Class: Skeletal muscle relaxant, centrally acting
- Tablets 500 mg
- Injection 100 mg/mL
- Tablets 750 mg
May cause relaxation of skeletal muscle via general CNS depression. Does not directly relax tense skeletal muscles.
T max is 2 h.
Methocarbamol protein binding is 46% to 50%.
Inactive metabolites are excreted in urine and small amounts in feces. The t ½ is 1 to 2 h.
Onset is 30 min.
Special PopulationsRenal Function Impairment
Cl is decreased approximately 40% in patients with severe renal impairment.Hepatic Function Impairment
Cl is decreased approximately 70%; t 1/ 2 is prolonged to approximately 3.4 h in cirrhosis patients.Children
Safety and efficacy in children younger than 16 yr of age not established, except in tetanus.
Indications and Usage
Adjunctive therapy for relief of painful, acute musculoskeletal conditions; control of neuromuscular manifestations of tetanus.
Renal pathologic disorders (parenteral form); standard considerations.
Dosage and AdministrationSkeletal Muscle Relaxation
Adults Initial dose
IV/IM 3 g over no more than 3 consecutive days. Repeat course after 48-h lapse if condition persists. PO 1.5 g 4 times daily.Maintenance
PO 1 g 4 times daily, 750 mg every 4 h, or 1.5 g 3 times daily. For first 48 to 72 h, 6 to 8 g/day is recommended; then reduce to 4 g/day.Tetanus
IV 1 to 2 g; additional 1 to 2 g may be added to infusion up to 3 g total. Repeat every 6 h until oral form may be administered.Children
IV/IV infusion 15 mg/kg initially; then 15 mg/kg every 6 h.
- For IV or IM administration only. Not for intradermal, subcutaneous, or intra-arterial administration.
- Administer direct IV injection of undiluted methocarbamol at max rate of 3 mL/min.
- For IV infusion dilute prescribed dose in no more than 250 mL of sodium chloride injection or 5% dextrose injection.
- Use diluted solution as soon as possible. Do not refrigerate diluted solution for IV administration.
- Administer prescribed IM dose by deep, slow injection into gluteal region. Do not inject more than 5 mL at 1 site. Rotate injection sites.
- Do not administer injection if particulate matter, cloudiness, or discoloration noted.
Store at controlled room temperature (68° to 77°F).
Drug InteractionsAlcohol, CNS depressants
CNS depressant effects may be additive.Anticholinesterase agents (eg, pyridostigmine)
Because effects may be inhibited by methocarbamol, use with caution in patients with myasthenia gravis who are receiving anticholinergic agents.
Laboratory Test InteractionsScreening tests for 5-hydroxy-indoleacetic acid or vanillylmandelic acid
Drug may cause color interference.
Bradycardia; hypotension; syncope; thrombophlebitis.
Headache; amnesia; confusion; dizziness/lightheadedness; drowsiness; insomnia; mild muscular incoordination; sedation; seizures (including grand mal); vertigo.
Flushing; pruritus; rash; urticaria.
Diplopia; nystagmus; blurred vision; conjunctivitis; nasal congestion.
Dyspepsia; nausea; vomiting; metallic taste.
Jaundice (including cholestatic jaundice).
Hypersensitivity reactions, anaphylactic reactions; angioneurotic edema; fever.
Category C .
Safety and efficacy in children younger than 16 yr of age not established, except for management of tetanus.
Frequently occurs in conjunction with alcohol or other CNS depressants and includes nausea, drowsiness, blurred vision, hypotension, seizures, and coma.
- Advise patient or caregiver that injectable medication will be prepared and administered by a health care provider in a medical setting.
- Advise patient that medication will be most effective when combined with rest and prescribed physical therapy.
- Advise patient that dose may be adjusted periodically in order to achieve max benefit.
- Advise patient to take prescribed dose as needed for muscle spasm or limited mobility.
- Advise patient to take without regard to meals but to take with food if stomach upset occurs.
- Instruct patient to avoid alcoholic beverages and sedatives (eg, diazepam) while taking methocarbamol.
- Advise patient that medication may cause urine to turn a dark brown, black, or green and not to be concerned; this is expected and not harmful.
- Advise patient that drug may cause drowsiness or dizziness and to use caution while driving or performing other tasks requiring mental alertness until tolerance is determined.
- Advise patient to stop taking and notify health care provider if any of the following occur: allergic reaction, persistent dizziness, excessive sedation.
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