should generally be avoided due to the potential for serotonin syndrome. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with serotonergic agents such as SNRIs may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent in parathyroid surgery, in patients receiving selective serotonin reuptake inhibitors, SNRIs, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with intravenous methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case report suggests that serotonin toxicity may have occurred post-operatively following administration of standard infusions of methylene blue in a patient receiving duloxetine. The patient experienced disorientation, a mildly elevated temperature, tachycardia, elevated blood pressure, mild agitation, and nystagmus. In a separate case, a patient who had been receiving venlafaxine developed expressive aphasia, confusion, and disinhibition following a methylene blue infusion. The authors concluded that methylene blue toxicity had occurred; however, they did not exclude the possibility of a drug interaction based upon previous reports of an interaction between injectable methylene blue and selective serotonin reuptake inhibitors (SSRIs). Published interaction reports between intravenously administered methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and/or coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. If emergent treatment with methylene blue is required in a patient receiving an SNRI, the SNRI must be stopped immediately and the patient should be monitored for symptoms of CNS toxicity for two weeks or until 24 hours after the last dose of methylene blue, whichever comes first. During non-emergent use of methylene blue, the SNRI should be stopped at least 2 weeks prior to methylene blue treatment, but also taking into consideration the half-life of the SNRI being discontinued.
    Methyldopa: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Methylene Blue: (Severe) Concurrent use of methylene blue and serotonin norepinephrine reuptake inhibitors (SNRIs) (e.g., venlafaxine, duloxetine, desvenlafaxine, milnacipran) should generally be avoided due to the potential for serotonin syndrome. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with serotonergic agents such as SNRIs may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent in parathyroid surgery, in patients receiving selective serotonin reuptake inhibitors, SNRIs, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with intravenous methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case report suggests that serotonin toxicity may have occurred post-operatively following administration of standard infusions of methylene blue in a patient receiving duloxetine. The patient experienced disorientation, a mildly elevated temperature, tachycardia, elevated blood pressure, mild agitation, and nystagmus. In a separate case, a patient who had been receiving venlafaxine developed expressive aphasia, confusion, and disinhibition following a methylene blue infusion. The authors concluded that methylene blue toxicity had occurred; however, they did not exclude the possibility of a drug interaction based upon previous reports of an interaction between injectable methylene blue and selective serotonin reuptake inhibitors (SSRIs). Published interaction reports between intravenously administered methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and/or coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. If emergent treatment with methylene blue is required in a patient receiving an SNRI, the SNRI must be stopped immediately and the patient should be monitored for symptoms of CNS toxicity for two weeks or until 24 hours after the last dose of methylene blue, whichever comes first. During non-emergent use of methylene blue, the SNRI should be stopped at least 2 weeks prior to methylene blue treatment, but also taking into consideration the half-life of the SNRI being discontinued.
    Methylphenidate: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when coadministering drugs that have serotonergic properties such as methylphenidate and serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome has been reported during concurrent use of other serotonergic antidepressants (i.e., SSRIs) and methylphenidate. There is also a case of a neuroleptic malignant syndrome-like reaction occurring in a child on chronic methylphenidate therapy 45 minutes after ingesting a dose of venlafaxine. It is unclear if the reaction was the result of a drug interaction. 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. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. If serotonin syndrome occurs, all serotonergic agents should be discontinued and appropriate medical management should be implemented.
    Metoclopramide: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that are dopamine antagonists such as metoclopramide. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. In addition, metoclopramide may cause extrapyramidal reactions (e.g., acute dystonic reactions, pseudo-parkinsonism, akathisia, or tardive dyskinesia) and is contraindicated with other drugs that are likely to cause extrapyramidal effects. Dystonia, akathisia, trismus, torticollis, dyskinesia, tardive dyskinesia, pseudo-parkinsonism, and/or extrapyramidal disorder (unspecified) have been reported during use of SNRIs; however, these effects appear uncommon. Patients receiving concurrent treatment with dopamine antagonists may be more predisposed to these reactions. Case reports documenting an interaction between metoclopramide and other serotonergic agents (i.e., SSRIs) suggest that serotonin syndrome and/or movement disorders are possible during combined use of metoclopramide and SNRIs. Patients receiving SNRIs and metoclopramide should be monitored for the emergence of serotonin syndrome, neuroleptic malignant syndrome-like reactions, or other adverse effects.
    Metoprolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of metoprolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Milnacipran: (Severe) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, serotonin norepinephrine reuptake inhibitors (SNRIs) including venlafaxine, desvenlafaxine, duloxetine, levomilnacipran, and milnacipran should not be coadministered. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SNRI to another SNRI.
