Mifepristone

Embryology - 26 Jun 2024 Expand to Translate
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Introduction

Mifepristone molecular structure

(RU 486) A progesterone receptor antagonist similar in structure to the natural hormone progesterone, which 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

Some Recent Findings

Mifepristone Prevents Stress-Induced Apoptosis in Newborn Neurons ^[1] "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."
Comparing two early medical abortion regimens: mifepristone+misoprostol vs. misoprostol alone^[2] "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."

More recent papers
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Function

Model mifepristone bound to progesterone receptor.^[3]

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.

Ulipristal

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