[Antiprogestins].

In a survey it is reported on the antiprogestins mifepristone (RU 486) and gestrinone (R 2323). Thanks to its high reversible affinity for progesterone receptor mifepristone stops progesterone activity at its target organs. Mifepristone also inhibits ovarian progesterone synthesis. This antiprogesterone was tested clinically with different results for following indications: postcoital contraception, luteolysis, early abortion, ectopic pregnancy, missed abortion, cervix priming, and breast cancer. Gestrinone has antiestrogenic, antiprogesterone, and weak androgenic properties. These effects are related to the affinity for estrogene-, progesterone- and androgene receptor. A suppressory action on gonadotropins has been observed in therapeutic dosages. On the basis of its properties gestrinone is used for treatment of endometriosis, leiomyomas, benign breast diseases and also for contraception.