    Minoxidil: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Mirabegron: (Moderate) Mirabegron is a moderate CYP2D6 inhibitor. Exposure of drugs metabolized by CYP2D6 isoenzymes such as duloxetine may be increased when co-administered with mirabegron. Therefore, appropriate monitoring and dose adjustment may be necessary.
    Mirtazapine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when coadministering drugs that have serotonergic properties such as mirtazapine and duloxetine. Cases of serotonin syndrome have been reported between mirtazapine and other antidepressants such as selective serotonin reuptake inhibitors (SSRIs). 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. If serotonin syndrome occurs, serotonergic agents should be discontinued and appropriate medical treatment should be implemented.
    Moexipril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Monoamine oxidase inhibitors: (Severe) Due to the risk of serotonin syndrome, monoamine oxidase inhibitors (MAOIs) intended to treat psychiatric disorders are contraindicated for use with serotonin norepinephrine reuptake inhibitors (SNRIs). MAOIs should not be used within 5 days of discontinuing treatment with duloxetine or within 7 days of discontinuing treatment with other SNRIs. Conversely, SNRIs should not be initiated within 14 days of stopping an MAOI. 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. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome.
    Morphine: (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.
    Morphine; Naltrexone: (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.
    Nabumetone: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Nadolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of nadolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Naproxen: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Naproxen; Pseudoephedrine: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Naproxen; Sumatriptan: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Nebivolol: (Moderate) Monitor for increased toxicity as well as increased therapeutic effect of nebivolol if coadministered with duloxetine. Nebivolol is metabolized by CYP2D6. Although data are lacking, CYP2D6 inhibitors, such as duloxetine, could potentially increase nebivolol plasma concentrations via CYP2D6 inhibition; the clinical significance of this potential interaction is unknown, but an increase in adverse effects is possible. In addition, orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of nebivolol and duloxetine may increase the risk of hypotension.
    Nebivolol; Valsartan: (Moderate) Monitor for increased toxicity as well as increased therapeutic effect of nebivolol if coadministered with duloxetine. Nebivolol is metabolized by CYP2D6. Although data are lacking, CYP2D6 inhibitors, such as duloxetine, could potentially increase nebivolol plasma concentrations via CYP2D6 inhibition; the clinical significance of this potential interaction is unknown, but an increase in adverse effects is possible. In addition, orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of nebivolol and duloxetine may increase the risk of hypotension. (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Nefazodone: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as nefazodone. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Netupitant; Palonosetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering palonosetron with other drugs that have serotonergic properties such as duloxetine. If serotonin syndrome is suspected, discontinue palonosetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Nicardipine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Nifedipine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Nimodipine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Nisoldipine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Nitroglycerin: (Minor) Nitroglycerin can cause hypotension. This action may be additive with other agents that can cause hypotension such as antidepressants. Patients should be monitored more closely for hypotension if nitroglycerin is used concurrently with antidepressants.
    Nitroprusside: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Nonsteroidal antiinflammatory drugs: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Nortriptyline: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Clinicians should also be alert for pharmacokinetic interactions between tricyclic antidepressants and SNRIs. Duloxetine and venlafaxine are inhibitors of CYP2D6, and many TCAs are metabolized by this isozyme. Duloxetine increased the maximum plasma concentration (Cmax) of desipramine 1.7-fold and the AUC 2.9-fold in one study. One case report documented a first-time seizure in a patient receiving venlafaxine and trimipramine at therapeutic dosages. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or other adverse effects. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Olanzapine: (Moderate) Duloxetine is an inhibitor of CYP1A2 and CYP2D6 and should be used cautiously with atypical antipsychotics metabolized by CYP1A2 and CYP2D6 such as olanzapine. Plasma concentrations of atypical antipsychotics primarily metabolized via CYP1A2, such as olanzapine, may increase substantially during concurrent use. Decreased metabolism of olanzapine may lead to clinically important adverse reactions, such as orthostatic hypotension, sedation, or extrapyramidal symptoms. In addition, olanzapine is associated with a possible risk of QT prolongation and should be used cautiously with CYP1A2 and CYP2D6 inhibitors such as duloxetine.
    Olmesartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Ondansetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering ondansetron with other drugs that have serotonergic properties such as duloxetine. If serotonin syndrome is suspected, discontinue ondansetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Oritavancin: (Moderate) Duloxetine is metabolized by CYP2D6; oritavancin is a weak CYP2D6 inducer. Plasma concentrations and efficacy of duloxetine may be reduced if these drugs are administered concurrently.
