Mifepristone (RU486) is a progesterone receptor antagonist (antiprogesterone) which can prevent between 92-100% of pregnancies on oral intake of a 10-600 mg dose within 72 h of unprotected intercourse. Mifepristone is used in several countries (Europe, Russia, India, China, New Zealand) and was approved for use in the USA in September of 2000. (Alternative commercial names: Mifegyne, Mifeprex)
Commercial Mifepristone Pills
Recently the drug RU486, which is an abortive rather contraceptive drug, has been the centre of political and medical discussions in Australia. Currently (Feb 2006) the Senate is holding an inquiry, not into the effacacy of RU486, but into who should be responsibile for approval in Australia (the Health minister or Therapeutic Goods Administration). (More? Australian Senate Inquiry)
Page Links: Introduction | Mifepristone and Progesterone Structure | Australian Senate Inquiry | Simplified Medical Abortion Regimen | NCBI Bookshelf | References | Glossary WWW Links
Below are shown chemical structures for both mifepristone and progesterone.
Mifepristone
Recently the drug RU486, which is an abortive rather contraceptive drug, has been the centre of political and medical discussions in Australia. Currently (Feb 2006) the Senate is holding an Inquiry into Therapeutic Goods Amendment (Repeal of Ministerial responsibility for approval of RU486) Bill 2005
"1.8 The Committee acknowledged that in accordance with Senate procedures the inquiry should be restricted to the stated purpose of the Bill, which is to remove the responsibility for approval of RU486 from the Minister and to provide responsibility for approval of RU486 to the Therapeutic Goods Administration."
"1.13 The explanatory memorandum describes the current approval process for RU486 and the change that is proposed by the Bill: In 1996 amendments to the Therapeutic Goods Act were passed that placed medications such as RU486 in a special group of drugs known as ’restricted goods’. According to the 1996 amendments restricted goods cannot be evaluated, registered, listed or imported without the written approval of the Minister for Health and Ageing. In addition, any such written approval must be laid before each House of the Parliament by the Minister within 5 sitting days of being given. RU486 is the only medicine that is subject to the restricted goods condition. Medicines used for any purpose other than abortion are evaluated and regulated by the Therapeutic Goods Administration (TGA) alone and do not require additional approval from the Minister for Health and Ageing... Removal of the restricted goods provisions in the Act would mean that RU486 could be evaluated within the same framework as applies to all other medicines." (modified extracts from the Senate report) (More? Senate Committee Inquiry | Information relating to the reference | Public Hearings and Transcripts | Report Feb 2006 (PDF 592 KB))
"Under the usual procedure for mifepristone-misoprostol abortion, a woman with a pregnancy duration of 49 days or less takes 600 milligrams of mifepristone, in the form of three pills, at a clinic. Mifepristone blocks progesterone, a hormone that helps maintain pregnancy. The woman returns to the clinic 48 hours later to take 400 micrograms of misoprostol orally, which causes her uterus to contract and helps to complete the abortion. Approximately two weeks later, the woman again returns to the clinic to confirm that her pregnancy has ended." (text from Population Council Population Briefs June 2001, Vol. 7, No. 2)
NCBI Bookshelf
Clinical Methods (3rd edition) Walker, H.K.; Hall, W.D.; Hurst, J.W.; editors Stoneham (MA): Butterworth Publishers; c1990 174. Birth Control | table 174.1. First-year Failure Rates of Birth Control Methods
Health, United States, 2004 Atlanta (GA): Centers for Disease Control and Prevention; 2004 table 17. Contraceptive use among women 15-44 years of age (USA)
Reviews
Sarkar NN. The potential of mifepristone (RU-486) as an emergency contraceptive drug. Acta Obstet Gynecol Scand. 2005 Apr;84(4):309-16. Review.
Bongaarts J, Johansson E. Future trends in contraceptive prevalence and method mix in the developing world.
Articles
Vervest HA, Haspels AA. Preliminary results with the antiprogestational compound RU-486 (mifepristone) for interruption of early pregnancy. Fertil Steril. 1985 Nov;44(5):627-32.
Couzinet B, Le Strat N, Ulmann A, Baulieu EE, Schaison G. Termination of early pregnancy by the progesterone antagonist RU 486 (Mifepristone). N Engl J Med. 1986 Dec 18;315(25):1565-70.
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Discussing birth control in relation to the Human Menstrual Cycle raises many different issues (social, ethical, political, religious) associated with this topic. Please note that only the embryological and biological issues are covered here.
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