Recommended Dosage of Robaxin (Methocarbamol) for Muscle Spasms
The recommended initial dosage of Robaxin (methocarbamol) for adults is 1500 mg (three 500 mg tablets) four times daily or 1500 mg (two 750 mg tablets) four times daily for the first 48-72 hours of treatment, followed by a maintenance dose of 1000 mg (two 500 mg tablets) four times daily or 750 mg (one 750 mg tablet) every 4 hours or 1500 mg (two 750 mg tablets) three times daily. 1
Dosage Regimen
- Initial therapy should provide 6 grams per day for the first 48-72 hours (for severe conditions, up to 8 grams per day may be administered) 1
- After the initial treatment period, the dosage can usually be reduced to approximately 4 grams per day 1
- The medication is available in two strengths:
Clinical Efficacy
- Methocarbamol has been shown to be effective in approximately 60% of patients with painful muscle spasm compared to 30% with placebo (p<0.01) 2
- In a randomized controlled study of acute low back pain with muscle spasms, 44% of patients taking methocarbamol achieved complete pain relief compared to only 18% of those on placebo 3
- The medication is well-established for the treatment of low back pain associated with myofascial components 3
Safety Considerations and Precautions
- Methocarbamol should be held on the day of surgery according to the Mayo Clinic Proceedings 4
- Common adverse effects include drowsiness, dizziness, and potential cardiovascular effects including bradycardia and hypotension 4
- Methocarbamol elimination is significantly impaired in patients with liver and kidney disease, requiring dosage adjustments 4
- The medication may interfere with the effects of pyridostigmine bromide and should not be used in patients with myasthenia gravis 4
- Side effects are generally mild and occur at a rate similar to placebo in clinical trials 2
Important Warnings
- Methocarbamol should not be combined with alcohol, as this interaction can lead to combined central nervous system depression due to interactive sedative-hypnotic properties, which can be potentially fatal 5
- Caution should be exercised when using methocarbamol in elderly patients due to increased risk of adverse effects 6
- The medication may cause drowsiness and impair the ability to drive or operate machinery 4
Alternative Options
- For patients who cannot tolerate methocarbamol or have contraindications, cyclobenzaprine may be considered, though it has more pronounced anticholinergic effects 7
- Baclofen (starting at 10 mg/day with weekly increases up to 30 mg/day) may be more appropriate for severe muscle cramps 7
Methocarbamol remains one of the most commonly prescribed muscle relaxants due to its relatively favorable side effect profile compared to other agents in this class 8. When prescribing, always consider the patient's renal and hepatic function, concomitant medications, and potential for sedation.