title: Ethinyl estradiol and 17β-estradiol in combined oral contraceptives: pharmacokinetics, pharmacodynamics and risk assessment.
abstract: The need to seek improved combined oral contraceptive (COC) efficacy, with fewer health risks and better acceptability, has been ongoing since the introduction of COCs more than 50 years ago. New progestin formulations combined with lower doses of ethinyl estradiol (EE), the predominant estrogenic component of COCs, have reduced the incidence of venous thromboembolism and other negative outcomes of COC treatment. Previous attempts to use endogenous 17β-estradiol (E₂) instead of EE were limited primarily by poor cycle control. The recent introduction of E₂-based formulations has renewed interest to determine if there are potential benefits of using E₂ in COCs. These formulations have been shown to have similar efficacy and cycle control as EE-based COCs. This review provides a brief summary of the pharmacology of EE and E₂, including metabolism, pharmacokinetics and pharmacodynamics, as well as adverse effects of these estrogens.
authors: Departments of Obstetrics and Gynecology and Preventive Medicine, University of Southern California Keck School of Medicine, Los Angeles, CA 90033, USA. fstanczyk@socal.rr.com
authors: Frank Z
authors: FZ
authors: Stanczyk
authors: David F
authors: DF
authors: Archer
authors: Bhagu R
authors: BR
authors: Bhavnani
mesh_terms: D003277:Contraceptives, Oral, Combined / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004958:Estradiol / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000493:pharmacokinetics* / Q000494:pharmacology; D004967:Estrogens / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology; D004997:Ethinyl Estradiol / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology; D005260:Female; D006801:Humans; D008597:Menstrual Cycle / Q000187:drug effects / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism; D011372:Progestins / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology; D018570:Risk Assessment
chemical_list: D003277:Contraceptives, Oral, Combined; D004967:Estrogens; D011372:Progestins; D004997:Ethinyl Estradiol; D011374:Progesterone; D004958:Estradiol