Department of Obstetrics & Gynecology, Oregon Health & Science University, Portland, Oregon; Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, Beaverton, Oregon.
Department of Obstetrics & Gynecology, Oregon Health & Science University, Portland, Oregon; Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, Beaverton, Oregon.
Contraception. 2018 Dec;98(6):463-466. doi: 10.1016/j.contraception.2018.08.003. Epub 2018 Aug 14.
To determine if a combined oral contraceptive (COC) initiated shortly after ulipristal acetate (UPA) administration interferes with its mechanism of action.
Healthy, reproductive-age women of normal BMI with proven ovulation (serum progesterone >3 ng/ml) were enrolled for three cycles (Cycle 1, UPA only; Cycle 2 washout; Cycle 3 UPA plus COC). During Cycles 1 and 3, subjects were monitored with transvaginal ultrasound and blood sampling for progesterone and LH every other day until a dominant follicle measuring >15 mm was visualized. In both treatment cycles, subjects received UPA (30mg) and were followed daily with similar monitoring for up to 7 days. In Cycle 3 only, subjects initiated a daily COC (0.15 mg levonorgestrel/30 μg ethinyl estradiol) 2 days after UPA. The study had 80% power to detect a 15% difference in the proportion of cycles with at least a 5-day delay in follicle rupture. We assessed follicle rupture as >50% decrease in mean size and adjudicated unclear outcomes with serum hormones.
A total of 36 women enrolled and 33 completed all study procedures [age 28.4 years (SD 3.9); BMI 23.4 (SD 2.4)]. Compared to Cycle 1, more subjects demonstrated evidence of follicle rupture in <5 days in Cycle 3 [1/33 (3%) vs. 9/33 (27%), p = .008]. We also included data from 2 subjects who experienced rupture prior to COC dosing in the analysis.
UPA's effectiveness is significantly reduced by administering COCs 2 days later.
This study demonstrates that UPA's efficacy as an emergency contraceptive is reduced with early exposure to COCs.
确定在屈螺酮（COC）给药后不久开始使用复方口服避孕药（COC）是否会干扰其作用机制。
健康、具有正常 BMI 的育龄妇女，经证实排卵（血清孕激素>3ng/ml），入组三个周期（第 1 周期，仅屈螺酮；第 2 周期洗脱；第 3 周期屈螺酮加 COC）。在第 1 周期和第 3 周期，通过阴道超声和每两天一次的孕激素和 LH 采血监测，直到观察到>15mm 的优势卵泡。在两个治疗周期中，所有受试者均接受屈螺酮（30mg）治疗，并在最多 7 天内每天进行类似监测。仅在第 3 周期，受试者在屈螺酮给药后 2 天开始每日服用 COC（0.15mg 左炔诺孕酮/30μg 乙炔雌二醇）。该研究有 80%的效力检测出卵泡破裂延迟>5 天的周期比例差异为 15%。我们评估卵泡破裂的标准为平均大小减少>50%，并根据血清激素结果判定不明确的结果。
共有 36 名女性入组，33 名女性完成了所有研究程序[年龄 28.4 岁（标准差 3.9）；BMI 23.4（标准差 2.4）]。与第 1 周期相比，第 3 周期中<5 天有更多受试者显示卵泡破裂的证据[1/33（3%）比 9/33（27%），p=0.008]。我们还将 2 名在开始服用 COC 前就发生破裂的受试者的数据纳入分析。
COC 给药后 2 天内使用屈螺酮会显著降低其有效性。
这项研究表明，屈螺酮作为紧急避孕药的疗效会因早期接触 COC 而降低。
