Pharmacokinetics of 10 mg of mifepristone

• Published in: Contraception (Stoneham) Vol. 68; no. 6; pp. 427 - 429
• Main Authors: Leminen, Riikka, Ranta, Sirpa, von Hertzen, Helena, Oehler, Joachim, Heikinheimo, Oskari
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY Elsevier Inc 01.12.2003; Elsevier Science
• Subjects: Adult; Biological and medical sciences; Contraceptives, Postcoital, Synthetic - administration & dosage; Contraceptives, Postcoital, Synthetic - pharmacokinetics; Dose-Response Relationship, Drug; Dose–response relationships; Emergency contraception; Female; Genital system. Reproduction; Humans; Inhibition of ovulation; Medical sciences; Mifepristone - administration & dosage; Mifepristone - pharmacokinetics; Pharmacology. Drug treatments; Radioimmunoassay; Inhibition of ovulation; Dose–response relationships; Radioimmunoassay; Emergency contraception; Human; Healthy subject; Dose-response relationships; Low dose; Single dose; Oral administration; Antihormone; Abortifacient; Antiprogesterone; Female; Mifepristone; Pharmacokinetics
• DOI: 10.1016/S0010-7824(03)00181-1
• ISSN: 0010-7824

The results of several randomized studies have verified the efficacy of 10 mg mifepristone in emergency contraception. In the present study we characterized the pharmacokinetics of 10 mg mifepristone. Eight healthy female volunteers received a single oral dose of mifepristone on the day 10 or 11 of their menstrual cycle. Blood samples were collected at 0, 1, 2, 4 and 8 h, daily for the next 6 days and on day 10 after mifepristone. Mifepristone concentrations were determined by radioimmunoassay preceded by column chromatography. A peak level of 1.41 ± 0.31 μmol/L (mean ± SD) was measured at 1 h. Individual elimination phase half-lives varied from 15.3 to 26.8 h, the mean (± SD) value being 19.6 ± 4.50 h. Serum mifepristone concentrations exceeded 10 nmol/L in all volunteers for an average of 4.9 days. The pharmacokinetic data on 10 mg mifepristone are in line with previous pharmacokinetic and clinical data, and encourage further development of the 10-mg dose in emergency contraception.