    Oxaprozin: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Paliperidone: (Moderate) Duloxetine is a moderate inhibitor of CYP2D6 and may decrease the clearance of CYP2D6 substrates including paliperidone. Decreased metabolism of paliperidone may lead to clinically important adverse reactions, such as extrapyramidal symptoms. In addition, paliperidone is associated with a risk for QT prolongation and torsade de pointes (TdP) and should be used cautiously with CYP2D6 inhibitors such as duloxetine.
    Palonosetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering palonosetron with other drugs that have serotonergic properties such as duloxetine. If serotonin syndrome is suspected, discontinue palonosetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Paroxetine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine, desvenlafaxine, duloxetine, and milnacipran. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome.
    Peginterferon Alfa-2b: (Moderate) Monitor for adverse effects associated with increased exposure to duloxetine if peginterferon alfa-2b is coadministered. Peginterferon alfa-2b is a CYP1A2 and CYP2D6 inhibitor, while duloxetine is a CYP1A2 and CYP2D6 substrate.
    Penbutolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of penbutolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Pentazocine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as pentazocine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Pentazocine; Naloxone: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as pentazocine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Perindopril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Perindopril; Amlodipine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Perphenazine: (Moderate) Caution is advisable during concurrent use of perphenazine and serotonin norepinephrine reuptake inhibitors (SNRIs) since elevations in plasma concentrations of perphenazine may occur. Phenothiazines are CYP2D6 substrates, and SNRIs including duloxetine are CYP2D6 inhibitors. In addition, perphenazine is associated with a possible risk of QT prolongation; therefore, cardiac effects are possible.
    Perphenazine; Amitriptyline: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Clinicians should also be alert for pharmacokinetic interactions between tricyclic antidepressants and SNRIs. Duloxetine and venlafaxine are inhibitors of CYP2D6, and many TCAs are metabolized by this isozyme. Duloxetine increased the maximum plasma concentration (Cmax) of desipramine 1.7-fold and the AUC 2.9-fold in one study. One case report documented a first-time seizure in a patient receiving venlafaxine and trimipramine at therapeutic dosages. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or other adverse effects. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated. (Moderate) Caution is advisable during concurrent use of perphenazine and serotonin norepinephrine reuptake inhibitors (SNRIs) since elevations in plasma concentrations of perphenazine may occur. Phenothiazines are CYP2D6 substrates, and SNRIs including duloxetine are CYP2D6 inhibitors. In addition, perphenazine is associated with a possible risk of QT prolongation; therefore, cardiac effects are possible.
    Phenoxybenzamine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Phentermine: (Moderate) Use phentermine and selective serotonin reuptake inhibitors (SSRIs) or serotonin norepinephrine reuptake inhibitors (SNRIs) together with caution; use together may be safe and efficacious for some patients based on available data, provided the patient is on a stable antidepressant regimen and receives close clinical monitoring. Regular appointments to assess the efficacy of the weight loss treatment, the emergence of adverse events, and blood pressure monitoring are recommended. Watch for excessive serotonergic effects. Phentermine is related to the amphetamines, and there has been historical concern that phentermine might exhibit potential to cause serotonin syndrome or cardiovascular or pulmonary effects when combined with serotonergic agents. One case report describes adverse reactions with phentermine and fluoxetine. However, recent data suggest that phentermine's effect on MAO inhibition and serotonin augmentation is minimal at therapeutic doses, and that phentermine does not additionally increase plasma serotonin levels when combined with other serotonergic agents. In large controlled clinical studies, patients were allowed to start therapy with phentermine or phentermine; topiramate extended-release for obesity along with their antidepressants (e.g., SSRIs or SNRIs, but not MAOIs or TCAs) as long as the antidepressant dose had been stable for at least 3 months prior to the initiation of phentermine, and the patient did not have suicidal ideation or more than 1 episode of major depression documented. In analyses of the results, therapy was generally well tolerated, especially at lower phentermine doses, based on discontinuation rates and reported adverse events. Because depression and obesity often coexist, the study data may be important to providing optimal therapies.
