Since the discovery of the progesterone receptor antagonist mifepristone, numerous additional compounds, which display a spectrum of biological actions ranging from full antagonist to those with mixed agonist/antagonist activity, have been synthesized. The latter are referred to as selective progesterone receptor modulators. Long-term administration of these agents is associated with an antiproliferative action on the endometrium as well as amenorrhea and often inhibition of ovulation. Thus far, the majority of clinical data have been obtained with mifepristone but studies are currently underway with other compounds. These compounds have application in the treatment of uterine myoma, endometriosis, dysfunctional uterine bleeding, as potential contraceptives and in steroid responsive tumors.
