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  • CLASSES

    Muscle Relaxants, Centrally Acting, Plain

    DEA CLASS

    Rx

    DESCRIPTION

    Oral and parenteral centrally acting muscle relaxant
    Used as adjunct therapy for acute, painful musculoskeletal conditions and in the management of tetanus
    Studies indicate the drug is not effective for spasticity

    COMMON BRAND NAMES

    Robaxin

    HOW SUPPLIED

    Methocarbamol/Robaxin Intramuscular Inj Sol: 1mL, 100mg
    Methocarbamol/Robaxin Intravenous Inj Sol: 1mL, 100mg
    Methocarbamol/Robaxin Oral Tab: 500mg, 750mg

    DOSAGE & INDICATIONS

    For use as an adjunct to rest, physical therapy, and other measures for the relief of musculoskeletal pain associated with acute, painful musculoskeletal conditions.
    Oral dosage
    Adults and Adolescents 16 years and older

    Initially, 1,500 mg PO 4 times per day for 2 to 3 days (total 6 grams/day PO for the first 24 to 78 hours). Max acute dose (first 48 to 72 hours): 8 grams/day PO for severe conditions. Then, reduce to either 1,000 mg PO 4 times per day, 1,500 mg PO 3 times per day, or, 750 mg PO every 4 hours. Usual maintenance 4 grams/day PO in divided doses. Max maintenance: 4.5 grams/day PO in divided doses.

    Intravenous or Intramuscular dosage
    Adults

    For moderate symptoms, 1 gram IM or IV as a single dose may be adequate. Do not exceed 3 mL/min rate when given IV or inject more than 5 mL IM into each gluteal region. Usual dosing does not exceed 1 gram IM or IV administered every 8 hours for 1 day; may repeat after a drug-free interval of 48 hours. Max for severe cases or when oral therapy is not feasible: 3 grams/day IM or IV for no more than 3 consecutive days.

    For the adjunct treatment of tetanus.
    Intravenous dosage followed by Oral dosage
    Adults

    Initially, 1 to 2 grams IV directly into the tubing of inserted indwelling needle, administered at a rate of 300 mg/minute. An additional 1 to 2 grams IV infusion may be given, for a total initial dose of up to 3 gramsIV. Repeat dosage every 6 hours until a nasogastric (NG) tube can be inserted for oral therapy. The tablets or capsule contents may then be crushed and suspended in water or saline solutions and administered through the NG tube. Dosages of up to 24 grams/day NG/PO may be required.

    Neonates, Infants, Children, and Adolescents

    Initially, 15 mg/kg (or 500 mg/m2) IV every 6 hours, if needed. Do NOT exceed total dose of 1.8 grams/m2/day IV for 3 consecutive days. May be given by IV injection into tubing (max rate undiluted: 3 mL/minute) or by IV infusion. Safety and effectiveness of methocarbamol injection in pediatric patients have not been established except in tetanus.

    MAXIMUM DOSAGE

    Adults

    24 grams/day PO or 12 grams/day IV for tetanus; 8 grams/day PO or 3 grams/day IM/IV for acute muscle spasm and 4.5 grams/day PO in chronic use.

    Geriatric

    24 grams/day PO or 12 grams/day IV for tetanus; 8 grams/day PO or 3 grams/day IM/IV for acute muscle spasm and 4.5 grams/day PO in chronic use.

    Adolescents

    16 years and older: 8 grams/day PO or 3 grams/day IM/IV for acute muscle spasm (first 48 to 72 hours) and 4.5 grams/day PO in chronic use; 1.8 grams/m2/day IV for tetanus.
    Less than 16 years: 1.8 grams/m2/day IV for tetanus; safety and efficacy have not been established for other indications.

    Children

    1.8 grams/m2/day IV for tetanus; safety and efficacy have not been established for other indications.

    Infants

    Safety and efficacy have not been established.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    Specific guidelines for dosage adjustments in hepatic impairment are not available; cautious use is warranted based on reduced elimination in patients with cirrhosis.