    Phentermine; Topiramate: (Moderate) Use phentermine and selective serotonin reuptake inhibitors (SSRIs) or serotonin norepinephrine reuptake inhibitors (SNRIs) together with caution; use together may be safe and efficacious for some patients based on available data, provided the patient is on a stable antidepressant regimen and receives close clinical monitoring. Regular appointments to assess the efficacy of the weight loss treatment, the emergence of adverse events, and blood pressure monitoring are recommended. Watch for excessive serotonergic effects. Phentermine is related to the amphetamines, and there has been historical concern that phentermine might exhibit potential to cause serotonin syndrome or cardiovascular or pulmonary effects when combined with serotonergic agents. One case report describes adverse reactions with phentermine and fluoxetine. However, recent data suggest that phentermine's effect on MAO inhibition and serotonin augmentation is minimal at therapeutic doses, and that phentermine does not additionally increase plasma serotonin levels when combined with other serotonergic agents. In large controlled clinical studies, patients were allowed to start therapy with phentermine or phentermine; topiramate extended-release for obesity along with their antidepressants (e.g., SSRIs or SNRIs, but not MAOIs or TCAs) as long as the antidepressant dose had been stable for at least 3 months prior to the initiation of phentermine, and the patient did not have suicidal ideation or more than 1 episode of major depression documented. In analyses of the results, therapy was generally well tolerated, especially at lower phentermine doses, based on discontinuation rates and reported adverse events. Because depression and obesity often coexist, the study data may be important to providing optimal therapies.
    Phentolamine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Pimozide: (Major) Although not specifically contraindicated by either manufacturer, duloxetine and pimozide co-administration should be avoided if possible. Duloxetine is a moderate inhibitor of CYP2D6, and pimozide is a CYP2D6 substrate with an established risk of QT prolongation and torsade de pointes (TdP). Although CYP3A4 is the primary elimination pathway of pimozide, most antidepressants with CYP2D6 inhibitory effects are contraindicatd for use with pimozide by the manufacturers due to the potential severity of the interaction.
    Pindolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of pindolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Piroxicam: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Prasugrel: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors (e.g., cilostazol, clopidogrel, dipyridamole, ticlopidine, platelet glycoprotein IIb/IIIa inhibitors). Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Prazosin: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Procarbazine: (Major) Concurrent use of procarbazine and serotonin norepinephrine reuptake inhibitors (SNRIs) should be avoided if possible. Procarbazine is a weak monoamine oxidase inhibitor (MAOI). Since monoamine oxidase type A deaminates serotonin, administration of a non-selective MAO inhibitor concurrently with an SNRI can lead to serious reactions including serotonin syndrome or neuroleptic malignant syndrome-like reactions. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. If combination therapy is necessary, patients should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Prochlorperazine: (Moderate) Caution is advisable during concurrent use of prochlorperazine and serotonin norepinephrine reuptake inhibitors (SNRIs) since elevations in plasma concentrations of prochlorperazine may occur. Phenothiazines are CYP2D6 substrates, and SNRIs including duloxetine are CYP2D6 inhibitors.
    Propranolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of propranolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Protriptyline: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Clinicians should also be alert for pharmacokinetic interactions between tricyclic antidepressants and SNRIs. Duloxetine and venlafaxine are inhibitors of CYP2D6, and many TCAs are metabolized by this isozyme. Duloxetine increased the maximum plasma concentration (Cmax) of desipramine 1.7-fold and the AUC 2.9-fold in one study. One case report documented a first-time seizure in a patient receiving venlafaxine and trimipramine at therapeutic dosages. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or other adverse effects. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Quetiapine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with drugs that are dopamine antagonists such as quetiapine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving quetiapine and an SNRI should be monitored for the emergence of serotonin syndrome, neuroleptic malignant syndrome-like reactions, or other adverse effects.
    Quinapril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Ramipril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Ranolazine: (Moderate) Ranolazine is metabolized mainly by CYP3A and to a lesser extent by CYP2D6. Metoclopramide is a known CYP2D6 inhibitor; coadministration with ranolazine may result in increased plasma concentrations of ranolazine. The manufacturer specifies that no dosage adjustment of ranolazine is necessary when coadministering CYP2D6 inhibitors. Until further data are available, it is prudent to cautiously monitor the concurrent use of ranolazine and significant CYP2D6 inhibitors since potential increases in plasma concentrations of ranolazine may result in adverse effects.
    Rasagiline: (Major) It is recommended to avoid concurrent use of rasagiline and antidepressants, including serotonin norepinephrine reuptake inhibitors (SNRIs). Severe CNS toxicity with hyperpyrexia has been reported during concurrent use of antidepressants and selective or non-selective MAOIs. During post-marketing use of rasagiline, non-fatal cases of serotonin syndrome have been reported during concomitant antidepressant administration. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. At least 2 weeks should elapse between stopping rasagiline treatment and beginning therapy with any antidepressant. Conversely, when discontinuing the antidepressant, it is advisable to wait the length of 4 to 5 half lives of the individual agent being discontinued prior to initiation with rasagiline.
