- Concomitant administration of potent cytochrome P450 isoenzyme 3A4 inhibitors (e.g. itraconazole, ketoconazole, fluconazole, posaconazole, Human Immunodeficiency Virus (HIV) protease inhibitors (e.g. nelfinavir), erythromycin, clarithromycin, telithromycin and nefazodone)