title: Effect of low estrogen combination oral contraceptive on metabolism of aspirin and phenylbutazone.
abstract: Plasma levels of aspirin and phenylbutazone were estimated before and during administration of low estrogen combination type oral contraceptive for two menstrual cycles in ten and seven female volunteers, respectively. Aspirin was administered at doses of 300 and 600 mg, while phenylbutazone was administered at a dose of 400 mg. Blood samples were collected at intervals of 1, 2, 4, 6, and 8 h for aspirin and 2, 4, 6, 8, 24, 48, 72, and 80 h for phenylbutazone. Plasma levels, plasma half-life (t1/2), as well as area under curve (AUC) for aspirin after use of oral contraceptive revealed lower values. Phenylbutazone levels were not affected. Repeat studies of plasma t1/2 and AUC for aspirin after discontinuation of oral contraceptive showed values similar to basal levels.
mesh_terms: D000328:Adult; D001241:Aspirin / Q000097:blood / Q000378:metabolism*; D001711:Biotransformation; D003276:Contraceptives, Oral / Q000494:pharmacology*; D003277:Contraceptives, Oral, Combined / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004997:Ethinyl Estradiol / Q000494:pharmacology*; D005260:Female; D006207:Half-Life; D006801:Humans; D009640:Norethindrone / Q000494:pharmacology*; D010653:Phenylbutazone / Q000097:blood / Q000378:metabolism*
chemical_list: D003276:Contraceptives, Oral; D003277:Contraceptives, Oral, Combined; D004997:Ethinyl Estradiol; D010653:Phenylbutazone; D001241:Aspirin; D009640:Norethindrone