title: Letter: Drugs affecting oral contraceptives.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D003276:Contraceptives, Oral / Q000037:antagonists & inhibitors*; D004347:Drug Interactions; D004790:Enzyme Induction / Q000187:drug effects; D004964:Estriol / Q000652:urine; D004967:Estrogens / Q000378:metabolism; D005260:Female; D006801:Humans; D010634:Phenobarbital / Q000494:pharmacology*; D011247:Pregnancy; D012293:Rifampin / Q000494:pharmacology*
chemical_list: D003276:Contraceptives, Oral; D004967:Estrogens; D000667:Ampicillin; D004964:Estriol; D012293:Rifampin; D010634:Phenobarbital