- Current or recent use or planned treatment with one of the following: amiodarone, cyclosporine, itraconazole, ketoconazole, erythromycin, clarithromycin, HIV protease inhibitors, nefazodone, cimetidine, danazol, large quantities of grapefruit juice (more than 1 quart daily), verapamil, fibrates, or niacin