Ulipristal acetate: contraceptive or contragestive?
Keenan, J.A.
Annals of PharmacoTherapy 45(6): 813-815
2011
ISSN/ISBN: 1542-6270 PMID: 21666088 DOI: 10.1345/aph.1q248Document Number: 221577
Ulipristal acetate is the first selective progesterone receptor modulator approved for postcoital contraception in the US. It appears to be significantly more effective in inhibition of ovulation than other forms of emergency contraception. However, ulipristal acetate is structurally similar to mifepristone, and several lines of evidence suggest that a postfertilization mechanism of action is also operative. This mechanism of action is considered to be contragestive versus contraceptive. Ulipristal acetate administration is contraindicated in a known or suspected pregnancy; however, it could quite possibly be used as an effective abortifacient. Health-care providers should inform patients of the possibility of both mechanisms of action with use of this drug.