Ulipristal acetate, sold under the brand name Ella among others, is a medication used for emergency contraception (birth control) and uterine fibroids. As emergency contraception it should be used within 120 hours of vaginally penetrating intercourse. For fibroids it may be taken for up to six months. It is taken by mouth.Common side effects include headache, nausea, feeling tired, and abdominal pain. It should not be used in women who are already pregnant. It is in the selective progesterone receptor modulator (SPRM) class of medications. It works by preventing the effects of progesterone, therefore preventing ovulation but not affecting fertilization or implantation.Ulipristal acetate was approved for medical use in the United States in 2010. It is on the World Health Organizations List of Essential Medicines. Medical uses
Emergency contraception
For emergency contraception a 30 mg tablet is used within 120 hours (5 days) after unprotected intercourse or contraceptive failure. It has been shown to prevent about 62–85% of expected pregnancies, and prevents more pregnancies than emergency contraception with levonorgestrel. Ulipristal acetate is available by prescription for emergency contraception in over 50 countries, with access through pharmacists without a prescription being tested in the United Kingdom. In November 2014, the European Medicines Agency (EMA) recommended availability of ellaOne emergency contraceptive without prescription in the European Union. In January 2015 the European Commission issued an implementing decision amending accordingly the marketing authorization of EllaOne in the EU. Since July 2016, it is available without prescription in Israel.
It is unlikely that ulipristal acetate could effectively be used as an abortifacient, since it is used in much lower doses (30 mg) than the roughly equipotent mifepristone (600 mg), and since mifepristone has to be combined with a prostaglandin for the induction of abortion. However, data on embryotoxicity in humans are very limited, and it is not clear what the risk for an abortion or for teratogenicity (birth defects) is. Of the 29 women studied who became pregnant despite taking ulipristal acetate, 16 had induced abortions, six had spontaneous abortions, six continued the pregnancies, and one was lost to follow-up. Lactation
It is not recommended to breast feed within seven days of taking the drug since ulipristal acetate is excreted into the breast milk, and possible effects on the infant have not been studied. Side effects
The most common side effects include headache, nausea (feeling sick), abdominal pain (stomach ache), and dysmenorrhea (period pains). Interactions
Ulipristal acetate is metabolized by CYP3A4 in vitro. Ulipristal acetate is likely to interact with substrates of CYP3A4, like rifampicin, phenytoin, St Johns 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. Pharmacology
Pharmacodynamics
As an SPRM, ulipristal acetate has partial agonistic as well as antagonistic effects on the progesterone receptor. Ulipristal acetate exhibits similar potency to antagonize progesterone receptor as mifepristone in vitro.