Clinical characteristics of eperisone-induced immediate-type hypersensitivity

Background: Eperisone is a commonly prescribed oral muscle relaxant, but few studies have been conducted of eperisone-induced hypersensitivity reactions. Objective: The purpose of this study was to investigate the clinical manifestations of eperisone-induced immediate-type hypersensitivity, and to evaluate the role of an intradermal test (IDT) in eperisone-induced anaphylaxis. Methods: This study was based on a retrospective review of medical records from 23 patients diagnosed as eperisone-induced immediate-type hypersensitivity with certain or probable causality. Intradermal tests were performed with a sterile 10 mg/mL eperisone solution. Results: Immediate-type hypersensitivity reactions to eperisone occurred within 15 minutes in 8.7%, within 30 minutes in 52.2%, and within 60 minutes in 82.6% of the patients, cumulatively. All patients showed cutaneous symptoms. Gastrointestinal symptoms were the second-most frequent (65.2%), respiratory symptoms (56.5%) followed, and cardiovascular symptoms were the least (39.1%). Nine (39.1%) patients were categorized as severe anaphylaxis. The mean onset time of severe anaphylaxis was 28.89 minutes, which was significantly shorter than non-severe anaphylaxis (p = 0.011). Five patients among the severe anaphylaxis group were evaluated with IDT, and all showed positive results. In contrast, all of the four patients who have done IDT among the moderate anaphylaxis group showed negative results. There was a significant relationship between severe anaphylaxis and positive IDT results (p = 0.008). Conclusions: Eperisone-induced immediate-type hypersensitivity is not uncommon in Korea, and the IDT could be a useful and safe diagnostic tool, especially in severe anaphylaxis.