Ans. is d, i.e. Selective progesterone receptor modulatorRef: Harrison's Principles of Internal medicine 19th/ed, p2391Ulipristal acetate (trade name Ella One in the European Union, Ella in the US for contraception, and Esmya for uterine fibroid) is a selective progesterone receptor modulator (SPRM).PharmacodynamicsAs an SPRM, ulipristal acetate has partial agonistic as well as antagonistic effects on the progesterone receptor. It also binds to the glucocorticoid receptor, but is only a weak anti-glucocorticoid relative to mifepristone, and has no relevant affinity to the estrogen, androgen and mineralocorticoid receptors. Phase II clinical trials suggest that the mechanism might consist of blocking or delaying ovulation and of delaying the maturation of the endometrium.Medical Uses* Emergency contraception: For emergency contraception, a 30mg tablet is used within 120 hours (5 days) after an unprotected intercourse or contraceptive failure. It has been shown to prevent about 60% of expected, pregnancies, and prevents more pregnancies than emergency contraception with levonorgestrel.* Treatment of uterine fibroids: Ulipristal acetate is used for preoperative treatment of moderate to severe symptoms of uterine fibroids in adult women of reproductive age in a daily dose of a 5mg tablet. Treatment of uterine fibroids with ulipristal acetate for 13 weeks effectively controlled excessive bleeding due to uterine fibroids and reduced the size of the fibroids.InteractionsUlipristal acetate is metabolized by CYP3A4 in vitro. Ulipristal acetate is likely to interact with substrates of CYP3A4, like rifampicin, phenytoin, St John's wort, carbamazepine or ritonavir. Therefore, concomitant use with these agents is not recommended. It might also interact with hormonal contraceptives and progestogens such as levonorgestrel and other substrates of the progesterone receptor, as well as with glucocorticoids.Adverse EffectsCommon side effects include abdominal pain and temporary menstrual irregularity or disruption. Headache and nausea were observed under long-term administration (12 weeks), but not after a single dose.ContraindicationsUlipristal acetate should not be taken by women with severe liver diseases because of its CYP-mediated metabolism. It has not been studied in women under the age of 18.Pregnancy: Unlike levonorgestrel, and like mifepristone, ulipristal acetate is embryotoxic in animal studies. Before taking the drug, a pregnancy must be excluded.