    Remifentanil: (Moderate) Concurrent use of remifentanil with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. If concurrent use is necessary, closely monitor the patient, particularly during remifentanil initiation and dosage adjustment. Discontinue remifentanil if serotonin syndrome is suspected.
    Reserpine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Reteplase, r-PA: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Riociguat: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Rofecoxib: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Rolapitant: (Major) Use caution if duloxetine and rolapitant are used concurrently, and monitor for duloxetine-related adverse effects. Duloxetine is a CYP2D6 substrate and rolapitant is a moderate CYP2D6 inhibitor; the inhibitory effect of rolapitant lasts for at least 7 days, and may last longer after single dose administration. The Cmax and AUC of another CYP2D6 substrate, dextromethorphan, were increased by 120% and 160%, respectively, on day 1 with rolapitant, and by 180% and 230%, respectively, on day 8 after rolapitant administration.
    Sacubitril; Valsartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Safinamide: (Severe) Safinamide is contraindicated for use with serotonin norepinephrine reuptake inhibitors (SNRIs) 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 an SNRI.
    Salicylates: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Salsalate: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Selexipag: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Serotonin-Receptor Agonists: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering a selective serotonin norepinephrine reuptake inhibitor (SNRI) like duloxetine with other drugs that have serotonergic properties such as serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan) because of the potential risk and severity of serotonin syndrome. Serotonin syndrome has been reported during concurrent use of drugs from these drug classes. Some patients had used the combination previously without incident when serotonin syndrome occurred. Some cases have involved hospitalization. Serotonin syndrome consists of symptoms such as mental status changes (e.g., agitation, confusion, hallucinations), diaphoresis, hyperreflexia, hypertension, diarrhea, fever, tremor, and, in some instances, respiratory failure. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring for serotonin syndrome is recommended if combination therapy with is required. Risk factors can include a recent dose increase of the SNRI or the addition of other serotonergic medications to an existing SNRI regimen.
    Sertraline: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine, desvenlafaxine, duloxetine, and milnacipran. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome.
    Sibutramine: (Major) Sibutramine is a serotonin reuptake inhibitor. Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering sibutramine with other drugs that have serotonergic properties such as serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving sibutramine in combination with an SNRI should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Sildenafil: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    St. John's Wort, Hypericum perforatum: (Major) Due to possible additive effects on serotonin concentrations, it is advisable to avoid combinations of St. John's wort, Hypericum perforatum with serotonin norepinephrine reuptake inhibitors (SNRIs). Interactions between SNRIs and serotonergic agents can lead to serious reactions including serotonin syndrome or neuroleptic malignant syndrome-like reactions. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome.
    Streptokinase: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Sulindac: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Tacrine: (Moderate) Co-administration of duloxetine and potent inhibitors of CYP1A2 should be avoided. Duloxetine is partially metabolized by CYP1A2. One study involving a potent CYP1A2 inhibitor in concomitant use with duloxetine showed that duloxetine exposure was significantly increased. Concurrent use of duloxetine and tacrine, a CYP1A2 inhibitor, may result in excessive serotonin activity. Careful monitoring is recommended if concurrent therapy is considered necessary.
    Tadalafil: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Tamoxifen: (Major) Tamoxifen, a selective estrogen receptor modulator (SERM), is converted to endoxifen and other active metabolites by cytochrome P450 (CYP) enzymes (e.g., 2D6, 3A4). Several antidepressants are often prescribed to alleviate tamoxifen-associated hot flashes. Many antidepressants are CYP2D6 inhibitors and may reduce plasma endoxifen concentrations. A trial of 1298 patients with breast cancer compared the rate of breast cancer recurrence in patients treated with tamoxifen with or without a CYP2D6 inhibitor. Patients who received tamoxifen in combination with a CYP2D6 inhibitor had a significantly higher rate of breast cancer recurrence at 2 years (13.9% v. 7.5%, p < 0.001). In a retrospective population-based cohort study, 2430 women with breast cancer were identified to have received tamoxifen concomitantly with an SSRI antidepressant. Patients who received paroxetine (n = 630) had a significant increase in the risk of death from breast cancer. No increased risk of breast cancer mortality was observed in patients receiving citalopram, fluoxetine, fluvoxamine, sertraline, or venlafaxine. A separate observational study of 1990 patients assessed event free time with adjuvant tamoxifen treatment for breast cancer; only 215 of these patients were administered a CYP2D6 inhibitor, however no clinically significant differences were observed with the addition of a CYP2D6 inhibitor. Paroxetine, fluoxetine, fluvoxamine, bupropion, and duloxetine are considered moderate to potent inhibitors of CYP2D6. If treatment with an antidepressant and tamoxifen is necessary, it may be preferable to use an agent with less potent or no inhibition of CYP2D6. Sertraline, citalopram, venlafaxine, and escitalopram are considered mild inhibitors, and may be preferable choices. Further, in an analysis of CYP2D6 inhibitors, the following order of inhibitory potency was observed (in descending order): paroxetine, fluoxetine, sertraline, citalopram and venlafaxine.
