From the Guidelines
Muscle Relaxant Efficacy
Tizanidine is often considered a muscle relaxer with high efficacy, typically prescribed at a dose of 2-4 mg, taken orally, every 6-8 hours, as needed 1. Alternatively, Cyclobenzaprine, at a dose of 5-10 mg, taken orally, 3 times a day, with a maximum duration of 2-3 weeks, can also be effective 1.
Key Points to Consider
- Efficacy: Both Tizanidine and Cyclobenzaprine have shown efficacy in treating acute low back pain, with Tizanidine being efficacious in 8 trials 1.
- Adverse Events: Skeletal muscle relaxants, including Tizanidine and Cyclobenzaprine, are associated with a higher total number of adverse events and central nervous system adverse events compared to placebo 1.
- Medical Supervision: It's essential to note that muscle relaxers should be used under medical supervision, and the choice of medication depends on individual patient needs and medical history.
- Duration of Therapy: The duration of therapy for muscle relaxants is typically 2 weeks or less, with the exception of a single 3-week trial 1.
Important Considerations
- The choice between Tizanidine and Cyclobenzaprine should be based on individual patient needs and medical history.
- Patients should be monitored for adverse events, particularly central nervous system events, when taking muscle relaxants.
- Muscle relaxants should only be used for a short duration, typically 2-3 weeks, to minimize the risk of adverse events.
From the Research
Efficacy of Muscle Relaxants
- Cyclobenzaprine has been shown to be effective in improving muscle spasm, reducing local pain and tenderness, and increasing range of motion in acute, painful musculoskeletal conditions 2.
- A systematic review found that cyclobenzaprine, carisoprodol, orphenadrine, and tizanidine are effective compared to placebo in patients with musculoskeletal conditions, with cyclobenzaprine being evaluated in the most clinical trials and consistently found to be effective 3.
- The efficacy of cyclobenzaprine is independent of sedation, as a subanalysis found that patients who did not report somnolence still experienced a meaningful treatment effect on all primary efficacy variables 2.
Comparison of Muscle Relaxants
- A systematic review found that there is fair evidence that baclofen, tizanidine, and dantrolene are effective compared to placebo in patients with spasticity, but insufficient evidence to determine the efficacy of dantrolene compared to baclofen or tizanidine 3.
- The same review found that cyclobenzaprine, carisoprodol, orphenadrine, and tizanidine are effective compared to placebo in patients with musculoskeletal conditions, but there is insufficient evidence to determine the relative efficacy or safety of these medications 3.
Pharmacokinetics of Cyclobenzaprine
- A study found that once-daily cyclobenzaprine extended-release (CER) 30 mg and three-times-daily cyclobenzaprine immediate-release (CIR) 10 mg produced comparable systemic exposures to cyclobenzaprine, but pharmacokinetic profiles were qualitatively different 4.
- Another study found that CER 30 mg once daily and CIR 10 mg three times daily resulted in comparable systemic exposures, with CER providing a controlled release of cyclobenzaprine with sustained plasma concentrations 5.