Ulipristal acetate: a new emergency contraceptive that is safe and more effective than levonorgestrel.

Ulipristal acetate (UPA), a selective progesterone receptor modulator, when taken as a single 30-mg dose, is safe and effective for emergency contraception up to 5 days (120 h) following unprotected intercourse. This indication has been approved in Europe since May 2009 and was approved by the US FDA in August 2010. The older progesterone-only emergency contraceptive, levonorgestrel (LNG), is approved only up to 72 h after unprotected intercourse. UPA is effective in delaying or inhibiting ovulation, even if taken 24 to 48 h prior to expected ovulation, a time when LNG is no longer effective. A recent meta-analysis of two randomized clinical trials showed UPA to have a pregnancy risk 42% lower than LNG up to 72 h, and 65% lower in the first 24 h following unprotected intercourse. In a randomized trial enrolling women up to 5 days after unprotected intercourse, significantly more pregnancies were prevented with UPA than with LNG when taken beyond 72 h.