Obstetrics & Gynecology, Baylor College of Medicine, Houston, TX, USA.
Adv Ther. 2011 Feb;28(2):87-90. doi: 10.1007/s12325-010-0090-x. Epub 2010 Dec 10.
Emergency contraception is a woman's last chance to prevent unintended pregnancy. Ulipristal acetate, a selective progesterone receptor modulator, when taken as a single 30 mg dose, is a new, safe and effective emergency contraceptive that can be used from the first day and up to 5 days following unprotected intercourse. The older progesterone-only emergency contraceptive, levonorgestrel, is taken as two 0.75 mg pills 12 hours apart (Next Choice(®); Watson Pharmaceuticals Inc., Morristown, NJ, USA) or a single 1.5 mg pill (Plan B One-Step™; Watson Pharmaceuticals Inc.), and is approved for only 72 hours after unprotected intercourse. During clinical development, ulipristal acetate has been shown to be more effective than levonorgestrel in delaying or inhibiting ovulation. A recent meta-analysis of two randomized clinical trials showed ulipristal acetate to have a pregnancy risk 42% lower than levonorgestrel up to 72 hours and 65% lower in the first 24 hours following unprotected intercourse. Moreover, when taken beyond 72 hours, significantly more pregnancies were prevented with ulipristal acetate than with levonorgestrel. Side effects are mild and similar to those seen with levonorgestrel. Ulipristal acetate was approved for emergency contraception by the US Food and Drug Administration in August 2010, and has been launched in the USA as ella(®) (Watson Pharmaceuticals Inc.) since December 1, 2010. Ella is prescription only and is priced comparable to Plan B One-Step.
紧急避孕是女性防止意外怀孕的最后机会。屈螺酮是一种选择性孕激素受体调节剂，单次服用 30 毫克即可作为一种新的、安全有效的紧急避孕药，可在无保护性交后的第一天至第五天使用。较老的孕激素紧急避孕药左炔诺孕酮需要间隔 12 小时服用两片 0.75 毫克的药片（Next Choice（®）；Watson Pharmaceuticals Inc.，Morristown，NJ，USA）或服用一片 1.5 毫克的药片（Plan B One-Step™；Watson Pharmaceuticals Inc.），并且仅在无保护性交后 72 小时内批准使用。在临床开发过程中，屈螺酮已被证明比左炔诺孕酮更有效地延迟或抑制排卵。最近的两项随机临床试验的荟萃分析表明，屈螺酮在无保护性交后 72 小时内的妊娠风险比左炔诺孕酮低 42%，在头 24 小时内低 65%。此外，在超过 72 小时后，服用屈螺酮的妊娠预防率明显高于左炔诺孕酮。副作用轻微，与左炔诺孕酮相似。屈螺酮于 2010 年 8 月获得美国食品和药物管理局批准用于紧急避孕，并于 2010 年 12 月 1 日在美国以 ella（®）（Watson Pharmaceuticals Inc.）的形式推出。ella 为处方用药，价格与 Plan B One-Step 相当。
