Hong Lu,* Yanmei Mao,* Ying Zeng, Pengyu Li, Pan Yan, Qunzhi Shi, Lin Liu

Department of Pharmacy, The Affiliated Changsha Central Hospital, Hengyang Medical School, University of South China, Changsha, Hunan, People’s Republic of China

*These authors have contributed equally to this work

Correspondence: Hong Lu, Department of Pharmacy, The Affiliated Changsha Central Hospital, Hengyang Medical School, University of South China, Changsha, Hunan, People’s Republic of China, Email 1430368@qq.com

Purpose: Voriconazole, a first-line therapeutic agent for chronic pulmonary aspergillosis, is metabolized by the cytochrome 450 enzymes, specifically CYP2C19 and CYP3A4. Rifampicin and rifapentine act as inducers of the cytochrome P450 enzyme. The current study explored the potential drug interactions arising from the co-administration of voriconazole with either rifampicin or rifapentine, as well as the duration of this effect on serum voriconazole levels after discontinuation of rifampicin or rifapentine.
Patients and Methods: A retrospective study was conducted in tuberculosis patients with chronic pulmonary aspergillosis. These patients underwent a combination therapy involving voriconazole and rifampicin or rifapentine, or they were treated with voriconazole after discontinuation of rifampicin or rifapentine. The serum concentrations of voriconazole at steady-state were monitored. Data on demographic characteristics and the serum voriconazole levels were used for statistical analyses.
Results: A total of 124 serum voriconazole concentrations from 109 patients were included in the study. The average serum concentration of voriconazole fell below the effective therapeutic range in patients treated with both voriconazole and rifampicin or rifapentine. Notably the co-administration of rifapentine led to a substantial (> 70%) decrease in serum voriconazole levels in two patients. Moreover, this interfering effect persisted for at least 7 days following rifampicin discontinuation, while it endured for 5 days or more after discontinuation of rifapentine.
Conclusion: Concomitant use of voriconazole and rifampicin or rifapentine should be avoided, and it is not recommended to initiate voriconazole therapy within 5 or 7 days after discontinuation of rifapentine or rifampicin. Therapeutic drug monitoring not only provides a basis for the adjustment of clinical dose, but also serves as a valuable tool for identifying drug interactions.

Keywords: voriconazole, rifampicin, rifapentine, serum concentration, discontinuation