What is the most effective muscle relaxant?

From the Guidelines

Cyclobenzaprine is the most effective muscle relaxer for acute low back pain, with a moderate superiority to placebo for short-term pain relief, as evidenced by a higher-quality Cochrane review 1. When considering the best muscle relaxer, several factors come into play, including the specific condition, individual needs, and potential side effects.

• For acute low back pain, cyclobenzaprine (Flexeril) is often considered a first-line option, typically prescribed at 5-10mg taken three times daily for short-term use (2-3 weeks) 1.
• Other effective options include tizanidine, which has been shown to be efficacious for acute low back pain in 8 trials 1.
• Non-medication approaches should be tried first or used alongside medication, including physical therapy, heat/cold therapy, gentle stretching, and adequate rest.
• It's essential to note that skeletal muscle relaxants are associated with a higher total number of adverse events and central nervous system adverse events compared with placebo, although most events are self-limited and serious complications are rare 1.
• The choice of muscle relaxer should be based on individual patient needs and medical history, with careful consideration of potential side effects and interactions.
• As there is insufficient evidence to conclude that any specific muscle relaxant is superior to others for benefits or harms, the selection of a muscle relaxer should be guided by the highest quality evidence available, such as the Cochrane review 1.

From the FDA Drug Label

Cyclobenzaprine HCl relieves skeletal muscle spasm of local origin without interfering with muscle function. Clinical Studies Eight double-blind controlled clinical studies were performed in 642 patients comparing cyclobenzaprine hydrochloride 10 mg, diazepam, and placebo. The efficacy of cyclobenzaprine hydrochloride tablets 5 mg was demonstrated in two seven-day, double-blind, controlled clinical trials enrolling 1405 patients.

The best muscle relaxer is cyclobenzaprine, as it has been shown to be effective in relieving skeletal muscle spasm of local origin without interfering with muscle function, and has been demonstrated to be superior to placebo in several clinical trials 2.

• Key benefits of cyclobenzaprine include its ability to reduce tonic somatic motor activity and its influence on both gamma and alpha motor systems.
• Important considerations include the potential for increased heart rate and the need for dose adjustment in elderly patients or those with hepatic impairment 2.

From the Research

Muscle Relaxers

• Cyclobenzaprine is a muscle relaxant that 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 3.
• A study found that cyclobenzaprine 5 mg TID was as effective as 10 mg TID, and was associated with a lower incidence of sedation 3.
• Another study found that once-daily cyclobenzaprine extended release (CER) 15 and 30 mg was effective in relieving acute muscle spasm, with a lower rate of reported somnolence compared to cyclobenzaprine immediate release (CIR) 10 mg TID 4.

Comparison of Muscle Relaxers

• 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 5.
• The same review found that there is insufficient evidence to determine the relative efficacy or safety of cyclobenzaprine, carisoprodol, orphenadrine, tizanidine, metaxalone, methocarbamol, and chlorzoxazone 5.
• A study found that combination therapy with cyclobenzaprine 5 mg TID plus ibuprofen was not superior to cyclobenzaprine 5 mg TID alone in adult patients with acute neck and back pain with muscle spasm 6.

Safety and Efficacy

• Cyclobenzaprine has been found to be well tolerated, with somnolence and dry mouth being the most common adverse effects, which are mild and dose-related 3, 4.
• A review of a decade of clinical experience with cyclobenzaprine found that it was associated with few serious adverse experiences and represents a cost-effective approach to the management of acute muscle spasm 7.