- Current use of strong CYP3A inhibitors such as ketoconazole, itraconazole, voriconazole, posaconazole, nefazodone, and clarithromycin are prohibited; NOTE: moderate inhibitors of CYP3A4 should be used with caution; navitoclax is a moderate inhibitor of CYP2C8 and a strong inhibitor of CYP2C9; caution should be exercised when dosing navitoclax concurrently with CYP2C8 and CYP2C9 substrates; common CYP2C8 substrates include paclitaxel, statins and repaglinide; CYP2C9 substrates include celecoxib, phenytoin and warfarin; when possible, investigators should switch to alternative medications or monitor the patients closely