Is Myonal (tolperisone) effective for treating muscle pain?

Myonal (Tolperisone) for Muscle Pain

Tolperisone shows promise for acute muscle spasm with a favorable side effect profile compared to traditional muscle relaxants, but evidence remains limited and it is not FDA-approved in the United States—making NSAIDs and physical therapy the preferred first-line approach for most muscle pain.

Evidence Quality and Regulatory Status

• Tolperisone is not currently FDA-approved in the United States, though it is undergoing Phase III clinical trials (RESUME-1 study) 1
• The drug is commercially available in Switzerland and other countries where anaphylactic reactions have been documented 2
• Current evidence consists primarily of Phase II data and small comparative trials, lacking the robust guideline support available for established muscle relaxants 3, 4

Efficacy Data

Acute Muscle Spasm

• A Phase II dose-ranging study (STAR trial) showed tolperisone 200 mg three times daily produced statistically significant pain reduction versus placebo (p=0.0040) in acute back muscle spasm 3
• Mean pain score reduction was -4.4 for tolperisone 200 mg TID versus -3.5 for placebo on a numeric rating scale at day 14 3
• Head-to-head comparison with thiocolchicoside demonstrated significantly greater improvement in Lasegue's maneuver on day 3 (p=0.017) and day 7 (p=0.0001), with superior pain reduction both at rest and on movement (p=0.0001) 4

Limitations in Evidence

• Tolperisone provided no relief for post-exercise muscle soreness and actually caused reduced isometric force compared to placebo 5
• The drug appears ineffective for delayed-onset muscle soreness, suggesting its mechanism targets acute spasm rather than general muscle pain 5

Safety Profile Comparison

Advantages Over Traditional Muscle Relaxants

• Somnolence occurred in only 1.2% of tolperisone-treated patients versus 2.6% with placebo—markedly lower than conventional skeletal muscle relaxants 3
• Most common adverse events were headache (7.1%) and diarrhea (2.4%), both mild 3
• Lacks the CNS depression, abuse potential, and controlled substance classification that plague agents like carisoprodol 6, 3

Critical Safety Concerns

• Anaphylactic reactions ranging from urticaria to hypotensive shock have been documented, occurring within one hour of oral intake 2
• All reported anaphylaxis cases involved middle-aged women taking tolperisone for chronic muscle pain 2
• The WHO drug reaction database and Swiss Drug Compendium note that anaphylaxis to tolperisone "is not uncommon" 2

Guideline-Based Treatment Algorithm

First-Line Approach (Preferred)

• NSAIDs are equally effective as muscle relaxants for acute low back pain with fewer adverse effects than muscle relaxants or opioids 7
• Physical therapy and exercise programs demonstrate pain reduction in multiple randomized trials 7
• Acetaminophen can be considered as first-line therapy before any muscle relaxant given comparable efficacy and superior safety 6

Second-Line: Established Muscle Relaxants (If NSAIDs Insufficient)

• Tizanidine has the strongest evidence base with efficacy demonstrated in 8 trials for acute low back pain 8
• Skeletal muscle relaxants show superiority to placebo for short-term pain relief at 2-4 days (RR 1.25, CI 1.12-1.41) and 5-7 days (RR 1.72, CI 1.32-2.22) 7
• Cyclobenzaprine, methocarbamol, or metaxalone are acceptable alternatives without controlled substance classification 6
• Duration limit: All muscle relaxant trials were ≤2 weeks; use only short-term 8

Third-Line: Tolperisone (Investigational)

• Consider only if available in your country and after failure of established therapies
• Dose: 200 mg three times daily based on Phase II data 3
• Duration: Limited to 14 days based on trial data 3
• Screen for drug allergy history given anaphylaxis risk 2

Clinical Pitfalls to Avoid

• Do not use tolperisone for chronic muscle pain or post-exercise soreness—evidence shows no benefit and potential harm with reduced muscle force 5
• Avoid in patients with history of drug allergies, particularly middle-aged women who appear at higher risk for anaphylaxis 2
• Do not assume tolperisone is safer than all alternatives—while CNS effects are minimal, anaphylaxis risk may exceed that of established agents 2, 3
• Insufficient evidence exists for chronic use of any muscle relaxant; if pain persists beyond 2-3 weeks, reassess diagnosis and consider alternative etiologies 7, 8

Context-Specific Considerations

When Tolperisone Might Be Reasonable

• Patients requiring muscle relaxation who cannot tolerate sedation (e.g., those operating machinery, elderly at fall risk) 3
• Acute muscle spasm unresponsive to NSAIDs where traditional muscle relaxants are contraindicated 4
• Geographic availability in countries where the drug is approved and monitored 2

When to Avoid Tolperisone

• Any form of chronic or exercise-related muscle pain 5
• Patients with multiple drug allergies or history of anaphylaxis 2
• First-line therapy—established options have superior evidence and safety profiles 7, 6