Progesterone receptor antagonists and selective progesterone receptor modulators: proven and potential clinical applications

Abstract

Progesterone receptor antagonists (PAs) and selective progesterone receptor modulators (SPRMs) are members of the progesterone receptor ligand family. The PA mifepristone is usually used as a single dose for short-term indications, such as pregnancy termination, cervical dilation, fetal death and emergency contraception. In view of their antiproliferative effect on the endometrium and their ability to produce amenorrhea, both PAs and SPRMs may be used long term in the treatment of uterine myoma and endometriosis. They may also have applications in dysfunctional uterine bleeding, breast and ovarian carcinoma, contraception and, possibly, in postmenopausal women as a form of estrogen-free replacement therapy. Despite the endometrial antiproliferative effect, during long-term administration of these drugs some women have developed endometrial thickening on ultrasound. This may be interpreted as endometrial hyperplasia, although experienced pathologists have doubted whether this is true hyperplasia.