Ulipristal acetate is a selective progesterone receptor modulator (SPRM) with tissue-selective partial antagonist activity. It has clinical use both as an emergency contraceptive and as a treatment for uterine fibroids. Ulipristal acetate acts as a partial antagonist on the hypothalamic–pituitary–ovarian axis to inhibit or delay ovulation without affecting human embryo implantation. As a progesterone antagonist, Ulipristal acetate selectively suppresses neo-vascularization, cell proliferation, and survival in uterine fibroid cells, but not in normal myometrial cells.
Ulipristal acetate is known to reduce uncontrolled bleeding due to post uterine fibroid surgery.