    Renal Impairment

    Oral: Cautious use is warranted, particularly in patients with severe renal impairment or those patients on hemodialysis, as the clearance of methocarbamol is reduced.
    Injectable: The use of methocarbamol injection is not recommended in patients with known or suspected renal pathology because of the polyethylene glycol 300 component of the injectable formulation, which is known to have increased pre-existing acidosis and urea retention in patients with renal impairment.

    ADMINISTRATION

    Oral Administration

    May be administered without regard to meals.

    Oral Solid Formulations

    Nasogastric (NG) tube administration: Methocarbamol tablets may be crushed and suspended in water or saline solution to allow for NG administration.

    Injectable Administration

    Methocarbamol is administered intravenously or intramuscularly; do not administer subcutaneously.

    Intravenous Administration

    Intravenous injection:
    May be administered undiluted by direct IV injection at a maximum rate of 300 mg (3 mL of 10% injection) per minute.
    Methocarbamol does not mix with any blood that may be aspirated into the syringe during administration; blood in the syringe can either be injected with the drug or the injection of methocarbamol can be stopped when the plunger reaches the blood.
    Avoid extravasation of this hypertonic solution, which may result in thrombophlebitis.
    The patient should be in a recumbent position during and for at least 10 to 15 minutes following the injection.
    Switch to oral therapy as soon as feasible.
     
    Intravenous infusion:
    Dilute 1 vial (10 mL) with up to 250 mL of 0.9% Sodium Chloride injection or Dextrose 5% injection. Do NOT refrigerate diluted solution.
    Maximum infusion rate is 300 mg/minute.
    Avoid extravasation of this hypertonic solution, which may result in thrombophlebitis.
    The patient should be in a recumbent position during and for at least 10 to 15 minutes following the injection.
    Switch to oral therapy as soon as feasible.
     
    Use in tetanus patients
    Administration appears to have a beneficial effect in the control of the neuromuscular manifestations of tetanus, but does not replace tetanus antitoxin treatment or other usual supportive care for this condition.
    For adults: Give initial doses intravenously directly into the tubing of the previously inserted indwelling needle; do not exceed maximal rates of administration. Once a nasogastric (NG) tube is placed, oral tablets (see NG administration) may then be given through the NG tube as directed.
    For pediatric patients: Initial and maintenance dosages may be given by injection into tubing or by intravenous infusion with an appropriate quantity of fluid. See directions for intravenous use. Do not exceed maximal rates of administration.

    Intramuscular Administration

    Administer undiluted. Do not administer more than 500 mg (5 ml of 10% methocarbamol injection) into each gluteal region.

    STORAGE

    Robaxin:
    - Do not refrigerate
    - Store at controlled room temperature (between 68 and 77 degrees F)

    CONTRAINDICATIONS / PRECAUTIONS

    History of angioedema

    Methocarbamol is contraindicated for use by patients hypersensitive to methocarbamol or to any component of the formulation, such as a history of angioedema or anaphylactic reaction to methocarbamol.

    Renal disease, renal failure, renal impairment

    Methocarbamol injection is contraindicated in patients with known or suspected renal disease pathology of any type, including renal impairment or renal failure; polyethylene glycol 300 is present in the injection and is known to have increased preexisting acidosis and urea retention in patients with renal impairment at larger doses than are present in the injection.

    Coadministration with other CNS depressants, driving or operating machinery, ethanol ingestion

    Methocarbamol can impair mental and/or physical abililties required for performance of hazardous tasks, such as driving or operating machinery. These effects may be additive with ethanol ingestion or coadministration with other CNS depressants. Patients should be cautioned about operating machinery, including automobiles, until they are certain that methocarbamol does not adversely affect their ability to engage in such activities.

    Seizure disorder

    Caution should be observed in using the injectable form of methocarbamol in patients with suspected or a known seizure disorder. The onset of convulsive seizures during intravenous administration of methocarbamol has been reported in patients with seizure disorders. The psychic trauma of the procedure may have been a contributing factor. Although several observers have reported success in terminating epileptiform seizures with methocarbamol injection, its administration to patients with epilepsy is not recommended.