    Tamsulosin: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as duloxetine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
    Tapentadol: (Major) Caution is advised when tapentadol is coadministered with serotonin norepinephrine reuptake inhibitors as this combination may result in excessive concentrations of serotonin and/or norepinephrine and increase the potential for adverse cardiac events and serotonin syndrome development. If concomitant treatment is clinically warranted, careful observation of the patient is advised, especially during initiation of the second therapy and after dosage adjustments (increases) of either agent.
    Tedizolid: (Minor) Use caution with the concurrent use of tedizolid and serotonin norepinephrine reuptake inhibitors (SNRIs) due to the theoretical risk of serotonin sydrome. Animal studies did not predict serotonergic effects; however, patients on concurrent SNRIs were excluded from clinical trials. Additionally, tedizolid is an antibiotic that is also a weak reversible, non-selective MAO inhibitor and monoamine oxidase type A deaminates serotonin; therefore, coadministration theoretically could lead to serious reactions including serotonin syndrome. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Telmisartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Tenecteplase, TNK-tPA: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Terazosin: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Teriflunomide: (Moderate) Use caution when administering teriflunomide and duloxetine concurrently. In vivo data suggest that teriflunomide is a weak inducer of CYP1A2. Coadministration of teriflunomide with CYP1A2 substrates, such as duloxetine, may decrease duloxetine exposure and lead to a reduction in efficacy.
    Theophylline, Aminophylline: (Moderate) Close monitoring of theophylline levels is advisable during concurrent use of duloxetine and theophylline. Theophylline is a substrate for CYP1A2 and duloxetine is a CYP1A2 inhibitor. In two clinical studies, the average increase in the theophylline AUC was 7% (range: 1%-15%) and 20% (range: 13%-27%) when co-administered with duloxetine.
    Thiethylperazine: (Moderate) Duloxetine is an inhibitor of CYP2D6, and concurrent use with CYP2D6 substrates, such as the phenothiazines, may result in increased plasma concentrations, and potential increased risk for phenothiazine-related side effects.
    Thioridazine: (Severe) Duloxetine is a moderate inhibitor of CYP2D6 and the use of thioridazine concomitantly with CYP2D6 inhibitors is contraindicated due to the theoretical risk of prolongation of QTc interval and subsequent arrhythmias, or other serious side effects, due to elevated serum concentrations of thioridazine.
    Thrombolytic Agents: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Ticagrelor: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors (e.g., cilostazol, clopidogrel, dipyridamole, ticlopidine, platelet glycoprotein IIb/IIIa inhibitors). Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Ticlopidine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Timolol: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of timolol and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary.
    Tirofiban: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Tolmetin: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Tramadol: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tramadol. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. In one case, the addition of tramadol to extended-release venlafaxine (300 mg/day) and mirtazapine (30 mg/day) likely caused serotonin syndrome. A patient developed agitation, confusion, severe shivering, diaphoresis, myoclonus, hyperreflexia, mydriasis, tachycardia, and fever within 7 weeks of taking tramadol 400 mg daily. He had taken 300 mg tramadol without difficulty. Discontinuation of the 3 drugs and rehydration led to symptom resolution over 36 hours. Reinstitution of the antidepressants 3 days after patient presentation was uneventful. Also, duloxetine may inhibit the formation of the active M1 metabolite of tramadol by inhibiting CYP2D6. The inhibition of this metabolite may decrease the analgesic effectiveness of tramadol but increase the level of the parent compound, which has more serotonergic activity than the metabolite. The risk for serious adverse effects such as seizures and serotonin syndrome may be increased. Patients receiving tramadol in combination with an SNRI should be monitored for the emergence of serotonin syndrome, neuroleptic malignant syndrome-like reactions, or other adverse effects.
