Antihypertensives, nitrates, β-blockers, Rauwolfia & digitalis prep, antiarrhythmics, anesth; aprindin HCl, dihydropyridine Ca antagonists, triazolam, midazolam, carbamazepine, theophylline, cyclosporin, tacrolimus hydrate, phenytoin; rifampicin, cimetidine, HIV-PI, & muscle relaxants.