Products
Ulipristal acetate was approved in the EU in 2009 and in the United States in 2010 (ellaOne, film-coated tablets). In many countries, ulipristal acetate was registered in late 2012. Since February 1, 2016, the morning-after pill has been available in pharmacies without a doctor’s prescription after a consultation and dispensing documentation (see also under levonorgestrel).
Structure and properties
Ulipristal acetate (C30H37NO4, Mr = 475.6 g/mol) exists as a white to yellow crystalline powder. The compound is structurally related to mifepristone and progesterone.
Effects
Ulipristal acetate (ATC G03AD02) inhibits or delays ovulation by suppressing the LH surge and thus may prevent unwanted pregnancy. Its effects are due to selective and high-affinity binding to the progesterone receptor, at which it exerts agonistic and antagonistic effects. Ulipristal acetate can be used for a longer period of time than levonorgestrel, which is only effective within 3 days (72 hours), according to the product information. Unlike levonorgestrel, ulipristal acetate is effective even immediately before ovulation, when the LH surge has already occurred. After the onset, however, it can no longer exert its effect. Ulipristal acetate is more effective than levonorgestrel in direct comparisons (e.g., Glasier et al., 2010).
Indications
For emergency contraception within 120 hours (5 days) of unprotected intercourse or contraceptive failure.
Dosage
According to the SmPC. The drug should be taken as soon as possible after unprotected sexual intercourse. It is a single dose. Administration is independent of meals, and the half-life is 32 hours. If vomiting occurs within 3 hours after taking the tablet, another tablet should be taken. Ulipristal acetate is intended for emergency use only. Until the next menstrual period, additional contraception should be used with a condom.
Contraindications
- Hypersensitivity
- Severe liver dysfunction
- Pregnancy
Full precautions can be found in the drug label.
Interactions
Ulipristal acetate is metabolized primarily by CYP3A4 and to a lesser extent by CYP1A2 and CYP2A6. Corresponding drug interactions with CYP inhibitors and CYP inducers are possible. Drugs that increase gastric pH, such as H2 antihistamines, antacids, and proton pump inhibitors, may reduce bioavailability. Furthermore, ulipristal acetate may reverse the effects of progestins, such as hormonal contraceptives.
Adverse effects
The most common possible adverse effects include headache, nausea, and abdominal and pelvic pain (dysmenorrhea). Rarely, severe liver damage can occur with regular use of Esmya containing the active ingredient ulipristal acetate for the treatment of fibroids. The drug was therefore withdrawn from the market for the time being in 2020. According to the European Medicines Agency, no such risk is known for the morning-after pill.