    Hepatic disease

    Cautious use of methocarbamol is warranted for patients with severe hepatic disease. Inpatients with cirrhosis secondary to alcohol abuse, clearance of methocarbamol was significantly reduced, and the half-life prolonged, compared to healthy subjects.

    Extravasation, hypotension

    Since methocarbamol injection is hypertonic, vascular extravasation must be avoided. Extravasation of methocarbamol during intravenous administration may result in thrombophlebitis, sloughing, and pain at the injection site. Careful adherence to the proper dose and rate of administration should be observed. To limit hypotension, syncope, or other vascular reactions, it is preferable that a patient be in a recumbent position during and for at least 10 to 15 minutes following an intravenous dose.

    Pregnancy

    Because pregnancy outcome data are too limited to be conclusive, methocarbamol should not be used in females who are pregnant or may become pregnant and particularly during early pregnancy unless the benefits to the mother outweigh the possible fetal and maternal risks. Safe and effective use during pregnancy or with respect to fetal development has not been established. There have been reports of human fetal and congenital abnormalities following in utero exposure to methocarbamol. In one case, an infant was born with multiple joint contractures after in utero exposure to methocarbamol and propoxyphene for 3 days during the first trimester of pregnancy. In the Collaborative Perinatal Project, 6 infants with inguinal hernia were observed from a total of 119 in utero exposures to methocarbamol at any time during the pregnancies; however, a causal association between the drug and the defect was not established. The effects of methocarbamol during labor and delivery or with regard to fertility or reproduction capacity are unknown.

    Breast-feeding

    Methocarbamol should be used with caution during breast-feeding. Methocarbamol and/or its metabolites are excreted in the milk of dogs; however, it is not known if methocarbamol or its metabolites are excreted in human milk.

    Geriatric

    Use methocarbamol with caution in the geriatric patient due to slight pharmacokinetic alterations observed vs. younger adults. Methocarbamol is not generally preferred for use in geriatric patients because of the potential risk for sedative and anticholinergic side effects, and potential increased sensitivity to the drug. According to the Beers Criteria, skeletal muscle relaxants including methocarbamol are considered potentially inappropriate medications (PIMs) for use in geriatric patients and should be avoided because most muscle relaxants are poorly tolerated by older adults. Some muscle relaxants can cause anticholinergic effects, sedation, and are associated with an increased risk of fractures. In addition, there is questionable effectiveness of the dosages tolerated by older adults. The federal Omnibus Budget Reconciliation Act (OBRA) regulates the use of medications in residents of long-term care facilities. According to the OBRA guidelines, most muscle relaxants are poorly tolerated by older adults due to anticholinergic side effects, sedation, and/or weakness. However, periodic use (e.g., once every 3 months) for no more than 7 days may be appropriate when other interventions or alternative medications are not effective or indicated. Chronic use in individuals with complications due to select conditions may be indicated, although close monitoring is warranted. Abrupt discontinuation of some muscle relaxants may cause or predispose individuals to seizures or hallucinations.

    Children, infants, neonates

    Safety and efficacy in neonates, infants, children and adolescents less than 16 years of age have not been established except for parenteral form of methocarbamol for the indication for the adjunct treatment of tetanus in pediatric patients.

    Laboratory test interference

    Methocarbamol may cause a laboratory test interference by causing a color interference in certain screening tests for 5-hydroxyindoleacetic acid (5-HIAA) using nitrosonaphthol reagent and in screening tests for urinary vanillylmandelic acid (VMA) using the Gitlow method.

