- Subjects who have taken any drugs known to induce or inhibit hepatic drug metabolism within 30 days prior to administration of the study medication (examples of inducers: barbiturates, carbamazepine, phenytoin, glucocorticoids, rifampin/rifabutin; examples of inhibitors: antidepressants, cimetidine, diltiazem, erythromycin, ketoconazole, MAO inhibitors, neuroleptics, verapamil, quinidine).