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Mifepristone molecular structure

The drug mifepristone (RU486, RU38486; ZK98296) is a progesterone receptor antagonist similar in structure to the natural hormone progesterone. This drug is used medically as a birth control drug.

Progesterone is a steroidal hormone of the progestogens class, which has many roles in the female. Functions include regulation of the menstrual cycle, uterine changes, maintaining pregnancy and effects on systems throughout the body. Biological sources include: adrenal glands, gonads (corpus luteum), brain, and placenta.

Male progesterone has a suggested role in neural development. Progesterone is also used clinically as a part of hormone replacement therapy (HRT) in women. The human progesterone receptor has two isoforms (PRA and PRB).

Commercial drug names include Mifegyne and Mifeprex.

Links: menstrual cycle | progesterone | ectopic pregnancy

Some Recent Findings

  • Medical abortion: it is time to lift restrictions[1] "Lifting the special drug status applied to medical abortion medications will enable equitable access. In 2016, the Committee on Economic, Social and Cultural Rights (a collection of human rights experts tasked with interpreting these rights), in its groundbreaking interpretation of the right to sexual and reproductive health, asserted that abortion services are an integral part of the right to health....Professor Caroline de Costa, professor of Obstetrics and Gynaecology at James Cook University in Cairns, and colleagues wrote that availability of mifepristone was blocked from 1996 to 2006 when Senator Brian Harradine’s amendment to the Therapeutic Goods Act of 1989 was supported by then Prime Minister John Howard in exchange for Harradine’s support for the privatisation of Telstra." MJA Article MJA Editorial
  • Mifepristone Prevents Stress-Induced Apoptosis in Newborn Neurons[2] "Forced swimming induced selective apoptotic cell death in 1 week-old cells, an effect that was abolished by pretreatment with mifepristone. Independent of its antagonism of GR, mifepristone also induced an increase in the percentage of 1 week-old cells that were AMPA(+). We propose that the induction of AMPA receptor expression in immature cells may mediate the neuroprotective effects of mifepristone, in line with the proposed antidepressant effects of AMPA receptor potentiators."
More recent papers  
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This table allows an automated computer search of the external PubMed database using the listed "Search term" text link.

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  • The displayed list of references do not reflect any editorial selection of material based on content or relevance.
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Search term: Mifepristone

Older papers  
These papers originally appeared in the Some Recent Findings table, but as that list grew in length have now been shuffled down to this collapsible table.

See also the Discussion Page for other references listed by year and References on this current page.

  • Comparing two early medical abortion regimens: mifepristone+misoprostol vs. misoprostol alone[3] "Mifepristone+misoprostol is significantly more effective than use of misoprostol-alone for early medical abortion. The number of ongoing pregnancies documented with misoprostol-only warranted an early end of the trial after unblinding of the study at interim analysis. Policymakers should advocate for greater access to mifepristone. Future research should prioritize misoprostol-only regimens with shorter dosing intervals."


Model mifepristone bound to progesterone receptor.[4]

A progesterone receptor antagonist.

  • Progesterone normally binds to the progesterone receptor and generates a receptor conformational change allowing it to then bind to DNA and act as a transcription factor for genes.
  • Mifepristone binds the same progesterone receptor with 10-fold higher affinity. It binds to the C-terminal region of the hormone-binding domain and then does not act as a transcription factor.

Also binds to the glucocorticoid receptor (GR) and weakly to the androgen receptor.


A new chemical and pharmacological analog of mifepristone, acting as a selective progesterone receptor modulator. Currently identified as a second generation emergency contraceptive.

  • trade name - ella® (Laboratoire HRA Pharma, Paris, France)



The drug methotrexate (MTX, amethopterin) is a folic acid antagonist and is used clinically as a chemotherapy agent (cancer), immune system suppressant (autoimmune diseases), treating treating rheumatoid arthritis[5] and for medical abortions with ectopic pregnancy[6].

Links: folic acid | Abnormal_Development_-_Ectopic_Implantation#Methotrexate Ectopic Pregnancy | ectopic implantation | Medline Plus | PubChem



  1. de Costa CM, Black KI & Russell DB. (2019). Medical abortion: it is time to lift restrictions. Med. J. Aust. , 210, 248-249.e1. PMID: 30861138 DOI.
  2. Llorens-Martín M & Trejo JL. (2011). Mifepristone prevents stress-induced apoptosis in newborn neurons and increases AMPA receptor expression in the dentate gyrus of C57/BL6 mice. PLoS ONE , 6, e28376. PMID: 22140582 DOI.
  3. Ngoc NT, Blum J, Raghavan S, Nga NT, Dabash R, Diop A & Winikoff B. (2011). Comparing two early medical abortion regimens: mifepristone+misoprostol vs. misoprostol alone. Contraception , 83, 410-7. PMID: 21477682 DOI.
  4. Raaijmakers HC, Versteegh JE & Uitdehaag JC. (2009). The X-ray structure of RU486 bound to the progesterone receptor in a destabilized agonistic conformation. J. Biol. Chem. , 284, 19572-9. PMID: 19372222 DOI.
  5. Lopez-Olivo MA, Siddhanamatha HR, Shea B, Tugwell P, Wells GA & Suarez-Almazor ME. (2014). Methotrexate for treating rheumatoid arthritis. Cochrane Database Syst Rev , , CD000957. PMID: 24916606 DOI.
  6. Marret H, Fauconnier A, Dubernard G, Misme H, Lagarce L, Lesavre M, Fernandez H, Mimoun C, Tourette C, Curinier S, Rabishong B & Agostini A. (2016). Overview and guidelines of off-label use of methotrexate in ectopic pregnancy: report by CNGOF. Eur. J. Obstet. Gynecol. Reprod. Biol. , 205, 105-9. PMID: 27572300 DOI.


Kulier R, Kapp N, Gülmezoglu AM, Hofmeyr GJ, Cheng L & Campana A. (2011). Medical methods for first trimester abortion. Cochrane Database Syst Rev , , CD002855. PMID: 22071804 DOI.

Spitz IM. (2010). Mifepristone: where do we come from and where are we going? Clinical development over a quarter of a century. Contraception , 82, 442-52. PMID: 20933118 DOI.

Im A & Appleman LJ. (2010). Mifepristone: pharmacology and clinical impact in reproductive medicine, endocrinology and oncology. Expert Opin Pharmacother , 11, 481-8. PMID: 20102310 DOI.

Schaff EA. (2010). Mifepristone: ten years later. Contraception , 81, 1-7. PMID: 20004266 DOI.

Gemzell-Danielsson K & Marions L. (2004). Mechanisms of action of mifepristone and levonorgestrel when used for emergency contraception. Hum. Reprod. Update , 10, 341-8. PMID: 15192056 DOI.



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Cite this page: Hill, M.A. (2024, February 26) Embryology Mifepristone. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Mifepristone

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G