    ADVERSE REACTIONS

    Severe

    bradycardia / Rapid / Incidence not known
    angioedema / Rapid / Incidence not known
    anaphylactoid reactions / Rapid / Incidence not known
    seizures / Delayed / Incidence not known

    Moderate

    hypotension / Rapid / Incidence not known
    phlebitis / Rapid / Incidence not known
    confusion / Early / Incidence not known
    amnesia / Delayed / Incidence not known
    jaundice / Delayed / Incidence not known
    nystagmus / Delayed / Incidence not known
    conjunctivitis / Delayed / Incidence not known
    blurred vision / Early / Incidence not known
    hemolysis / Early / Incidence not known
    leukopenia / Delayed / Incidence not known

    Mild

    dyspepsia / Early / 1.0-10.0
    nausea / Early / 1.0-10.0
    metallic taste / Early / 1.0-10.0
    dizziness / Early / 10.0
    drowsiness / Early / 10.0
    flushing / Rapid / Incidence not known
    syncope / Early / Incidence not known
    urticaria / Rapid / Incidence not known
    pruritus / Rapid / Incidence not known
    rash / Early / Incidence not known
    injection site reaction / Rapid / Incidence not known
    vertigo / Early / Incidence not known
    headache / Early / Incidence not known
    insomnia / Early / Incidence not known
    vomiting / Early / Incidence not known
    diplopia / Early / Incidence not known
    fever / Early / Incidence not known
    nasal congestion / Early / Incidence not known
    urine discoloration / Early / Incidence not known

