title: Bioavailability of orally administered sex steroids used in oral contraception and hormone replacement therapy.
abstract: The concept of bioavailability is discussed with particular references to the sex steroids. Problems encountered in the measurement of bioavailability of these steroids and the various factors that may affect their bioavailability are briefly described. Information regarding the bioavailability of the estrogens and gestogens, some of which are prodrugs, used in oral contraception and hormone replacement therapy is summarized and the implications regarding the clinical use of these steroids are discussed.
authors.affiliation: Royal Postgraduate Medical School, London, UK.
authors.forename: K
authors.initials: K
authors.lastname: Fotherby
mesh_terms: D000042:Absorption; D000284:Administration, Oral; D001682:Biological Availability; D003276:Contraceptives, Oral; D015914:Estrogen Replacement Therapy; D012739:Gonadal Steroid Hormones / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D006801:Humans; D007700:Kinetics; D011372:Progestins / Q000008:administration & dosage / Q000493:pharmacokinetics
chemical_list: D003276:Contraceptives, Oral; D012739:Gonadal Steroid Hormones; D011372:Progestins