 Treatment with any medication known to alter the activity of the CYP3A4 enzyme including ketoconazole, itraconazole, grapefruit juice, erythromycin, clarithromycin, cimetidine, verapamil, diltiazem, rifampin, phenytoin, phenobarbital, or carbamazepine within the previous 2 months and for the duration of the study is prohibited. 