Ulipristal Acetate Works Up to Five Days as "Morning After" Pill
Ulipristal acetate has been found to be as effective as levonorgestrel (Plan B One Step) for use in emergency contraception when taken within three days of unprotected intercourse. Ulipristal acetate is even more effective than Plan B when taken up to 5 days (120 hours) after intercourse.
Anna Glasier, DSc, MD and colleagues have published the results of their randomized, multicenter, single-blind study online in The Lancet. They compared the efficacy and safety of ulipristal acetate with levonorgestrel for emergency contraception.
The study enrolled 2,221 women with regular menstrual cycles who came to one of 35 participating family planning clinics, requesting emergency contraception within five days after unprotected intercourse. These women where then randomly assigned to receive a single dose of 30 mg ulipristal acetate (n=1104) or 1·5 mg levonorgestrel (n=1117) orally.
Participants were masked to treatment assignment whereas investigators were not. Follow-up was done 5—7 days after expected onset of next menses. The primary endpoint was pregnancy rate in women who received emergency contraception within 72 h of unprotected sexual intercourse.
Analysis excluded women lost to follow-up, those over 35, women with unknown follow-up pregnancy status, and those who had re-enrolled in the study. This left a total of 1,696 participants (ulipristal acetate, n=844; levonorgestrel, n=852) .
There were a total of 37 pregnancies: 15 pregnancies in the ulipristal acetate group (1.8%) and 22 in the levonorgestrel group (2.6%).
There were 203 women who received emergency contraception between 72 h and 120 h after sexual intercourse. In this group there were three pregnancies, all of which were in the levonorgestrel group.
The most frequent adverse event was headache: ulipristal acetate, 213 events in 1104 women (19.3%); levonorgestrel, 211 events in 1117 women(18.9%). There were two serious adverse events which the researchers judged possibly related to use of emergency contraception; a case of dizziness in the ulipristal acetate group and a molar pregnancy in the levonorgestrel group.
The researchers cautioned that the findings might not generalize to all groups of women. Women on hormonal contraception were excluded from the study, but emergency contraception is often used to treat women who have missed oral contraceptive pills, they noted.
Ulipristal is made 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 United States. Levonorgestrel is marketed here as Plan B One-Step.
Glasier AF, et al "Ulipristal acetate versus levonorgestrel for emergency contraception: a randomised non-inferiority trial and meta-analysis" Lancet 2010; DOI: 10.1016/S0140-6736(10)60101-8.