A suspected case of autoinduction of voriconazole metabolism in a patient with cerebral aspergillosis

OBJECTIVE This study aims to report a case of accelerated metabolism of voriconazole in a patient with cerebral aspergillosis. CASE SUMMARY A 36-year-old woman developed cerebral aspergillosis after immunosuppressive treatment for suspected atypical hemolytic uremic syndrome/thrombotic thrombocytopenic purpura. She was treated with voriconazole using therapeutic drug monitoring to guide dosing. After an initial high level, her dose was reduced, but over the following weeks, she required several dose increases in order to achieve a voriconazole level within the target range. The patient's dose requirements eventually stabilized at 700 mg twice daily. Cimetidine and omeprazole were added in an effort to inhibit the metabolism of voriconazole. DISCUSSION The metabolism of voriconazole is known to be highly variable among different patients depending on pharmacogenetic factors; however, an increasing rate of voriconazole metabolism in a single patient over time is not well recognized. Therapeutic drug monitoring of voriconazole in this case facilitated the use of large doses while controlling for toxicity. CONCLUSION This case is further evidence of autoinduction in voriconazole metabolism. Therapeutic drug monitoring of voriconazole is useful in detecting variation in a patient's metabolism of voriconazole over time.