Antacid does not reduce the bioavailability of oral contraceptive steroids in women. 1986

J V Joshi, and G M Sankolli, and R S Shah, and U M Joshi

The bioavailability of contraceptive steroids was studied in 12 women who were given an antacid and a contraceptive pill simultaneously. They were given a single pill containing ethinyl estradiol (EE2) 30 micrograms in combination with either norethisterone (NET) acetate 1 mg (n = 6), or levonorgestrel (LNg) 150 micrograms, (n = 6). Blood samples were collected up to 24 hours. Four weeks later the same pill was administered along with a single tablet of antacid (magnesium trisilicate 0.5 g and dried aluminum hydroxide 0.25 g) and blood samples were collected as before. Serum levels of NET, LNg and EE2 were measured by radioimmunoassay. No effect of antacid administration on bioavailability of any contraceptive steroid was observed as judged by peak levels and areas under concentration-time curve (AUC). Incidentally, significantly higher serum concentrations of EE2 were observed when it was administered in combination with NET than with LNg. The possible reasons for this finding are discussed.

UI MeSH Term Description Entries
D009640 Norethindrone A synthetic progestational hormone with actions similar to those of PROGESTERONE but functioning as a more potent inhibitor of ovulation. It has weak estrogenic and androgenic properties. The hormone has been used in treating amenorrhea, functional uterine bleeding, endometriosis, and for CONTRACEPTION. 19-Norpregn-4-en-20-yn-3-one, 17-hydroxy-, (17alpha)-,Ethinylnortestosterone,Norethisterone,Norpregneninolone,Conceplan,Micronor,Monogest,Nor-QD,Norcolut,Norcolute,Norethindrone, (1 beta)-Isomer,Norlutin,Nor QD,NorQD
D009644 Norgestrel A synthetic progestational agent with actions similar to those of PROGESTERONE. This racemic or (+-)-form has about half the potency of the levo form (LEVONORGESTREL). Norgestrel is used as a contraceptive, ovulation inhibitor, and for the control of menstrual disorders and endometriosis. 18,19-Dinorpregn-4-en-20-yn-3-one, 13-ethyl-17-hydroxy-, (17alpha)-(+-)-,DL-Norgestrel,Neogest,Ovrette,Postinor,Wy-3707,DL Norgestrel,Wy 3707,Wy3707
D003277 Contraceptives, Oral, Combined Fixed drug combinations administered orally for contraceptive purposes. Combined Oral Contraceptive,Contraceptive Agents, Female, Combined,Oral Contraceptives, Combined,Combined Oral Contraceptives,Contraceptive, Combined Oral,Contraceptives, Combined Oral,Oral Contraceptive, Combined
D004997 Ethinyl Estradiol A semisynthetic alkylated ESTRADIOL with a 17-alpha-ethinyl substitution. It has high estrogenic potency when administered orally, and is often used as the estrogenic component in ORAL CONTRACEPTIVES. 19-Norpregna-1,3,5(10)-trien-20-yne-3,17-diol, (17alpha)-,Ethynyl Estradiol,Estinyl,Ethinyl Estradiol Hemihydrate,Ethinyl Estradiol, (8 alpha)-Isomer,Ethinyl Estradiol, (8 alpha,17 alpha)-Isomer,Ethinyl Estradiol, (8 alpha,9 beta,13 alpha,14 beta)-Isomer,Ethinyl Estradiol, (9 beta,17 alpha)-Isomer,Ethinyl-Oestradiol Effik,Ethinylestradiol Jenapharm,Ethinyloestradiol,Lynoral,Microfollin,Microfollin Forte,Progynon C,Estradiol, Ethinyl,Estradiol, Ethynyl,Ethinyl Oestradiol Effik,Hemihydrate, Ethinyl Estradiol,Jenapharm, Ethinylestradiol
D005260 Female Females
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000077563 Norethindrone Acetate Acetate ester of norethindrone that is used as a long-term contraceptive (CONTRACEPTIVE AGENTS). Estr-4-en-3-one, 17-(acetyloxy)-17-ethynyl-, (17beta)-,Aygestin,Norethindrone Acetate, (17alpha)-(+-)-isomer,Norethindrone Acetate, (17alpha)-isomer,Norethisterone Acetate,Norlutate
D000328 Adult A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available. Adults
D000863 Antacids Substances that counteract or neutralize acidity of the GASTROINTESTINAL TRACT. Alkalinizing Agent,Antacid,Alkalinizing Agents,Agent, Alkalinizing,Agents, Alkalinizing
D001682 Biological Availability The extent to which the active ingredient of a drug dosage form becomes available at the site of drug action or in a biological medium believed to reflect accessibility to a site of action. Availability Equivalency,Bioavailability,Physiologic Availability,Availability, Biologic,Availability, Biological,Availability, Physiologic,Biologic Availability,Availabilities, Biologic,Availabilities, Biological,Availabilities, Physiologic,Availability Equivalencies,Bioavailabilities,Biologic Availabilities,Biological Availabilities,Equivalencies, Availability,Equivalency, Availability,Physiologic Availabilities

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