What are the contraindications for eperisone?

Eperisone Contraindications

Eperisone is contraindicated in patients with known hypersensitivity to the drug, as it can cause immediate allergic reactions including anaphylaxis, and should be used with extreme caution in pregnant or breastfeeding women due to limited safety data.

Absolute Contraindications

Hypersensitivity Reactions

• Known hypersensitivity or previous allergic reaction to eperisone is an absolute contraindication 1, 2
• Eperisone can induce immediate allergic reactions ranging from urticaria and angioedema to severe anaphylaxis 1
• Anaphylaxis comprises 16.9% of all eperisone-related adverse drug reactions, with a calculated incidence of 0.001% 1
• Reactions typically occur within one hour of oral intake and may include laryngeal edema, hypotension, and other life-threatening manifestations 2
• The mechanism appears to be non-IgE-mediated immediate hypersensitivity, making standard allergy testing (skin prick tests, intradermal tests, and basophil activation tests) often negative despite positive oral provocation tests 1

Relative Contraindications and Special Populations

Pregnancy and Lactation

• Eperisone should be used with extreme caution in pregnant or breastfeeding women due to the absence of adequate safety data 3
• There are no well-controlled studies establishing safety during pregnancy or lactation 3
• The risk-benefit ratio must be carefully considered before prescribing to women of childbearing potential 3

Patients with Multiple Drug Allergies

• Exercise heightened caution in patients with histories of allergic reactions to multiple medications, particularly when muscle relaxants were co-prescribed with NSAIDs 2
• These patients may be at increased risk for eperisone-induced allergic reactions 2

Important Safety Considerations

Gastrointestinal Adverse Effects

• While not absolute contraindications, gastrointestinal side effects occur in 4-5% of patients and may necessitate treatment discontinuation 4, 5
• Minor gastrointestinal reactions are the most common reason for stopping eperisone therapy 4

Diagnostic Approach for Suspected Allergy

• Oral provocation test is the gold standard for confirming eperisone-induced hypersensitivity, as all patients with suspected eperisone-induced anaphylaxis showed positive reactions on oral challenge 1
• Standard allergy testing (SPT, intradermal testing, BAT) has limited utility as these tests are frequently negative even in confirmed cases 1
• Do not rely on skin testing alone to rule out eperisone allergy 1

Clinical Context

• Eperisone is commonly prescribed with NSAIDs for musculoskeletal pain, which may lead to diagnostic confusion when allergic reactions occur 1, 2
• The drug has a favorable CNS safety profile compared to other muscle relaxants, with no sedation or drowsiness reported 4, 5
• Adverse effects are generally less frequent than with alternative muscle relaxants like thiocolchicoside (5% vs 21.25% incidence) 5