May change amantadine, ketamine, dextromethorphan, dantrolene, baclofen, cimetidine, ranitidine, procainamide, quinidine, quinine, nicotine, hydrochlorothiazide (or any combination w/ hydrochlorothiazide), anticholinergics, anticonvulsants, barbiturates, dopaminergic agonists (eg, L-dopa, bromocriptine), neuroleptics, oral anticoagulants.