Non-pigmenting fixed drug eruption: a new case due to eperisone hydrochloride

Eperisone-Induced Anaphylaxis: Pharmacovigilance Data and Results of Allergy Testing

PURPOSE

Eperisone is an oral muscle relaxant used in musculoskeletal disorders causing muscle spasm and pain. For more effective pain control, eperisone is usually prescribed together with nonsteroidal anti-inflammatory drugs (NSAIDs). As such, eperisone may have been overlooked as the cause of anaphylaxis compared with NSAIDs. This study aimed to analyze the adverse drug reaction (ADR) reported in Korea and suggest an appropriate diagnostic approach for eperisone-induced anaphylaxis.

METHODS

We reviewed eperisone-related pharmacovigilance data (Korea Institute of Drug Safety-Korea Adverse Event Reporting System [KIDS-KAERS]) reported in Korea from 2010 to 2015. ADRs with causal relationship were selected. Clinical manifestations, severity, outcomes, and re-exposure information were analyzed. For further investigation, 7-year ADR data reported in a single center were also reviewed. Oral provocation test (OPT), skin prick test (SPT) and basophil activation test (BAT) were performed in this center.

RESULTS

During the study period, 207 patients had adverse reactions to eperisone. The most common ADRs were cutaneous hypersensitive reactions (30.4%) such as urticaria, itchiness or angioedema. Fifth common reported ADR was anaphylaxis. There were 35 patients with anaphylaxis, comprising 16.9% of the eperisone-related ADRs. In the single center study, there were 11 patients with eperisone-induced anaphylaxis. All the patients underwent OPT and all the provoked patients showed a positive reaction. Four of the 11 patients with anaphylaxis also underwent SPT and BAT, which were all negative.

CONCLUSIONS

Incidence of eperisone-induced anaphylaxis calculated from the KIDS-KAERS database was 0.001%. Eperisone can cause hypersensitive reactions, including anaphylaxis, possibly by inducing non-immunoglobulin E-mediated immediate hypersensitivity.

Unusual and Interesting Adverse Cutaneous Drug Reactions

Any drug can cause any rash! Cutaneous adverse drug reactions (CADRs) are great mimickers and can be included in the differential diagnosis of any inflammatory dermatoses. Several drugs can cause rash of similar morphology and the same drug can cause rash of different morphology. While some common and specific drug reaction patterns are recognized easily by the clinicians, many a times unusual and interesting patterns can be induced by drug(s), thus leading to erroneous diagnosis and mistreatment. This review aims to familiarize clinicians with some rare, yet interesting patterns of CADR.

Serum concentration of eperisone hydrochloride correlates with QT interval

BACKGROUND

Eperisone hydrochloride is a centrally acting muscle relaxant prescribed for muscle stiffness that acts by depressing the activities of α and γ efferent neurons in the spinal cord and supraspinal structures. Although a case of eperisone-induced severe QT prolongation had been reported, the relationship between serum eperisone concentration and QT interval remains obscure.

OBJECTIVE

The aim of this study was to investigate the relationship between serum eperisone concentration and QT interval.

METHODS

Four patients who overdosed on eperisone were admitted to our hospital between January 2010 and December 2011. We took simultaneous serial measurements of serum eperisone concentration and QT interval in the intensive care unit. In total, 22 measurement points were plotted for these patients. We analyzed the correlation between the serum eperisone concentration and corrected QT (QTc) interval.

RESULTS

Three men and one woman (mean age, 50 years) overdosed on eperisone with an average dose of 3087.5 mg (therapeutic dose, 150 mg/day). The mean QTc interval at arrival was 592 ms (range, 444-825 ms), and the mean serum eperisone concentration at arrival was 1257.5 ng/mL (range, 14.5-4120.0 ng/mL). The correlation coefficient was 0.833 between serum eperisone concentration and QTc interval (P < .001).

CONCLUSION

Serum eperisone concentration correlates with QTc interval in patients who overdose on eperisone.

Oral muscle relaxant may induce immediate allergic reactions

Eperisone and afloqualone act by relaxing both skeletal and vascular smooth muscles to improve circulation and suppress pain reflex. These drugs are typically prescribed with non-steroidal anti-inflammatory drugs (NSAIDs) as painkillers. However, there have been no reports on serious adverse reactions to oral muscle relaxants; and this is the first report to describe three allergic reactions caused by eperisone and afloqualone. All three patients had histories of allergic reactions after oral intake of multiple painkillers, including oral muscle relaxants and NSAIDs, for chronic muscle pain. An open-label oral challenge test was performed with each drug to confirm which drugs caused the systemic reactions. All patients experienced the same reactions within one hour after oral intake of eperisone or afloqualone. The severity of these reactions ranged from laryngeal edema to hypotension. To confirm that the systemic reaction was caused by eperisone or afloqualone, skin prick testing and intradermal skin tests were performed with eperisone or afloqualone extract in vivo, and basophil activity tests were performed after stimulation with these drugs in vitro. In one patient with laryngeal edema, the intradermal test with afloqualone extract had a positive result, and CD63 expression levels on basophils increased in a dose-dependent manner by stimulation with afloqualone. We report three allergic reactions caused by oral muscle relaxants that might be mediated by non-immunoglobulin E-mediated responses. Since oral muscle relaxants such as eperisone and afloqualone are commonly prescribed for chronic muscle pain and can induce severe allergic reactions, we should prescribe them carefully.