    DRUG INTERACTIONS

    Acetaminophen; Butalbital: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Acetaminophen; Butalbital; Caffeine: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Acetaminophen; Butalbital; Caffeine; Codeine: (Major) Concomitant use of codeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Acetaminophen; Caffeine; Dihydrocodeine: (Major) Concomitant use of dihydrocodeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Acetaminophen; Codeine: (Major) Concomitant use of codeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Acetaminophen; Hydrocodone: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Acetaminophen; Oxycodone: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If oxycodone or oxycodone; naloxone is initiated in a patient taking a skeletal muscle relaxant, use an initial dose of oxycodone at 1/3 to 1/2 the usual dosage and titrate to clinical response; reduced initial doses of oxycodone; naltrexone, aspirin, ASA; oxycodone, and ibuprofen; oxycodone are also recommended. If a decision is made to start treatment with acetaminophen; oxycodone extended-release tabIets, start with 1 tablet PO every 12 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Acetaminophen; Pentazocine: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants. Dosage adjustments of either or both medications may be necessary.
    Acetaminophen; Tramadol: (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Alfentanil: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a skeletal muscle relaxant, use a lower initial dose of the opiate and titrate to clinical response. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Alprazolam: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Ambenonium Chloride: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Amitriptyline; Chlordiazepoxide: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Amobarbital: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Anxiolytics; Sedatives; and Hypnotics: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants. Dosage reduction of one or both agents may be necessary.
    Apomorphine: (Moderate) Apomorphine causes significant somnolence. Concomitant administration of apomorphine and CNS depressants could result in additive depressant effects.
    Aspirin, ASA; Butalbital; Caffeine: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Aspirin, ASA; Butalbital; Caffeine; Codeine: (Major) Concomitant use of codeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Aspirin, ASA; Caffeine; Dihydrocodeine: (Major) Concomitant use of dihydrocodeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Aspirin, ASA; Carisoprodol; Codeine: (Major) Concomitant use of codeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Aspirin, ASA; Oxycodone: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If oxycodone or oxycodone; naloxone is initiated in a patient taking a skeletal muscle relaxant, use an initial dose of oxycodone at 1/3 to 1/2 the usual dosage and titrate to clinical response; reduced initial doses of oxycodone; naltrexone, aspirin, ASA; oxycodone, and ibuprofen; oxycodone are also recommended. If a decision is made to start treatment with acetaminophen; oxycodone extended-release tabIets, start with 1 tablet PO every 12 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Atropine; Difenoxin: (Moderate) Concurrent administration of diphenoxylate/difenoxin with methocarbamol can potentiate the CNS-depressant effects of diphenoxylate/difenoxin. Use caution during coadministration.
    Atropine; Diphenoxylate: (Moderate) Concurrent administration of diphenoxylate/difenoxin with methocarbamol can potentiate the CNS-depressant effects of diphenoxylate/difenoxin. Use caution during coadministration.
    Atropine; Edrophonium: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Atropine; Hyoscyamine; Phenobarbital; Scopolamine: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Azelastine: (Moderate) An enhanced CNS depressant effect may occur when azelastine is combined with other CNS depressants including skeletal muscle relaxants.
    Azelastine; Fluticasone: (Moderate) An enhanced CNS depressant effect may occur when azelastine is combined with other CNS depressants including skeletal muscle relaxants.
    Baclofen: (Moderate) Concomitant use of baclofen with other CNS depressants can result in additive CNS depression.
    Barbiturates: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Belladonna Alkaloids; Ergotamine; Phenobarbital: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Belladonna; Opium: (Major) Concomitant use of opium with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Benzodiazepines: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Brompheniramine; Carbetapentane; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants inlcuding skeletal muscle relaxants.
    Brompheniramine; Guaifenesin; Hydrocodone: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Brompheniramine; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Buprenorphine: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as buprenorphine.
    Buprenorphine; Naloxone: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as buprenorphine.
    Butabarbital: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Butorphanol: (Moderate) Concomitant use of butorphanol with other CNS depressants, such as methocarbamol, can potentiate the effects of butorphanol on respiratory depression, CNS depression, and sedation.
    Cannabidiol: (Moderate) Monitor for excessive sedation and somnolence during coadministration of cannabidiol and methocarbamol. CNS depressants can potentiate the effects of cannabidiol.
    Carbetapentane; Chlorpheniramine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants inlcuding skeletal muscle relaxants.
    Carbetapentane; Chlorpheniramine; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants inlcuding skeletal muscle relaxants.
    Carbetapentane; Diphenhydramine; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants inlcuding skeletal muscle relaxants.
    Carbetapentane; Guaifenesin: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants inlcuding skeletal muscle relaxants.
    Carbetapentane; Guaifenesin; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants inlcuding skeletal muscle relaxants.
    Carbetapentane; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants inlcuding skeletal muscle relaxants.
    Carbetapentane; Phenylephrine; Pyrilamine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants inlcuding skeletal muscle relaxants.
    Carbetapentane; Pseudoephedrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants inlcuding skeletal muscle relaxants.
    Carbetapentane; Pyrilamine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants inlcuding skeletal muscle relaxants.
    Carbinoxamine; Hydrocodone; Phenylephrine: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Carbinoxamine; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Chlordiazepoxide: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Chlordiazepoxide; Clidinium: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Chlorpheniramine; Codeine: (Major) Concomitant use of codeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Major) Concomitant use of dihydrocodeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Chlorpheniramine; Dihydrocodeine; Pseudoephedrine: (Major) Concomitant use of dihydrocodeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Chlorpheniramine; Guaifenesin; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Chlorpheniramine; Hydrocodone: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Chlorpheniramine; Hydrocodone; Phenylephrine: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Chlorpheniramine; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Chlorpromazine: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
