The rationale for use of Ulipristal Acetate as first line in emergency contraception: biological and clinical evidence

Abstract

Ulipristal acetate (UPA) was licensed as an emergency contraceptive (EC) in Europe in 2009. By the end of May 2013, over 1.4 million courses had been used. The rationale for using UPA for EC in favor of the much more commonly used levonorgestrel (LNG) is based on data on efficacy, safety and side effects.

Efficacy: In two large clinical trials among women presenting for EC up to 120 hours after unprotected sex, UPA was as effective as LNG at preventing pregnancy. When the two trials were combined in a meta analysis UPA was superior, almost halving the risk of pregnancy compared with LNG. Biomedical studies have shown that UPA inhibits or delays ovulation more effectively than LNG at a stage of the cycle when the risk of pregnancy is highest.

Safety and side effects: UPA and LNG have similar side effect profiles and to date no serious adverse events have been attributed to use of UPA for EC. Data on pregnancies conceived in association with UPA use are reassuring. There is no evidence for teratogenesis or for any increased risk of ectopic pregnancy or miscarriage.

Availability: Use of UPA will remain limited until it is available without a doctor’s prescription.

Chinese abstract

2009年，醋酸乌利司他（UPA）在欧洲获得许可，开始被作为紧急避孕药（EC）。至2013年5月，已有超过140万例女性使用该药物。同为EC，UPA与左炔诺孕酮（LNG）相比获得了更多的支持，其理论依据为有效性、安全性及副作用的相关数据。有效性：在两项大型临床试验中，嘱女性在无预防措施性交后120个小时服用紧急避孕药，发现UPA与LNG的避孕效果相当。使用meta分析将两项试验结合，结果显示UPA更优，妊娠风险与LNG相似。生物医学研究证实，在生理周期中妊娠风险最高的时期，UPA的阻滞或延迟排卵作用比LNG更加有效。安全性及副作用：UPA与LNG有着相似的副作用，但至今并未发现因使用UPA作为EC而引发的严重不良事件。服用UPA后避孕失败而受孕的例数较少，相关数据令人满意。至今没有证据表明UPA会致畸或增高异位妊娠及流产的风险。使用限制：在成为非处方药物之前，UPA的使用仍受较大限制。

• Availability cost
• efficacy
• emergency contraception
• safety
• Ulipristal acetate