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« on: May 25, 2010, 08:28:35 pm » |
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Ulipristal acetate (UA) provides an effective alternative to the widely-used emergency contraception drug levonorgestrel and prevents more pregnancies, according to recently published research.
Researchers found that UA, a selective progesterone-receptor modulator, was effective for up to 5 days after unprotected sexual intercourse. Levonorgestrel, on the other hand, shows only limited evidence that the drug is effective beyond the third day. [Lancet 2010 Feb 13;375(9714):555-62]
“For women who presented on the fourth or fifth day after sexual intercourse in our trial, ulipristal acetate provided significant prevention of pregnancy whereas levonorgestrel did not, and, unlike levonorgestrel, ulipristal acetate is licensed for use beyond 72 [hours] and up to 120 [hours],” conclude the authors.
Compared to levonorgestrel, UA almost halved the risk of becoming pregnant (OR 0.55, 95% CI 0.32-0.93) and reduced the risk of pregnancy by almost two-thirds when used within 24 hours (OR 0.35, 95% CI 0.11-0.93).
More unwanted pregnancies could be prevented through an orally active method such as UA that is more effective than levonorgestrel and works irrespective of the time of sexual intercourse in the menstrual cycle. Indeed, it is the ability of UA to inhibit ovulation even when given just before ovulation which the researchers identify as being particularly important – explaining that this is the time of a woman’s menstrual cycle when “the probability of conception is at its peak and the frequency of sexual intercourse is at its highest.”
But unlike levonorgestrel, which has been safely taken by millions of women worldwide and is therefore often available without prescription, UA requires administration via a pharmacy or nurse – at least until further safety data becomes available. Despite this, say the study authors,
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