Ethanol, nicotine Heavy metals: lead, arsenic, lithium Hormones: testosterone, diethylstilbestrol, amnestic progesterone Stimulants: cannabis, cocaine, caffeine Alkylating agents (such as cyclophosphamide) Aspirin (high dose) Allopurinol Monoamine oxidase inhibitors Tranquilizers Furantoin Calcium channel blockers Phenytoin Metacycline Ampicillin Sulfasalazine Colchicine Dibromochloropropane (insecticide) Tricyclic antidepressants Valproic acid