Current chronic use of medications known to inhibit or induce cytochrome P450, including but not limited to: isoniazid, rifampin, rifabutin, astemizole, terfenadine, cisapride, triazolam, midazolam, nifedipine, diltiazem, verapamil, cimetidine, dexamethasone, carbamazepine, phenytoin, phenobarbital, propoxyphene, quinidine, amiodarone, or ergot alkaloids, azole antifungals (ketoconazole, fluconazole, itraconazole), or macrolide antibiotics (erythromycin, clarithromycin);