    Cholinesterase inhibitors: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Clonazepam: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Clorazepate: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Clozapine: (Moderate) Skeletal muscle relaxants should be combined cautiously with clozapine because they could cause additive depressant effects and possible respiratory depression or hypotension.
    Codeine: (Major) Concomitant use of codeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Codeine; Guaifenesin: (Major) Concomitant use of codeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Codeine; Phenylephrine; Promethazine: (Major) Concomitant use of codeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as promethazine. Combination therapy can cause additive effects of sedation and dizziness, which can impair the patient's ability to undertake tasks requiring mental alertness. Dosage adjustments of either or both medications may be necessary.
    Codeine; Promethazine: (Major) Concomitant use of codeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as promethazine. Combination therapy can cause additive effects of sedation and dizziness, which can impair the patient's ability to undertake tasks requiring mental alertness. Dosage adjustments of either or both medications may be necessary.
    Deutetrabenazine: (Moderate) Advise patients that concurrent use of deutetrabenazine and drugs that can cause CNS depression, such as methocarbamol, may have additive effects and worsen drowsiness or sedation.
    Dexmedetomidine: (Moderate) Due to the anesthetic effects of dexmedetomidine, concurrent use with other CNS depressants, such as skeletal muscle relaxants, could result in additive sedative effects and possibly prolong recovery from anesthesia.
    Dextromethorphan; Promethazine: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as promethazine. Combination therapy can cause additive effects of sedation and dizziness, which can impair the patient's ability to undertake tasks requiring mental alertness. Dosage adjustments of either or both medications may be necessary.
    Diazepam: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Dihydrocodeine; Guaifenesin; Pseudoephedrine: (Major) Concomitant use of dihydrocodeine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Diphenhydramine; Hydrocodone; Phenylephrine: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Donepezil: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Donepezil; Memantine: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Dronabinol: (Moderate) Concomitant use of dronabinol with other CNS depressants, such as methocarbamol, can potentiate the effects of dronabinol on respiratory depression.
    Droperidol: (Major) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as droperidol. Combination therapy can cause additive effects of sedation and dizziness, which can impair the patient's ability to undertake tasks requiring mental alertness. Dosage adjustments of either or both medications may be necessary.
    Edrophonium: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Estazolam: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Ethanol: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with ethanol. Concurrent use can cause additive effects of sedation and dizziness, which can impair the patient's ability to undertake tasks requiring mental alertness.
    Fentanyl: (Major) Concomitant use of fentanyl with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Fluphenazine: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
    Flurazepam: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Gabapentin: (Moderate) Carisoprodol and methocarbamol may intensify the CNS depressive effects of gabapentin, such as drowsiness or dizziness. Patients should limit activity until they are aware of how coadministration affects them.
    Galantamine: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Guaifenesin; Hydrocodone: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Guaifenesin; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Homatropine; Hydrocodone: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Hydrocodone: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Hydrocodone; Ibuprofen: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Hydrocodone; Phenylephrine: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Hydrocodone; Potassium Guaiacolsulfonate: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Hydrocodone; Potassium Guaiacolsulfonate; Pseudoephedrine: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Hydrocodone; Pseudoephedrine: (Major) Concomitant use of hydrocodone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Avoid prescribing opioid cough medications in patients taking a skeletal muscle relaxant. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Hydromorphone: (Major) Concomitant use of hydromorphone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Ibuprofen; Oxycodone: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If oxycodone or oxycodone; naloxone is initiated in a patient taking a skeletal muscle relaxant, use an initial dose of oxycodone at 1/3 to 1/2 the usual dosage and titrate to clinical response; reduced initial doses of oxycodone; naltrexone, aspirin, ASA; oxycodone, and ibuprofen; oxycodone are also recommended. If a decision is made to start treatment with acetaminophen; oxycodone extended-release tabIets, start with 1 tablet PO every 12 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Kava Kava, Piper methysticum: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as kava kava. Combination therapy can cause additive effects of sedation and dizziness, which can impair the patient's ability to undertake tasks requiring mental alertness. Dosage adjustments of either or both medications may be necessary.
    Ketamine: (Moderate) The use of general anesthetics with other CNS depressants, including skeletal muscle relaxants, can potentiate CNS depression and/or increase the risk of developing respiratory depression.
    Levorphanol: (Major) Concomitant use of levorphanol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Reduce the initial dose of levorphanol by approximately 50% or more. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Lofexidine: (Moderate) Monitor for additive hypotension, bradycardia, and sedation during coadministration of lofexidine and methocarbamol. Lofexidine can potentiate the effects of CNS depressants. Patients should be advised to avoid driving or performing any other tasks requiring mental alertness until the effects of the combination are known.
    Lorazepam: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Mepenzolate: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as skeletal muscle relaxants.
    Meperidine: (Major) Concomitant use of meperidine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Meperidine; Promethazine: (Major) Concomitant use of meperidine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as promethazine. Combination therapy can cause additive effects of sedation and dizziness, which can impair the patient's ability to undertake tasks requiring mental alertness. Dosage adjustments of either or both medications may be necessary.
    Mephobarbital: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Mesoridazine: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
    Methadone: (Major) Concomitant use of methadone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Methohexital: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Methscopolamine: (Moderate) CNS depression can be increased when methscopolamine is combined with other CNS depressants such as skeletal muscle relaxants.
