(meth oh KAR ba mole)
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Robaxin: 1000 mg/10 mL (10 mL [DSC])
Robaxin: 1000 mg/10 mL (10 mL) [contains polyethylene glycol 300]
Solution, Injection [preservative free]:
Generic: 1000 mg/10 mL (10 mL)
Robaxin: 500 mg [scored; contains fd&c yellow #6 (sunset yellow), saccharin sodium]
Robaxin-750: 750 mg [contains fd&c yellow #10 (quinoline yellow), fd&c yellow #6 (sunset yellow), saccharin sodium]
Generic: 500 mg, 750 mg
Brand Names: U.S.
- Skeletal Muscle Relaxant
Causes skeletal muscle relaxation by general CNS depression
Hepatic via dealkylation and hydroxylation
Urine (primarily as metabolites)
Onset of Action
Muscle relaxation: Oral: ~30 minutes
Time to Peak
Serum: Oral: 1-2 hours
46% to 50%
Special Populations: Renal Function Impairment
Cl is decreased approximately 40% in patients with severe renal impairment.
Special Populations: Hepatic Function Impairment
Cl is decreased approximately 70%; t1/2 is prolonged ~ 3-fold in cirrhosis patients.
Use: Labeled Indications
Adjunctive treatment of muscle spasm associated with acute painful musculoskeletal conditions (eg, tetanus)
Hypersensitivity to methocarbamol or any component of the formulation; renal impairment (injection formulation)
Children: Recommended only for use in tetanus: 15 mg/kg/dose or 500 mg/m2/dose, may repeat every 6 hours if needed; maximum dose: 1.8 g/m2/day for 3 days only
Adults: Initial dose: 1-2 g by direct IV injection, which may be followed by an additional 1-2 g by infusion (maximum initial dose: 3 g total); followed by 1-2 g every 6 hours until oral administration by mouth or via NG tube is possible; total oral daily doses of up to 24 g may be needed; injection should not be used for more than 3 consecutive days
Oral: Children ≥16 years and Adults: 1.5 g 4 times/day for 2-3 days (up to 8 g/day may be given in severe conditions), then decrease to 4-4.5 g/day in 3-6 divided doses
IM, IV: Adults: Initial: 1 g; may repeat every 8 hours if oral administration not possible; maximum dose: 3 g/day for no more than 3 consecutive days. If condition persists, may repeat course of therapy after a drug-free interval of 48 hours.
Dosage adjustment in renal impairment: No dosage adjustment provided in manufacturer’s labeling. However, administration of the parenteral formulation is contraindicated in patients with renal dysfunction due to the presence of polyethylene glycol.
Dosage adjustment in hepatic impairment: No dosage adjustment provided in manufacturer’s labeling. However, elimination may be reduced in patients with cirrhosis.
Solution for injection: May administer undiluted or diluted in D5W or NS (1 vial/≤250 mL diluent).
Solution for injection:
IM: A maximum of 5 mL can be administered into each gluteal region.
IV: Maximum rate: 3 mL/minute; may be administered undiluted or diluted. Monitor closely for extravasation. Administer IV while in recumbent position. Maintain position for at least 10-15 minutes following infusion.
Tablet: May be crushed and mixed with food or liquid if needed.
Solution for injection: Prior to dilution, store at controlled room temperature of 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F).
Tablet: Store at controlled room temperature of 20°C to 25°C (68°F to 77°F).
Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Monitor therapy
Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination
Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine patches (Butrans brand) at 5 mcg/hr in adults when used with other CNS depressants. Consider therapy modification
Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Exceptions: Levocabastine (Nasal). Monitor therapy
Doxylamine: May enhance the CNS depressant effect of CNS Depressants. Management: The manufacturer of Diclegis (doxylamine/pyridoxine), intended for use in pregnancy, specifically states that use with other CNS depressants is not recommended. Monitor therapy
Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Droperidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (e.g., opioids, barbiturates) with concomitant use. Consider therapy modification
Eperisone: May enhance the adverse/toxic effect of Methocarbamol. Monitor therapy
Hydrocodone: CNS Depressants may enhance the CNS depressant effect of Hydrocodone. Management: Consider starting with a 20% to 30% lower hydrocodone dose when using together with any other CNS depressant. Dose reductions in the other CNS depressant may also be warranted. Consider therapy modification
HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy
Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after clinically effective methotrimeprazine dose is established. Consider therapy modification
Metyrosine: CNS Depressants may enhance the sedative effect of Metyrosine. Monitor therapy
Minocycline: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Mirtazapine: CNS Depressants may enhance the CNS depressant effect of Mirtazapine. Monitor therapy
Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Avoid combination
Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Avoid combination
Perampanel: May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination, until they have experience using the combination. Consider therapy modification
Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Monitor therapy
Pyridostigmine: Methocarbamol may diminish the therapeutic effect of Pyridostigmine. Monitor therapy
ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Monitor therapy
Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Monitor therapy
Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy
Selective Serotonin Reuptake Inhibitors: CNS Depressants may enhance the adverse/toxic effect of Selective Serotonin Reuptake Inhibitors. Specifically, the risk of psychomotor impairment may be enhanced. Monitor therapy
Sodium Oxybate: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to combined use. When combined use is needed, consider minimizing doses of one or more drugs. Use of sodium oxybate with alcohol or sedative hypnotics is contraindicated. Consider therapy modification
Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Consider therapy modification
Tapentadol: May enhance the CNS depressant effect of CNS Depressants. Management: Start tapentadol at a dose of one-third to one-half of the normal dose if being initiated in a patient who is taking another drug with CNS depressant effects. Monitor closely for evidence of excessive CNS depression. Consider therapy modification
Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination
Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Consider therapy modification
May cause color interference in certain screening tests for 5-HIAA using nitrosonaphthol reagent and in screening tests for urinary VMA using the Gitlow method.
Frequency not defined.
Cardiovascular: Bradycardia, flushing, hypotension, syncope
Central nervous system: Amnesia, confusion, coordination impaired (mild), dizziness, drowsiness, fever, headache, insomnia, lightheadedness, sedation, seizures, vertigo
Dermatologic: Angioneurotic edema, pruritus, rash, urticaria
Gastrointestinal: Dyspepsia, metallic taste, nausea, vomiting
Local: Pain at injection site, thrombophlebitis
Ocular: Blurred vision, conjunctivitis, diplopia, nystagmus
Respiratory: Nasal congestion
Miscellaneous: Hypersensitivity reactions including anaphylaxis
Concerns related to adverse effects:
• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).
• Hepatic impairment: Plasma protein binding and clearance are decreased and the half-life is increased in patients with hepatic impairment.
• Renal impairment: Use of IV formulation is contraindicated.
• Seizure disorder: Use injection with caution in patients with a history of seizure disorder.
Concurrent drug therapy issues:
• Sedatives: Effects may be potentiated when used with other sedative drugs or ethanol.
• Elderly: Muscle relaxants are poorly tolerated by the elderly due to potent anticholinergic effects, sedation, and risk of fracture. Efficacy is questionable at dosages tolerated by elderly patients; avoid use (Beers Criteria).
• Pediatric: IV formulation: Recommended only for the treatment of tetanus in pediatric patients.
Dosage form specific issues:
• Injection: Contraindicated in renal impairment. Contains polyethylene glycol. Rate of injection should not exceed 3 mL/minute; solution is hypertonic; avoid extravasation. Vial stopper contains latex.
Monitor closely for extravasation (IV administration).
Pregnancy Risk Factor
Animal reproduction studies have not been conducted. The manufacturer notes that fetal and congenital abnormalities have been rarely reported following in utero exposure. Use during pregnancy only if clearly needed.
• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
• Patient may experience nausea, fatigue, headache, insomnia, rhinitis, dysgeusia, or injection site pain or irritation. Have patient report immediately to prescriber severe asthenia, jaundice, significant dizziness, syncope, bradycardia, chills, pharyngitis, memory impairment, illogical thinking, vision changes, or involuntary eye movements (HCAHPS).
• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.
Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.
More about methocarbamol
- Other brands: Robaxin