Mifepristone Cas:84371-65-3

Mifepristone has a steroid structure and is a new anti-progesterone drug with anti-glucocorticoid activity but no progesterone, androgen, estrogen and anti-estrogen activity. At the molecular level, it is competitive with endogenous progesterone to bind receptors, thus producing strong anti-progesterone effect, denaturating decidua and villi tissues of pregnancy, releasing endogenous prostaglandins, promoting LH decline and luteolysis

Mifepristone is also known as anti-progesterone, Sibex, Siyan, containing bead, Smian, minasterone, belongs to anti-progesterone drugs, is a French Roussel-Uolsf company in the early 1980s first developed a new type of anti-fertility drugs acting on the receptor level, no progesterone, androgen, estrogen activity, 1988 in France for the first time on the market. It mainly acts on the endometrial progesterone receptor, can bind to the progesterone receptor and glucocorticoid receptor, has a high affinity, and the affinity for the endometrial progesterone receptor is 5 times stronger than that of progesterone, has no obvious effect on the cortisol level under effective dose, can produce strong anti-progesterone effect, and cause the deciduum and chorionic tissue degeneration of pregnancy, and the release of endogenous prostaglandin. Lead to uterine contraction, at the same time can reduce the production of human chorionic gonadotropin, luteolysis, so that the embryo abortion. Because the drug can not cause enough uterine activity, the rate of incomplete abortion is high when it is used only for anti-early pregnancy, but it can increase the sensitivity of the uterus to prostaglandin, so the addition of small doses of prostaglandin can reduce the adverse reaction of prostaglandin, and can significantly increase the rate of complete abortion. In addition, Mifepristone also has the effect of softening and dilating the cervix.

Biological activity and mechanism of action
Mifepristone has strong anti-progesterone activity. Animal experiments show that the binding force of Mifepristone to progesterone receptor is 3 ~ 5 times higher than that of progesterone. Mifepristone mainly acts on the endometrium, and competes with endogenous progesterone to bind receptors at the molecular level, producing strong anti-progesterone effects, and produces the following physiological activities:
1. Competitive occupation of progesterone receptors in decidua leads to withdrawal of progesterone action, degeneration and necrosis of decidua tissues, secondary damage and dissection of villi, resulting in decreased HCG level and luteolysis. The mechanism is that Mifepristone can directly act on the syncytic cell trophoblast, causing a dose-dependent decrease in the production rate of HCG, HPL and P.
2, promote the release of endogenous prostaglandins, resulting in uterine contraction.
3. At the same time, it also acts on the anterior hypothalamic pituitary, promoting the decline of FSH and LH, and the luteolysis, thus making the pregnancy dependent on the maintenance of the luteum fail, resulting in abortion.
4. It acts on the cervix to soften and expand, which is conducive to the discharge of embryo sac and decidua.