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Emergency contraceptive pills in Canada

Therapeutics Initiative (University of British Columbia)

Background: Two emergency contraceptive pills (ECPs) are licensed in Canada to prevent pregnancy after unprotected intercourse or suspected contraceptive failure. Both inhibit or delay ovulation. Levonorgestrel (PLAN B® and generics) has been used since the early 1970’s for “morning after” contraception, and was approved in Canada in 1999 for use within 72 hours (3 days) of sexual intercourse. Ulipristal acetate (ella®) was approved in Canada in 2015 for use within 120 hours (5 days). It is uncertain whether one drug is more efficacious beyond 72 hours after sexual intercourse, or for people whose body weight exceeds 80 kg or BMI (body mass index) exceeds 30 kg/m2 . In British Columbia, generic levonorgestrel is easy to obtain and free of charge. Ulipristal requires a prescription and costs about $40. Methods: We conducted a systematic review to compare the efficacy and safety of levonorgestrel with ulipristal. Results: Two randomized controlled trials (RCTs) compared levonorgestrel with ulipristal for emergency contraception. For use within 72 hours (3 days) of unprotected intercourse, we found no significant difference in pregnancy rates and short-term safety between levonorgestrel and ulipristal. From 72 to 120 hours (3 to 5 days) of unprotected intercourse, comparative efficacy is not well established - primarily related to small sample sizes. Limited and inconclusive data from one non-randomized study suggest consistent efficacy of ulipristal up to 120 hours, whereas an analysis of 4 RCTs of levonorgestrel suggested that its efficacy decreased only beyond 96 hours after intercourse. Based on similarly low quality data, there has been concern that efficacy of both levonorgestrel and ulipristal may decrease at body weights >80 kg or BMI >30 kg/m2 . This is challenged by the findings of 2 reviews, and by a recent RCT. Conclusions: Within 72 hours (3 days) of unprotected intercourse, the relative efficacy of levonorgestrel and ulipristal to prevent unwanted pregnancy is not established conclusively. From 72 to 120 hours (3 to 5 days), relative efficacy is also not well established. It remains uncertain whether body weight >80 kg or BMI >30 kg/m2 reduce efficacy of ECPs at standard doses, at any time point.

Other

eng

2024-09-25

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89292

Reviewed

http://creativecommons.org/licenses/by-nc-nd/4.0/