Methocarbamol Causes the Least Sedation Among Central Muscle Relaxants
Methocarbamol is the optimal choice when minimizing sedation is the priority, as it is specifically recognized as less sedating while maintaining efficacy for musculoskeletal conditions. 1
Evidence-Based Sedation Profile
Least Sedating Options
- Methocarbamol is explicitly identified as less sedating compared to other skeletal muscle relaxants, making it the preferred agent when sedation must be minimized 1
- Metaxalone is also recognized as less sedating, though effectiveness evidence is more limited than for methocarbamol 1
Most Sedating Agents to Avoid
- Cyclobenzaprine and tizanidine have prominent sedative properties that may benefit patients with insomnia but are problematic when sedation must be avoided 1
- Carisoprodol carries additional concerns beyond sedation, including tolerance, dependence, withdrawal symptoms, and abuse potential, making it particularly inappropriate 2
- Orphenadrine has anticholinergic properties causing confusion, anxiety, and sedation, especially problematic in elderly patients 2
Critical Safety Considerations
Geriatric Population
- The 2019 American Geriatrics Society Beers Criteria specifically lists cyclobenzaprine, methocarbamol, chlorzoxazone, orphenadrine, and carisoprodol as potentially inappropriate medications in older adults due to increased risk of sedation and CNS adverse events 2
- Tizanidine and baclofen are notably NOT on the Beers list, but tizanidine still carries significant sedative properties 3
- All muscle relaxants increase fall risk in older adults through sedation and dizziness 2
Central Nervous System Adverse Events
- Skeletal muscle relaxants as a class are associated with 2-fold increased risk of CNS adverse events (primarily sedation) compared to placebo (RR 2.04,95% CI 1.23-3.37) 2
- Drowsiness, dizziness, and somnolence are consistently reported across all agents 2, 4
Agents with Limited Evidence for Musculoskeletal Pain
Antispasticity Drugs
- Baclofen and dantrolene have only sparse evidence (2 trials) for low back pain, as these are primarily designed for upper motor neuron syndromes, not peripheral musculoskeletal conditions 2, 5
- These agents should generally be avoided for routine musculoskeletal pain 5
Chlorzoxazone
- Very limited or inconsistent data regarding effectiveness compared to placebo for musculoskeletal conditions 6
- Has been associated with rare but serious hepatotoxicity 6
Duration of Use Considerations
- All muscle relaxant trials were 2 weeks or less in duration, indicating these agents should only be used short-term regardless of which agent is selected 2, 5
- There is insufficient evidence for chronic use of any muscle relaxant for musculoskeletal pain 5
Perioperative Management
- The Society for Perioperative Assessment and Quality Improvement recommends holding methocarbamol, cyclobenzaprine, and metaxalone on the day of surgical procedures due to sedative effects and potential interactions with anesthetic agents 2
- This further underscores the sedative burden of these medications, with methocarbamol still being the least problematic option 2