What is the most effective muscle relaxant?

From the Guidelines

Tizanidine is the most effective muscle relaxant for acute low back pain, with moderate superiority to placebo for short-term pain relief. Based on the evidence from a higher-quality Cochrane review 1, tizanidine was found to be efficacious for acute low back pain in 8 trials. The review also noted that skeletal muscle relaxants were associated with a higher total number of adverse events and central nervous system adverse events compared to placebo, but most events were self-limited and serious complications were rare. Some key points to consider when prescribing tizanidine include:

• The typical dosage is 2-4 mg every 6-8 hours
• It reduces spasticity by increasing presynaptic inhibition
• Common side effects include drowsiness, dizziness, and dry mouth
• Patients should avoid driving or operating machinery until they know how the medication affects them
• Muscle relaxants should be used alongside other treatments like physical therapy, heat/cold therapy, and gentle stretching for best results. Other options like cyclobenzaprine, methocarbamol, and baclofen may also be effective, but the evidence for these medications is not as strong as it is for tizanidine 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 relaxant cannot be determined as the FDA drug label does not compare cyclobenzaprine to all other muscle relaxants. However, cyclobenzaprine is effective in relieving skeletal muscle spasm of local origin.

• It has been compared to diazepam in clinical studies, with some studies showing cyclobenzaprine to be more effective, and others showing comparable effectiveness.
• Cyclobenzaprine has been shown to be effective in clinical trials, with a dose of 5 mg being sufficient to produce significant improvement in patients with muscle spasm 2. The information provided is limited to cyclobenzaprine and does not allow for a comparison to other muscle relaxants 2.

From the Research

Types of Muscle Relaxants

• There are several types of muscle relaxants, including cyclobenzaprine, baclofen, tizanidine, dantrolene, carisoprodol, orphenadrine, metaxalone, methocarbamol, and chlorzoxazone 3
• These muscle relaxants are used to treat different types of conditions, including spasticity and musculoskeletal conditions 3

Efficacy of Muscle Relaxants

• Cyclobenzaprine has been found to be effective in treating musculoskeletal conditions, including acute back or neck pain 3
• Baclofen, tizanidine, and dantrolene have been found to be effective in treating spasticity, primarily in patients with multiple sclerosis 3, 4
• Tizanidine and baclofen have been compared in a randomized, double-blind, cross-over trial, with baclofen being judged as superior by neurologists and physiotherapists 4

Adverse Effects of Muscle Relaxants

• Cyclobenzaprine has been found to cause sedative effects, including drowsiness, due to its non-competitive antagonism of histamine H1 receptors 5
• Tizanidine has been found to cause dry mouth and somnolence, while baclofen has been found to cause muscle weakness 3, 4
• Dantrolene and chlorzoxazone have been associated with rare serious hepatotoxicity 3

Choosing a Muscle Relaxant

• The choice of muscle relaxant should be based on the patient's specific condition, side-effect profile, patient preference, abuse potential, and possible drug interactions 6
• Cyclobenzaprine is the most heavily studied muscle relaxant and has been found to be effective for various musculoskeletal conditions, but may cause sedative effects 3, 6