    Trandolapril: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Trandolapril; Verapamil: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Trazodone: (Major) Coadministration may increase the risk of serotonin syndrome. Serotonin syndrome has been reported with SNRIs, including duloxetine, both when taken alone, but especially when coadministered with other serotonergic agents. Trazodone blocks the reuptake of serotonin at the presynaptic neuronal membrane. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated. Because psychoactive drugs may have additive CNS effects, be alert for drowsiness or other CNS complaints.
    Treprostinil: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Tricyclic antidepressants: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Clinicians should also be alert for pharmacokinetic interactions between tricyclic antidepressants and SNRIs. Duloxetine and venlafaxine are inhibitors of CYP2D6, and many TCAs are metabolized by this isozyme. Duloxetine increased the maximum plasma concentration (Cmax) of desipramine 1.7-fold and the AUC 2.9-fold in one study. One case report documented a first-time seizure in a patient receiving venlafaxine and trimipramine at therapeutic dosages. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or other adverse effects. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Trifluoperazine: (Moderate) Caution is advisable during concurrent use of trifluoperazine and serotonin norepinephrine reuptake inhibitors (SNRIs) since elevations in plasma concentrations of trifluoperazine may occur. Phenothiazines are CYP2D6 substrates, and SNRIs including duloxetine are CYP2D6 inhibitors.
    Trimipramine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Clinicians should also be alert for pharmacokinetic interactions between tricyclic antidepressants and SNRIs. Duloxetine and venlafaxine are inhibitors of CYP2D6, and many TCAs are metabolized by this isozyme. Duloxetine increased the maximum plasma concentration (Cmax) of desipramine 1.7-fold and the AUC 2.9-fold in one study. One case report documented a first-time seizure in a patient receiving venlafaxine and trimipramine at therapeutic dosages. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or other adverse effects. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, duloxetine and the concomitant serotonergic agent should be discontinued and symptomatic treatment should be initiated.
    Urokinase: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Valdecoxib: (Moderate) Platelet aggregation may be impaired by duloxetine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving Nonsteroidal antiinflammatory drugs (NSAIDs). Mmonitor for signs and symptoms of bleeding when duloxetine is coadministered with NSAIDs.
    Valerian, Valeriana officinalis: (Moderate) The German Commission E and other groups warn that any substances that act on the CNS, including psychopharmacologic agents, may interact with the phytomedicinal valerian, Valeriana officinalis. These interactions are probably pharmacodynamic in nature, or result from additive mechanisms of action.
    Valsartan: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Vemurafenib: (Moderate) Concomitant use of vemurafenib and duloxetine may result in increased duloxetine concentrations. Vemurafenib is a CYP1A2 and CYP2D6 inhibitor and duloxetine is a substrate of these isoenzymes. Monitor the patient for signs of excessive serotonin activity.
    Venlafaxine: (Severe) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, serotonin norepinephrine reuptake inhibitors (SNRIs) including venlafaxine, desvenlafaxine, duloxetine, levomilnacipran, and milnacipran should not be coadministered. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SNRI to another SNRI.
    Verapamil: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
    Vilazodone: (Major) Due to possible additive effects on serotonin concentrations, it is advisable to avoid combining serotonin norepinephrine reuptake inhibitors (SNRIs) with vilazodone. Interactions between vilazodone and serotonergic agents can lead to 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. Patients receiving vilazodone and an SNRI should be monitored for the emergence of serotonin syndrome, particularly during treatment initiation and during dosage increases. Vilazodone and the SNRI should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Vorapaxar: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors (e.g., cilostazol, clopidogrel, dipyridamole, ticlopidine, platelet glycoprotein IIb/IIIa inhibitors). Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Vortioxetine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, vortioxetine should generally not be administered with serotonin norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine, desvenlafaxine, duloxetine, and milnacipran. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. If serotonin syndrome is suspected, vortioxetine and concurrent serotonergic agents should be discontinued.
    Zileuton: (Moderate) Co-administration of duloxetine and potent inhibitors of CYP1A2 should be avoided. Duloxetine is partially metabolized by CYP1A2. One study involving a potent CYP1A2 inhibitor in concomitant use with duloxetine showed that duloxetine exposure was significantly increased. Concurrent use of duloxetine and zileuton, a CYP1A2 inhibitor, may result in excessive serotonin activity. Careful monitoring is recommended if concurrent therapy is considered necessary.