    Metyrapone: (Moderate) Metyrapone may cause dizziness and/or drowsiness. Other drugs that may also cause drowsiness, such as methocarbamol, should be used with caution. Additive drowsiness and/or dizziness is possible.
    Midazolam: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Molindone: (Moderate) Molindone may cause central nervous system (CNS) depression thereby having additive effects with other drugs that can cause CNS depression such as methocarbamol. Caution is advisable during concurrent use.
    Morphine: (Major) Concomitant use of morphine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. For extended-release morphine tablets (MS Contin and Morphabond), start with 15 mg every 12 hours. Morphine; naltrexone should be initiated at 1/3 to 1/2 the recommended starting dosage. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Morphine; Naltrexone: (Major) Concomitant use of morphine with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. For extended-release morphine tablets (MS Contin and Morphabond), start with 15 mg every 12 hours. Morphine; naltrexone should be initiated at 1/3 to 1/2 the recommended starting dosage. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Nabilone: (Moderate) Concomitant use of nabilone with other CNS depressants like methocarbamol can potentiate the effects of nabilone on respiratory depression.
    Nalbuphine: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants. Dosage adjustments of either or both medications may be necessary.
    Neostigmine: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Oxazepam: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Oxycodone: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If oxycodone or oxycodone; naloxone is initiated in a patient taking a skeletal muscle relaxant, use an initial dose of oxycodone at 1/3 to 1/2 the usual dosage and titrate to clinical response; reduced initial doses of oxycodone; naltrexone, aspirin, ASA; oxycodone, and ibuprofen; oxycodone are also recommended. If a decision is made to start treatment with acetaminophen; oxycodone extended-release tabIets, start with 1 tablet PO every 12 hours. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Oxymorphone: (Major) Concomitant use of oxymorphone with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Reduce the initial oxymorphone dosage by 1/3 to 1/2. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Pentazocine: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants. Dosage adjustments of either or both medications may be necessary.
    Pentazocine; Naloxone: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants. Dosage adjustments of either or both medications may be necessary.
    Pentobarbital: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Perampanel: (Moderate) Co-administration of perampanel with CNS depressants, including ethanol, may increase CNS depression. The combination of perampanel (particularly at high doses) with ethanol has led to decreased mental alertness and ability to perform complex tasks (such as driving), as well as increased levels of anger, confusion, and depression; similar reactions should be expected with concomitant use of other CNS depressants, such as methocarbamol.
    Perphenazine: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
    Perphenazine; Amitriptyline: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
    Phenobarbital: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Phenothiazines: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
    Phenylephrine; Promethazine: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as promethazine. Combination therapy can cause additive effects of sedation and dizziness, which can impair the patient's ability to undertake tasks requiring mental alertness. Dosage adjustments of either or both medications may be necessary.
    Physostigmine: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Primidone: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Prochlorperazine: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
    Promethazine: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as promethazine. Combination therapy can cause additive effects of sedation and dizziness, which can impair the patient's ability to undertake tasks requiring mental alertness. Dosage adjustments of either or both medications may be necessary.
    Pyridostigmine: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Quazepam: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Remifentanil: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a skeletal muscle relaxant, use a lower initial dose of the opiate and titrate to clinical response. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Rivastigmine: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Secobarbital: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Sedating H1-blockers: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as sedating H1-blockers. Combination therapy can cause additive effects of sedation and dizziness, which can impair the patient's ability to undertake tasks requiring mental alertness. Dosage adjustments of either or both medications may be necessary.
    Sufentanil: (Major) Concomitant use of opiate agonists with skeletal muscle relaxants may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with skeletal muscle relaxants to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a skeletal muscle relaxant, use a lower initial dose of the opiate and titrate to clinical response. If a skeletal muscle relaxant is prescribed for a patient taking an opiate agonist, use a lower initial dose of the skeletal muscle relaxant and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Tacrine: (Major) The effects of cholinesterase inhibitors may be inhibited by methocarbamol. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving cholinesterase inhibitors.
    Tapentadol: (Major) Concomitant use of tapentadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Temazepam: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Thalidomide: (Moderate) Thalidomide frequently causes drowsiness and somnolence and may enhance the sedative activity of methocarbamol.
    Thiethylperazine: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
    Thiopental: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants such as barbiturates. Dosage reduction of one or both agents may be necessary.
    Thioridazine: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
    Tramadol: (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Triazolam: (Moderate) Concurrent use of benzodiazepines and other CNS active medications including skeletal muscle relaxants, can potentiate the CNS effects of either agent. Lower doses of one or both agents may be required. The severity of this interaction may be increased when additional CNS depressants are given.
    Tricyclic antidepressants: (Moderate) Methocarbamol may cause additive CNS depression if used concomitantly with other CNS depressants. Dosage adjustments of either or both medications may be necessary.
    Trifluoperazine: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
    Ziconotide: (Moderate) Due to potentially additive effects, dosage adjustments may be necessary if ziconotide is used with a drug that has CNS depressant effects such as methocarbamol. Coadministration of CNS depressants may increase drowsiness, dizziness, and confusion that are associated with ziconotide.
    Ziprasidone: (Moderate) Ziprasidone has the potential to impair cognitive and motor skills. Additive CNS depressant effects are possible when ziprasidone is used concurrently with any CNS depressant, including methocarbamol.

