- Concomitant or anticipated treatment with potent CYP 3A4 inhibitor such a cimetidine, cyclosporine, erythromycin or erythromycin-like drugs (e.g., azithromycin, clarithromycin except short term acute treatment for 1 week or less), diltiazem, itraconazole, ketoconazole or other systemic antifungal agents in the azole class, nefazodone; or potent CYP3A4 inducer including: carbamazepine, modafinil, Phenobarbital, phenytoin, rifampin, St. Johns Wort, and troglitazone.