What are the adverse effects of Eperisone?

Adverse Effects of Eperisone

Eperisone can cause significant adverse effects including gastrointestinal disturbances, hypersensitivity reactions (including anaphylaxis), and neurological symptoms, though it generally has fewer central nervous system effects compared to other muscle relaxants.

Common Adverse Effects

• Gastrointestinal effects: Nausea, abdominal pain, diarrhea, epigastric pain, and stomach complaints are commonly reported 1, 2, 3
• Neurological effects: Dizziness, light-headedness, occasional vertigo, loss of equilibrium, and mild somnolence may occur, though these are generally less severe than with other muscle relaxants 2, 3
• Cutaneous hypersensitivity reactions: Urticaria, itchiness, angioedema, and skin rash have been reported 4

Serious Adverse Effects

• Anaphylaxis: Eperisone can cause severe anaphylactic reactions, comprising approximately 16.9% of reported adverse drug reactions in pharmacovigilance data from Korea 4
• Cardiovascular effects: Heart palpitations have been reported in some patients 5
• General malaise and fatigue: These symptoms may lead to treatment discontinuation in some patients 5

Pharmacokinetic Considerations

• Eperisone is rapidly absorbed after oral administration (Tmax = 1.6 hours) 6
• It has a short biological half-life of approximately 1.87 hours 6
• The drug undergoes rapid elimination from the body with minimal risk of accumulation, even with repeated dosing 6

Risk Factors and Monitoring

• Patients with a history of hypersensitivity reactions should be monitored closely or avoid the medication 4
• Since eperisone is often prescribed alongside NSAIDs for musculoskeletal disorders, hypersensitivity reactions may be incorrectly attributed to the NSAID rather than eperisone 4

Diagnostic Approach for Suspected Hypersensitivity

• Oral provocation testing has been shown to be positive in patients with eperisone-induced anaphylaxis 4
• Skin prick tests and basophil activation tests have shown negative results in patients with confirmed eperisone-induced anaphylaxis, suggesting a non-IgE-mediated mechanism 4

Clinical Considerations

• Despite adverse effects, eperisone has a more favorable central nervous system side effect profile compared to traditional muscle relaxants 1, 2
• The incidence of eperisone-induced anaphylaxis has been estimated at approximately 0.001% 4
• In clinical trials, discontinuation rates due to adverse effects are relatively low (approximately 4-15% of patients) 1, 5

Advantages Over Other Muscle Relaxants

• Eperisone has minimal sedative effects on the central nervous system compared to other muscle relaxants 1, 2
• It provides both analgesic and muscle relaxant effects, potentially eliminating the need for combination therapy 2
• Its mechanism of action includes inhibition of gamma-efferent firing and local vasodilation, which may contribute to its improved tolerability profile 6

Common Pitfalls in Managing Adverse Effects

• Failing to recognize anaphylaxis as a potential adverse effect of eperisone, especially when co-administered with NSAIDs 4
• Not considering eperisone as the causative agent when gastrointestinal or neurological symptoms develop during treatment for musculoskeletal disorders 2, 3
• Overlooking the possibility of hypersensitivity reactions, which can range from mild skin manifestations to severe anaphylaxis 4