An investigation of the pharmacokinetics of ethynylestradiol in women using radioimmunoassay

Contraception
D J BackM J Watts

Abstract

A radioimmunoassay for ethynylestradiol (EE) which is applicable to plasma samples obtained from women, who have taken a combination type oral contraceptive, has been developed and fully validated. Plasma concentration of EE rise to a peak of 128 pg/ml following the oral administration of 50 microgram EE. Following the intravenous administration of the same dose of EE, plasma concentrations of the steroid declined biexponentially, the two half-lives being 0.83 and 6.75 hours. Comparison of the results of the intravenous and oral administration of the steroid suggested that its oral bioavailability is 42%. Although EE thus has a lower bioavailability than norethindrone, the pharmacokinetics of the two steroids, as reflected by half-lives, plasma clearance and volume of distribution, are very similar. The occurrence of a secondary peak in plasma at around 12 hours after dosing gave strong evidence that EE undergoes enterohepatic circulation in women; an event that may have considerable clinical significance.

References

Mar 1, 1977·Journal of Reproduction and Fertility·J R PasqualiniF A Kincl
Sep 1, 1976·Contraception·K Fotherby, R J Warren

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Citations

Dec 1, 1991·Advances in Contraception : the Official Journal of the Society for the Advancement of Contraception·M Orme, D J Back
Jan 1, 1996·Contraception·A WeberA Balogh
Apr 1, 1981·Journal of Steroid Biochemistry·D J BackP H Rowe
May 1, 1981·Journal of Steroid Biochemistry·K FotherbyH Breuer
Mar 1, 1982·Journal of Steroid Biochemistry·D J BackE Thomas
Apr 1, 1983·Journal of Steroid Biochemistry·S M SimH J Eyssen
Jan 1, 1984·Journal of Steroid Biochemistry·H AdlercreutzJ T Korpela
Sep 1, 1988·Journal of Steroid Biochemistry·G M Pacifici, D J Back
Jan 1, 1989·Pharmacology & Therapeutics·M L OrmeS Ball
Sep 8, 1993·Journal of Chromatography·N FernándezM Sierra
Jun 1, 1991·The Journal of Steroid Biochemistry and Molecular Biology·K Fotherby
Apr 17, 2007·Contraception·Fang KejuanPeter Fajans
Sep 29, 1984·Lancet·M OrmeD H Jones
Dec 1, 1990·British Journal of Clinical Pharmacology·P CrawfordM Orme
Nov 1, 1992·Epilepsia·P Klosterskov JensenG P Menge
Jul 12, 1980·British Medical Journal
May 9, 1981·British Medical Journal·D J BackP H Rowe
Dec 5, 1981·British Medical Journal·M H Briggs
Jul 10, 2002·Clinical Pharmacokinetics·James W McAuley, Gail D Anderson
Jan 27, 2007·Clinical Pharmacokinetics·Hongjian ZhangA David Rodrigues
May 1, 1989·American Journal of Obstetrics and Gynecology·J W Goldzieher
Dec 1, 1990·American Journal of Obstetrics and Gynecology·M L Orme, D J Back
Dec 1, 1990·American Journal of Obstetrics and Gynecology·J P Hanker
May 1, 1986·Oral Surgery, Oral Medicine, and Oral Pathology·R Bainton

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