Last updated: October 29, 2014
Trade Names: Robaxin
Drug Class: Skeletal muscle relaxant
Tablets: 500- and 750 mg
Injection: 100 mg/mL (10 mL)
Dose: Oral: between 2 and 4 g/day in three to six divided doses (the intravenous preparation is rarely indicated in the treatment of musculoskeletal disorders)
Indications: Treatment of painful muscle spasm; fibromyalgia
Mechanism of Action: Reduces spinal nerve traffic to skeletal muscle
Contraindications: Hypersensitivity to methocarbamol, renal impairment
Precautions: Use caution in hepatic and renal dysfunction and patients with seizures.
Pregnancy Risk: C
Common: Dizziness, drowsiness (although methocarbamol is less sedating than other muscle relaxants)
Uncommon: Allergy, flushing, rash, nausea, leukopenia. Urine may turn dark when left to stand.
Increased toxicity of CNS depressants
Patient Instructions: Avoid alcohol; may cause drowsiness
Comments: Nighttime sedative effect is sometimes useful in improving sleep in fibromyalgia. Little high-quality data to support or guide use.
Clinical Pharmacology: Rapid oral absorption; hepatic metabolism; renal excretion. Half-life is 1–2 hours.