Department of Women's and Children's Health, Division of Obstetrics and Gynecology, Karolinska Institutet, Stockholm, Sweden.
Int J Womens Health. 2010 Aug 9;2:53-61. doi: 10.2147/ijwh.s5865.
Unintended pregnancy is a global reproductive health problem. Emergency contraception (EC) provides women with a safe means of preventing unwanted pregnancies after having unprotected intercourse. While 1.5 mg of levonorgestrel (LNG) as a single dose or in 2 doses with 12 hours apart is the currently gold standard EC regimen, a single dose of 30 mg ulipristal acetate (UPA) has recently been proposed for EC use up to 120 hours of unprotected intercourse with similar side effect profiles as LNG. The main mechanism of action of both LNG and UPA for EC is delaying or inhibiting ovulation. However, the 'window of effect' for LNG EC seems to be rather narrow, beginning after selection of the dominant follicular and ending when luteinizing hormone peak begins to rise, whereas UPA appears to have a direct inhibitory effect on follicular rupture which allows it to be also effective even when administered shortly before ovulation, a time period when use of LNG is no longer effective. These experimental findings are in line with results from a series of clinical trials conducted recently which demonstrate that UPA seems to have higher EC efficacy compared to LNG. This review summarizes some of the data available on UPA used after unprotected intercourse with the purpose to provide evidence that UPA, a new type of second-generation progesterone receptor modulator, represents a new evolutionary step in EC treatment.
意外怀孕是一个全球性的生殖健康问题。紧急避孕（EC）为女性提供了一种安全的方法，以防止在无保护的性行为后意外怀孕。虽然 1.5 毫克左炔诺孕酮（LNG）作为单剂量或 12 小时间隔的 2 剂量是目前的 EC 黄金标准方案，但最近提出将 30 毫克乌利司他醋酸盐（UPA）作为单剂量用于 EC，可在无保护的性行为后 120 小时内使用，其副作用与 LNG 相似。LNG 和 UPA 用于 EC 的主要作用机制是延迟或抑制排卵。然而，LNG EC 的“作用窗口”似乎相当狭窄，从选择优势卵泡开始，到黄体生成素峰值开始上升结束，而 UPA 似乎对卵泡破裂有直接抑制作用，因此即使在排卵前不久给药也有效，而此时使用 LNG 已不再有效。这些实验结果与最近进行的一系列临床试验的结果一致，这些试验表明 UPA 似乎比 LNG 具有更高的 EC 效果。这篇综述总结了一些关于无保护性行为后使用 UPA 的现有数据，旨在提供证据表明，作为一种新型第二代孕激素受体调节剂，UPA 在 EC 治疗中代表了一个新的进化步骤。
