THE EFFECT OF DOXYCYCLINE ON THE EFFICACY OF ORAL CONTRACEPTIVE PILLS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 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身体对避孕类固醇的暴露，导致合理的担忧，即避孕效果可能会降低或丧失。 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联合使用的频率，这种功效降低的可能性变得更大。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炭疽感染爆发期间，这种抗生素预计会广泛使用。 我们计划量化长期多西环素给药对炔雌醇和炔雌醇的药代动力学以及对作为排卵替代标志物的促黄体生成素（LH）、促卵泡激素（FSH）和孕酮的血浆浓度的影响。突破性出血的频率将作为口服避孕药有效性的附加指标。 这将是一项开放标签、固定顺序、两阶段（每个阶段两个周期）、24名志愿者参与的研究。

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 nonrethindrone 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.