Major Finding: The risk of pregnancy was 0.9% with ulipristal vs. 2.5% with levonorgestrel when women presented within 24 hours after unprotected intercourse.
Data Source: A multisite study of 1,899 women who presented at family planning clinics requesting emergency contraception.
Disclosures: Funded by HRA Pharma, the manufacturer of ulipristal. Three investigators report having received lecture honoraria from HRA Pharma. Three are current employees of HRA Pharma, one is a former employee and a stockholder, another reports having received consulting fees from HRA, and five report no conflicts of interest.
The investigational drug ulipristal acetate is more effective than the widely used levonorgestrel in preventing pregnancy at any point within 5 days of unprotected intercourse.
Researchers led by Dr. Anna F. Glasier of the National Health Service in Edinburgh performed their own study of nearly 2,000 women in Europe and the United States and also analyzed findings from a previous study.
Though neither study was of sufficient size to demonstrate the superiority of ulipristal over levonorgestrel, Dr. Glasier and her colleagues wrote, combining the data from both studies showed that ulipristal “almost halved the risk of becoming pregnant compared to levonorgestrel in women who received emergency contraception within 120 hours” (1.3% vs. 2.2%). The risk was reduced by nearly two-thirds when women presented within 24 hours (0.9% vs. 2.5%), the investigators wrote.
“Only when we put the two studies together were we able to demonstrate superiority,” said Dr. Glasier in an interview.
In the multisite study, 1,899 women who presented requesting emergency contraception at family planning clinics in the United Kingdom, Ireland, and the United States were assigned to a single dose of either ulipristal 30 mg (n= 941) or levonorgestrel 1.5 mg (n= 958) (Lancet 2010 [doi:10.1016/S0140-6736(10)60101-8
Ulipristal is manufactured by HRA Pharma, which funded the study. Levonorgestrel is made by Shering.
Of the 1,696 women who had presented within 72 hours of intercourse, there were 15 pregnancies in the ulipristal group (1.8% of 844 women) and 22 in the levonorgestrel group (2.6 % of 852).
Among the 203 women who received emergency contraception after 72 hours, there were three pregnancies, all in the levonorgestrel group.
Patients ranged in age from 16 years to over 35; they were not told which drug they had received. Follow-up with pregnancy testing began within a week after the expected onset of next menses.
The 1,899 women in the analyzed group were those remaining from a total 2,221 who had presented to the family planning clinics.
Excluded from study were those who were older than 35, who were lost to follow-up, who were pregnant when presenting, who re-enrolled in the study, or whose pregnancy status was unknown following treatment.
The authors also analyzed findings from a 2006 randomized controlled trial comparing ulipristal to levonorgestrel in 1,546 efficacy-evaluable women, all of whom had presented within 72 hours of intercourse (Obstet Gynecol 2006;108:1089-97). There, too, the pregnancy rate was lower for ulipristal—7 pregnancies out of 773 patients (0.9%) and 13 out of 773 (1.7%) for levonorgestrel.
The European Medicines Agency approved ulipristal in May 2009 for preventing pregnancy up to 120 hours after intercourse. It is not currently approved in the United States.
Levonorgestrel is approved in both the United States and in the European Union for use up to 72 hours after intercourse.