Mechanisms of action of hormonal emergency contraceptives

Pharmacotherapy
Vivian W Y LeungJudith A Soon

Abstract

Hormonal emergency contraceptives have been used to prevent unwanted pregnancy for more than 3 decades. The mechanisms of action of the regimen containing a combination of estrogen and progestin, known as the Yuzpe regimen, and those of the levonorgestrel regimen continue to be controversial, especially over the possibility that these regimens might act by interfering with implantation of the fertilized ovum. We performed a search of the PubMed (1949-July 2009) and EMBASE (1980-July 2009) databases to identify literature on the mechanisms of action of these contraceptive regimens, and data were extracted from pertinent English-language studies. We classified studies according to the approach taken by the investigators to study the actions of emergency contraceptives on pregnancy: an indirect method that uses statistical models to determine whether emergency contraceptives would be as effective as reported if they act only by disrupting ovulation; direct observation of the effects of emergency contraceptives on surrogate outcomes, including ovulation, sperm activity, hormonal levels, and endometrial receptivity to implantation; and analysis of directly observed pregnancy outcomes against statistical data. Acceptability of emerge...Continue Reading

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Citations

Aug 29, 2012·Journal of Forensic Nursing·Nikole K FerreeLarry Cahill
Jun 22, 2013·American Journal of Pharmaceutical Education·Shardae YoungKathleen Vest
Nov 26, 2011·Expert Review of Clinical Pharmacology·Jade L Sullivan, Marilyn N Bulloch
Mar 15, 2012·Molecular and Cellular Endocrinology·Nathalie Chabbert-BuffetPhilippe Bouchard
Nov 10, 2011·Contraception·Cristina Lopez-del BurgoJokin de Irala
Jan 18, 2011·Contraception·Crisitina Lopez-del BurgoJoseph B Stanford
Sep 24, 2019·Nigerian Medical Journal : Journal of the Nigeria Medical Association·Monalisha SahuVaishali Gautam
May 5, 2015·Fertility Research and Practice·Waleed M SweilehAnsam F Sawalha
Apr 21, 2021·The International Journal of Pharmacy Practice·Clare MaxwellValerie Fleming

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