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A novel emergency contraceptive is effective and well tolerated up to 120 hours after unprotected sexual intercourse, researchers said.

The finding makes ulipristal acetate the first emergency contraceptive to be effective for such a long period of time, according to Paul Fine, MD, of Planned Parenthood of Houston & Southeast Texas, and colleagues. They reported their findings in the February issue of Obstetrics & Gynecology.

The only FDA-approved similar medication is Teva's levonorgestrel (Plan B One-Step), which is indicated for use up to 72 hours after unprotected sex.

Ulipristal is manufactured by HRA Pharma of Paris, which supported the study. Ulipristal has been given marketing authorization in Europe (under the brand name ellaOne) but is not yet approved in the U.S.

Currently, the options for women needing emergency contraception more than 72 hours after intercourse are limited to copper intrauterine devices, which have been shown to be highly effective, the researchers noted in the journal.

But such devices are not universally available, can be inserted only by a trained clinician, and have a risk of complications including perforation of the uterus.

Ulipristal, a selective progesterone receptor modulator that blocks or delays ovulation, has been shown to be as efficacious as levonorgestrel when used in the first 72 hours after unprotected intercourse, Fine and colleagues said.

To see how well it would do outside that time window, the researchers studied 1,241 women 18 or older with regular cycles who sought emergency contraception between 48 and 120 hours after unprotected intercourse.

They were treated with a single 30-milligram dose of ulipristal and their subsequent pregnancy status was discovered by urinary human chorionic gonadotropin testing, as well as return of menses, Fine and colleagues said.

To be a success, the researchers said, the trial had to yield a pregnancy rate less than the expected 5.5% and an upper bound of the 95% confidence interval less than a so-called "threshold of irrelevance" of 4%.

Overall, they reported, 26 of the women were found to be pregnant -- a rate of 2.1%, with a 95% confidence interval from 1.4% to 3.1%, which met both objectives.

Unlike levonorgestrel, they said, the efficacy did not decrease significantly over time, they said. Specifically, pregnancy rates were:

• 2.3% (with a 95% confidence interval from 1.4% to 3.8%) when the treatment was given between 48 and 72 hours after unprotected sex
• 2.1% (with a 95% confidence interval from 1.0% to 4.1%) when the delay was between 72 and 96 hours
• 1.3% (with a 95% confidence interval from 0.1% to 4.8%) between 96 and 120 hours

Fine and colleagues said the most frequent adverse events were headache, nausea, and abdominal pain, but they were mostly mild or moderate and resolved spontaneously.

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