    Zolpidem: (Moderate) Disorientation, delusions, or hallucinations have been reported rarely during co-administration of zolpidem and antidepressants. The duration of the visual hallucinations has ranged from 30 minutes to 7 hours. The interaction is thought to be pharmacodynamic in nature; therefore, a similar reaction is possible with duloxetine. Data from a clinical study in which SSRI-treated patients were given immediate-release zolpidem revealed that four of the seven discontinuations during double-blind treatment with zolpidem (n = 95) were associated with impaired concentration, continuing or aggravated depression, and manic reaction.

    PREGNANCY AND LACTATION

    Pregnancy

    Use caution when duloxetine is administered to a breast-feeding women. Duloxetine, a dual serotonin-norepinephrine reuptake inhibitor, is excreted into the breast milk of lactating women. The estimated daily infant dose is approximately 0.14% of the maternal dose. The disposition of duloxetine was studied in 6 lactating women who were at least 12 weeks postpartum and had elected to wean their infants. The women were given 40 mg of duloxetine twice daily for 3.5 days. The peak concentration measured in breast milk occurred at a median of 3 hours after the dose. The amount of duloxetine in breast milk was approximately 7 mcg/day while on that dose; the estimated daily infant dose was approximately 2 mcg/kg/day. The estimated daily infant dose is approximately 0.14% of the maternal dose. The presence of metabolites in breast milk was not examined. The developmental and health benefits of human milk feeding should be considered along with the mother’s clinical need for duloxetine and any potential adverse effects on the milk-fed infant from the drug or from the underlying maternal condition. A pooled analysis found that maternal use of sertraline, along with nortriptyline and paroxetine, usually produced undetectable or low drug concentrations in infant serum and, therefore, may be the preferred antidepressants in breast-feeding mothers. Consider the benefits of breast-feeding, the risk of potential drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding baby experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.

    MECHANISM OF ACTION

    Duloxetine inhibits the reuptake of both serotonin (5-HT) and norepinephrine (NE). The exact mechanism of its antidepressant effect is not known. The potency of duloxetine to inhibit reuptake is greater for 5-HT than for NE, however, inhibition of the NE reuptake process occurs at a considerably lower dose than for venlafaxine, a similar 5-HT/NE reuptake inhibitor. The ability of duloxetine to affect NE reuptake appears to occur at doses >= 60 mg/day. Duloxetine also inhibits 5-HT uptake in human platelets, and this effect has been associated with potentiation of bleeding in some reports. Similar to the selective serotonin reuptake inhibitors (SSRIs), duloxetine does not exert significant activity at dopaminergic, histaminergic, muscarinic, alpha1-adrenergic receptors, 5-HT1A, 5-HT1B, 5-HT1D, 5-HT2A, 5-HT2C, or opioid receptors in vivo or in vitro. Duloxetine does not inhibit monoamine oxidase (MAO). The major circulating metabolites of duloxetine do not appear to contribute to its pharmacologic activity. In the treatment of stress urinary incontinence, inhibition of 5-HT and NE reuptake by duloxetine increases the activity of the bladder detrusor muscle and the urethral sphincter thereby promoting continence.

    PHARMACOKINETICS

    Duloxetine is administered orally. It is distributed widely throughout the body. The Vd averages 1640 L. Duloxetine is highly protein bound (> 90%); however, plasma protein binding is not affected by renal or hepatic impairment. It undergoes extensive hepatic oxidation to numerous inactive metabolites with only 3% of the parent drug remaining in the plasma. Duloxetine is metabolized by CYP2D6 and CYP1A2, with moderate potential for drug interactions involving CYP2D6. The elimination half-life ranges 9.2—19.1 hours (mean 12.5) with steady state concentrations occurring in about 3 days. Only trace amounts are present in the urine; 70% of the dose appears as metabolites in the urine and 20% is excreted in the feces.
     
    Affected cytochrome P450 isoenzymes: CYP2D6, CYP1A2
    Duloxetine is a moderate inhibitor of CYP2D6 and in vitro and in vivo data indicate it is a CYP1A2 inhibitor.

    Oral Route

    Duloxetine is well absorbed; however, absolute bioavailability is not known due to lack of an intravenous dosage form. There is a median 2-hour lag before absorption begins, with Cmax occurring at 6 hours post dose. Food, while not affecting Cmax, can delay the time to reach peak concentration by 6—10 hours and may decrease the AUC by 10%. Additionally, absorption is delayed by 3 hours and clearance is reduced by one-third if the dose is given in the evening compared to morning; however, it does not appear that duloxetine pharmacodynamics are altered. Steady-state concentrations typically occur after 3 days of dosing.