THE EFFECT OF DOXYCYCLINE ON THE EFFICACY OF ORAL CONTRACEPTIVE PILLS

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。口服避孕药和口服抗生素之间的药物相互作用可能会减少人体对避孕类固醇的暴露，从而导致避孕效果可能降低或丧失的合理担忧。近年来，由于口服避孕药的推荐剂量较低以及抗生素和口服避孕药合用的频率较低，这种降低疗效的可能性更大。与强力霉素的相互作用特别令人感兴趣，因为在生物恐怖袭击后爆发炭疽感染期间，这种抗生素预计会被广泛使用。我们计划量化长期服用强力霉素对炔雌醇和去甲稀酮药代动力学的影响，以及对血浆促黄体生成素（LH）、促卵泡激素（FSH）和黄体酮（排卵的替代指标）浓度的影响。突破性出血的频率将被确定为口服避孕药疗效的附加指标。这将是一个开放标签，固定顺序，两个周期（每个周期两个周期），24名志愿者的研究。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The drug interaction between oral contraceptives and oral antibiotics may reduce the exposure of the body to the contraceptive steroids leading to the legitimate concern that contraceptive efficacy may be reduced or lost. This potential for reduced efficacy has become more likely in recent years because of the lower recommended doses of oral contraceptives and the frequency with which antibiotics and oral contraceptives are co-prescribed. An interaction with doxycycline is of particular interest because of the expected widespread use of this antibiotic during an outbreak of anthrax infection following a bioterrorism attack. We plan to quantify the effect long-term doxycycline dosing on the pharmacokinetics ethinylestradiol and norethindrone and on the plasma concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH) and progesterone as surrogate markers of ovulation. The frequency of breakthrough bleeding will be determined as an additional index of oral contraceptive efficacy. This will be an open-label, fixed order, two-period (two cycle per period), study of 24 volunteers.