Ulipristal acetate (CDB-2914) is an orally bioavailable, acetate salt of ulipristal, a selective progesterone receptor modulator with anti-progesterone activity. Ulipristal binds to the progesterone receptor (PR), thereby inhibiting PR-mediated gene expression, and interfering with progesterone activity in the reproductive system. As a result, this agent may suppress the growth of uterine leiomyomatosis. Furthermore, by inhibiting or delaying ovulation and effecting endometrial tissue, ulipristal can be used as an emergency contraception.

Ulipristal acetate抑制活化素A对成纤维细胞蛋白和血管内皮生长因子A（VEGF-A）mRNA在培养的子宫平滑肌细胞和子宫肌瘤细胞中的调控[2]。相较于对照组的精子，Ulipristal acetate在100-ng/mL剂量下减少了DNA的碎裂，并持续到10,000-ng/mL剂量[3]。

Ulipristal及CDB-4124在体内显示显著的抗孕酮活性[1]。Ulipristal acetate 可降低所有处理组大鼠乳腺纤维腺瘤和腺癌的发生率。大鼠在最高剂量下Ulipristal acetate暴露量[AUC(0-24h)]是人类每日10 mg治疗暴露量的67倍。在小鼠中，即使Ulipristal acetate暴露量高达治疗暴露的313倍，也未观察到任何类型肿瘤的增加。与Ulipristal acetate相关的小鼠发现仅限于肝脏、垂体、甲状腺/副甲状腺和附睾的器官重量变化，以及接受每日130 mg/kg剂量的雄性和雌性小鼠最小的全小叶性肝细胞肥大[4]。Ulipristal acetate（1 mg/kg及5 mg/kg）使病理学家评估子宫内膜厚度增加的频率与对照组相比以剂量依赖方式增加。随着Ulipristal acetate剂量的增加，分泌分化略有降低，亚核和超核空泡化的频率略有减少[5]。