Progesterone antagonists
Mifepristone called RU 486 is a structural analogue of progesterone and a competitive antagonist of progesterone. It has, moreover, an anti-glucocorticoid action and decreases the effects of cortisol.
Progesterone is essential to the maintenance of pregnancy and its ovarian secretion is increased rapidly after fecundation. The administration of mifepristone at the beginning of pregnancy induces abortion. It is used for medical termination of pregnancy. To reinforce the abortive action of mifepristone, it is combined with prostaglandins such as gemeprost or sulprostone which induce uterine contractions. In event of failure of termination of pregnancy, the risk of malformation of the fetus could be increased.
Mifepristone could be used to elicit labor when pregnancy is going beyond term.
Uterine bleeding is one of the adverse effects of mifepristone.
|
