7. Use of any of the following known inducers or inhibitors of cytochrome P450 3A4 (CYP3A4): phenobarbital, carbamazepine, rifampin, erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, St. John's Wort preparations (Hypericum perforatum), and grapefruit juice