Flexeril (Cyclobenzaprine) Dosing and Usage
Start with cyclobenzaprine 5 mg three times daily for most patients, with the option to increase to 10 mg three times daily based on response, but limit treatment duration to 2-3 weeks maximum. 1
Standard Dosing Regimen
- Initial dose: 5 mg orally three times daily for most patients 1
- Titration: May increase to 10 mg three times daily if inadequate response after initial dosing 1
- Duration: Limit use to 2-3 weeks maximum - all clinical trials supporting cyclobenzaprine were 2 weeks or less in duration, and there is insufficient evidence for chronic use 2, 1
Special Population Adjustments
Elderly Patients
- Use 5 mg three times daily with less frequent dosing intervals in elderly patients due to increased risk of anticholinergic effects and sedation 1
- The American Geriatrics Society recommends avoiding cyclobenzaprine entirely in older adults due to anticholinergic effects and fall risk 3
Hepatic Impairment
- Mild hepatic impairment: Start with 5 mg and titrate slowly upward 1
- Moderate to severe hepatic impairment: Cyclobenzaprine is not recommended due to lack of safety data 1
Clinical Efficacy Evidence
- The 5 mg three times daily dose is as effective as 10 mg three times daily with significantly lower rates of sedation (somnolence reported in 54.1% vs 61.8% of patients) 4
- Onset of relief occurs within 3-4 doses of the 5 mg regimen 4
- Efficacy is independent of sedation - meaningful treatment effects were observed in patients who did not report somnolence, indicating the therapeutic benefit is not simply from sedative properties 4
Extended-Release Formulation Alternative
- Cyclobenzaprine extended-release 15-30 mg once daily is an alternative that provides comparable efficacy to immediate-release formulations 5, 6
- Lower rates of daytime drowsiness with extended-release (0.8-1.6%) compared to immediate-release 10 mg three times daily (7.3%) 6
Combination Therapy Considerations
- Adding ibuprofen to cyclobenzaprine provides no additional benefit over cyclobenzaprine monotherapy for acute neck or back pain with muscle spasm 7
- Concomitant NSAIDs increase side effects (primarily drowsiness) without enhancing clinical effect 1
Safety and Discontinuation
- If used long-term (beyond recommended 2-3 weeks), taper gradually over 2-3 weeks to prevent withdrawal symptoms including malaise, nausea, and headache 3
- Hold cyclobenzaprine on the day of surgery due to potential interactions with sedatives and anesthetic agents 3
- Central nervous system adverse events occur 2.04 times more frequently than placebo, including drowsiness and dizziness 3
When Cyclobenzaprine Fails
- Switch to tizanidine as the first alternative - it has the strongest evidence base among alternative muscle relaxants with 8 trials supporting its use in acute low back pain 2
- Avoid baclofen and dantrolene for musculoskeletal pain as these are primarily antispasticity agents for upper motor neuron syndromes with sparse evidence for muscle spasm 2
Common Pitfalls to Avoid
- Do not prescribe beyond 2-3 weeks - there is no evidence supporting chronic use and risk of dependence increases 2, 1
- Do not use in elderly patients without careful consideration of fall risk and anticholinergic burden 3
- Do not combine with other CNS depressants without close monitoring for excessive sedation 1