Methocarbamol

Administration

• Type: Muscle relaxant; FDA-approved as an adjunct for muscle spasms such as Lower back pain
• Dosage Forms: 500 mg or 750 mg tablet
• Routes of Administration: PO
• Common Trade Names: Robaxin

Adult Dosing

• 500 mg to 1500 mg PO every 8 hours
• IV and IM formulations sometimes used in post-op settings but not commonly in ED

Pediatric Dosing

• Efficacy/safety not established in pediatric population

Special Populations

Pregnancy Rating

• Unknown
• Case reports have found possible teratogenic effects (Hall 1982)

Lactation risk

• Not known

Renal Dosing

• Adult: No exact adjustment noted by manufacturer, but clearance may be decreased in patients with renal impairment
• Pediatric:

Hepatic Dosing

• Adult: No exact adjustment noted by manufacturer, but clearance may be decreased in cirrhosis patients
• Pediatric:

Contraindications

• Allergy to class/drug
• Co-administration with other CNS depressants (benzos, opioids, etc)

Adverse Reactions

• Dizziness
• Confusion
• Weakness
• Bradycardia
• Falls

Pharmacology

• Onset (PO): 30 minutes
• Half-life: 1-2 hours
• Metabolism: Predominantly hepatic
• Excretion: Urinary

Mechanism of Action

• Exact mechanism unknown but theorized to be a CNS-depressant

See Also

• Cyclobenzaprine

References

• Sibrack J, Patel P, Hammer R. Methocarbamol. [Updated 2024 Sep 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK565868/