Postcoital contraception, also known as emergency contraception, is currently based on a single 1.5 mg dose of levonorgestrel, a progestin, taken within 3 days after unprotected intercourse. However, efficacy appears to be similar when the drug is taken within 4 or 5 days. Ulipristal, a progesterone receptor agonist-antagonist, is now authorised in the European Union for postcoital contraception within 5 days after unprotected intercourse. Clinical evaluation of ulipristal in this setting is based on two trials versus levonorgestreland one non-comparative trial. One double-blind trial in 1672 women failed to show that ulipristal, taken within 3 days following intercourse, was any more effective than levonorgestrel. In another trial including 1893 women, ulipristal was not statistically more effective than levonorgestrel when the two drugs were taken within 5 days after intercourse. In a non-comparative trial in 1533 women who took ulipristalon the third, fourth or fifth day after intercourse, the pregnancy rate was 2.1%. This is lower than would be expected without contraception (about 5.5%) but an indirect comparison, providing only a low level of evidence, did not show superiority over levonorgestrel. Ulipristal, like levonorgestrel, can cause nausea and vomiting, and menstrual disorders. A few cases of ovarian cysts were observed with ulipristal, two of which required surgery. Co-administration of enzyme inducers may reduce the efficacy of both ulipristal and levonorgestrel. Little information is available on the risks incurred by the mother or child when ulipristal fails to terminate a pregnancy. As ulipristal has no proven advantages, postcoital contraception should continue to be based on levonorgestrel, a better-assessed drug. Levonorgestrel can be used up to 5 days after unprotected intercourse, even though it is only approved for use during the first 3 days.
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