Recommended Dosage and Frequency of Methocarbamol (Robaxin)
For adults with muscle spasm, the recommended initial dosage of methocarbamol is 1500 mg (three 500 mg tablets) four times daily for the first 48-72 hours, followed by a maintenance dosage of 1000 mg (two 500 mg tablets) four times daily. 1
Dosing Guidelines
Initial Therapy
- 500 mg tablets: 3 tablets four times daily (6 grams/day)
- 750 mg tablets: 2 tablets four times daily (6 grams/day)
Maintenance Therapy
- 500 mg tablets: 2 tablets four times daily (4 grams/day)
- 750 mg tablets: 1 tablet every 4 hours or 2 tablets three times daily (4-4.5 grams/day)
For Severe Conditions
- Up to 8 grams daily may be administered during the initial 48-72 hour period 1
- After this initial period, dosage should be reduced to approximately 4 grams daily
Important Clinical Considerations
Safety Precautions
- Alcohol interaction: Avoid concurrent use of alcohol as this combination can lead to dangerous central nervous system depression due to interactive sedative-hypnotic properties 2
- Renal impairment: The intravenous formulation contains polyethylene glycol (PEG) which has been associated with potential metabolic acidosis and nephrotoxicity in patients with renal impairment 3
Side Effects
- Common side effects include drowsiness and dry mouth 4
- In clinical trials, approximately 60% of patients experienced effective relief compared to 30% with placebo 5
Special Populations
- Elderly patients: Consider starting at the lower end of the dosing range due to potential for increased sensitivity to CNS effects
- Hepatic impairment: May be used in patients with liver cirrhosis for muscle cramps with careful monitoring 4
Duration of Therapy
- Therapy should be limited to the shortest duration necessary to achieve symptom relief
- Reassess the need for continued therapy after 2-3 weeks
Monitoring
- Monitor for signs of excessive sedation, especially when initiating therapy
- Assess therapeutic response within 48-72 hours to determine if dose adjustment is needed
Methocarbamol is primarily indicated for the relief of discomfort associated with acute, painful musculoskeletal conditions. Its effectiveness is enhanced when combined with rest, physical therapy, and other measures to relieve discomfort.