Robaxin (Methocarbamol) Adult Dosing
For adults with acute muscle spasms, start with 1500 mg four times daily (6000 mg/day) for the first 48-72 hours, then reduce to 1000 mg four times daily or 1500 mg three times daily (4000 mg/day) for maintenance. 1
Initial Dosing (First 48-72 Hours)
Standard initial dose: 6000 mg per day divided into four doses 1
For severe conditions: up to 8000 mg per day may be administered during the initial 48-72 hour period 1
Maintenance Dosing (After 48-72 Hours)
- Reduce to approximately 4000 mg per day once acute symptoms improve 1
Clinical Efficacy Evidence
Methocarbamol demonstrates approximately 60% efficacy in treating painful muscle spasm, compared to 30% with placebo (p < 0.01) 2
In acute low back pain studies, 44% of methocarbamol-treated patients achieved complete pain relief and discontinued treatment early, compared to only 18% with placebo (p < 0.0001) 3
However, more recent evidence from emergency department studies shows no superiority over placebo when combined with NSAIDs for acute low back pain, with mean RMDQ improvement of 8.1 points versus 10.5 for placebo 4
Important Clinical Considerations
Methocarbamol is the only approved muscle relaxant remaining after recent EMA restrictions led to withdrawal of tetrazepam and limitations on other agents 3
Side effects occur at similar rates to placebo in controlled trials, with no severe adverse effects reported in recent studies 3, 2
The American Geriatrics Society guideline notes that so-called "muscle relaxants" including methocarbamol do not directly relax skeletal muscle and have no evidence of efficacy in chronic pain, making them unfavorable for chronic use in older adults 5
Critical Pitfall to Avoid
Do not use methocarbamol for chronic musculoskeletal pain. These agents lack evidence for chronic pain conditions and carry unnecessary risk in older adults due to sedation and fall risk 5. The drug is FDA-approved and most effective for acute muscle spasm conditions during the first few days of treatment 1, 3.