Warfarin (Coumadin)

Phenytoin (Dilantin)

Propranolol (Inderal)

Calcium channel blockers

Chlordiazepoxide (Librium)

Diazepam (Valium)

Metronidazole (Flagyl)

Lidocaine (Xylocaine)

Theophylline

Certain tricyclic antidepressants