title: [Estrogens. Contraceptive therapy].
abstract: To evaluate the competitive molecular phenomenon of Ethynyl-Estradiol (EE-2) from contraceptive formulations against the endogenous Estradiol (E-2) at the intra and the extracellular compartments, plasma and endometrial samples were simultaneously obtained on different days of the pseudomenstrual cycle from oral contraceptive users under EE-2+ Norgestrel (30 micrograms/+ 500 micrograms) and EE-2+ Norethindrone (50 micrograms + 1.0 mg) in order to quantify EE-2 & E-2. When measuring both molecules it was shown that the chronic administration of steroids regardless of the pharmacological action of the progestin component the lower content of EE-2 (30 micrograms) does not compete substantially at the circulating level permitting the cyclic fashion of the natural estradiol while at the endometrial compartment such phenomenon is not seen thus, a local infertility effect should be reconsidered to anticipate a different approach in the future of contraception.
authors.affiliation: IMSS, Unidad de Investigación Médica en Enfermedades Gonadales, Hospital de Gineco Obstetricia, Luis Castelazo Ayala, México, D.F.
authors.forename: I
authors.initials: I
authors.lastname: Sojo-Aranda
authors.forename: V
authors.initials: V
authors.lastname: Cortés-Gallegos
mesh_terms: D000293:Adolescent; D000328:Adult; D003276:Contraceptives, Oral / Q000032:analysis* / Q000097:blood; D004717:Endometrium / Q000737:chemistry; D004997:Ethinyl Estradiol / Q000032:analysis* / Q000097:blood; D005260:Female; D006801:Humans; D009640:Norethindrone / Q000032:analysis* / Q000097:blood; D009644:Norgestrel / Q000032:analysis* / Q000097:blood
chemical_list: D003276:Contraceptives, Oral; D009644:Norgestrel; D004997:Ethinyl Estradiol; D009640:Norethindrone
vernacular_title: Estrógenos. Terapia anticonceptiva.