Selective progesterone receptor modulators: Mechanisms of action and possible clinical applications

Background: Selective progesterone receptor modulators (SPRM) are a group of substances with a multitude of potential applications in the field of gynecological endocrinology. Material and methods: The state of knowledge on the mechanisms of action of SPRMs is summarized based on the currently available literature. In addition, the possible indications are discussed. Results: The effects of progesterone are mediated by progesterone receptors (PR) and SPRMs have agonistic as well as antagonistic effects on the isoforms of PR. The isoforms primarily function as ligand-activated transcription factors. Possible indications are contraception, postcoital contraception, endometriosis therapy and treatment of uterine leiomyomas. Currently approved for clinical use are ulipristal acetate (UPA) and mifepristone (MFP), which can be prescribed as an effective postcoital contraceptive but the exact mechanism of action is not yet fully clarified. Additionally, UPA is a therapy option for premenopausal women with symptomatic uterine leiomyomas. There has been relatively little progress in the development of SPRMs for contraception. So far the amount of data currently available on the indications in the sense of long-term contraception are scarce. Conclusion: The main fields of application of SPRMs are postcoital contraception and preoperative treatment of uterine leiomyomas. Future research efforts concerning the use of SPRMs are currently centered on the field of long-term contraception. Of particular interest is the vaginal ring delivery of UPA. © 2015, Springer-Verlag Berlin Heidelberg.