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Effective alternative for emergency contraception

New drug highly effective and licensed for use up to five days after unprotected sex

OnMedica Staff

Friday, 29 January 2010

Ulipristal acetate is a newly licensed drug that provides an effective method of emergency contraception when taken up to five days after unprotected intercourse, reports research published in The Lancet Online First today. By contrast, levonorgestrel (Levonelle/Levonelle One Step) is licensed to be taken up to 72 hours after unprotected sex.

Researchers conducted their own randomised non-inferiority trial comparing ulipristal acetate with levonorgestrel for emergency contraception, and also a meta-analysis combining their results with those of a previous study.

Women who requested emergency contraception from a participating family planning clinic in the UK, Ireland and the US within five days of unprotected sex, and who had regular menstrual cycles, were eligible for the study. They were randomised to receive either a single dose of 30mg ulipristal acetate (1104 women) or to take 1.5mg levonorgestrel (1117 women).

Women were followed up 5-7 days after the due date of their next menstrual period and, if menses had not begun by then, again a week later and beyond.

The primary endpoint was the rate of pregnancy in women who had taken emergency contraception within 72 hours of unprotected intercourse. The rate in women who had received emergency contraception within 120 hours was analysed as a secondary endpoint.

The study authors combined the data from their own trial with those from the only previous head-to-head trial of ulipristal acetate and levonorgestrel, to increase statistical power and provide better generalisability of the results.

Among women who took emergency contraception within 72 hours of sexual intercourse, 1.8% became pregnant in the ulipristal acetate group and 2.6% in the levonorgestrel group.

Ulipristal acetate almost halved the risk of becoming pregnant compared with levonorgestrel in women who took the drugs within five days (120 hours) after sexual intercourse. When emergency contraception was taken within 24 hours of unprotected sex (as it was for a third of the women in this study), the risk of pregnancy was almost two-thirds lower with ulipristal acetate than it was with levonorgestrel.

Adverse events occurred at a similar rate in both groups; the most common was headache, reported by 19.3% of women who had taken ulipristal acetate and 18.9% of those who had taken levonorgestrel.

The authors say that because levonorgestrel is available without prescription following its safe use by millions of women, it is likely to remain more easily accessible than ulipristal acetate until there are more safety data for the new drug.

However, they point out: “Despite the issues around health-care service delivery, ulipristal acetate provides women and health-care providers with an alternative choice for emergency contraception that can be used up to five days after unprotected sexual intercourse.”

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