    PREGNANCY AND LACTATION

    Pregnancy

    Because pregnancy outcome data are too limited to be conclusive, methocarbamol should not be used in females who are pregnant or may become pregnant and particularly during early pregnancy unless the benefits to the mother outweigh the possible fetal and maternal risks. Safe and effective use during pregnancy or with respect to fetal development has not been established. There have been reports of human fetal and congenital abnormalities following in utero exposure to methocarbamol. In one case, an infant was born with multiple joint contractures after in utero exposure to methocarbamol and propoxyphene for 3 days during the first trimester of pregnancy. In the Collaborative Perinatal Project, 6 infants with inguinal hernia were observed from a total of 119 in utero exposures to methocarbamol at any time during the pregnancies; however, a causal association between the drug and the defect was not established. The effects of methocarbamol during labor and delivery or with regard to fertility or reproduction capacity are unknown.

    Methocarbamol should be used with caution during breast-feeding. Methocarbamol and/or its metabolites are excreted in the milk of dogs; however, it is not known if methocarbamol or its metabolites are excreted in human milk.

    MECHANISM OF ACTION

    The exact mechanism of action of methocarbamol is unknown. Unlike neuromuscular blockers, methocarbamol does not have an effect on neuronal conduction, neuromuscular transmission, or muscle excitability. Similar to carisoprodol, chlorzoxazone, and cyclobenzaprine, methocarbamol has no direct effect on skeletal muscle. Its skeletal muscle relaxant effects are probably due to its central nervous system depressant effects. CNS depression leads to sedation and a reduction in skeletal muscle spasms. These effects are accompanied by relief of pain and an increase in the mobility of the affected muscles. Pain relief is postulated to be due to alterations in the perception of pain.

    PHARMACOKINETICS

    Methocarbamol is administered intramuscularly, intravenously, or orally. Once in the systemic circulation, methocarbamol is widely distributed throughout the body. In animal studies, the highest concentrations were attained in the kidney and liver; distribution across the placenta was also observed. It is not known if methocarbamol is excreted in human breast milk. Methocarbamol is extensively metabolized by dealkylation and hydroxylation; conjugation is also likely. Essentially all methocarbamol metabolites are eliminated in the urine. Small amounts of unchanged methocarbamol also are excreted in the urine. The mean plasma elimination half-life is about 1 to 2 hours.

    Oral Route

    After oral administration, methocarbamol is rapidly and completely absorbed from the gastrointestinal tract. Peak blood or serum concentrations occur in approximately 1 to 2 hours. The onset of action is usually within 30 minutes after oral administration.

    Intravenous Route

    After IV administration of methocarbamol the onset of action is almost immediate.

    Intramuscular Route

    Absorption after IM administration of methocarbamol is not known.