CYP3A4 and cystic fibrosis: Noticeably, caftor drugs are metabolized by cytochrome P450 subtypes CYP3A4 and CYP3A5, which are inhibited by several drugs commonly co-administered in CF patients (ketoconazole, itraconazole, posaconazole, voriconazole, clarithromycin, fluconazole, erythromycin, and verapamil) [15].