Effectiveness of Orally Dosed Emergency Contraception in Obese Women - LNG

Obese women are significantly more likely than their normal BMI counterparts to experience failure of orally-dosed emergency contraceptives. The PI's preliminary data provides evidence for testing a dose escalation strategy in an effort to provide improved efficacy from orally-dosed emergency contraceptives in obese women. The overall project will be focused on both levonorgestrel (LNG) - and ulipristal acetate-containing emergency contraception but this protocol registration is for the LNG aspect of the study procedures.

Emergency contraception (EC) provides a woman with an additional line of defense against unintended pregnancy following an act of unprotected intercourse. Orally-dosed EC works by delaying ovulation and reduces the risk of pregnancy for a single act of unprotected intercourse by 50-70%. Unfortunately, obese women are significantly more likely than their normal BMI counterparts to experience failure of orally-dosed EC and in some instances EC is equivalent to placebo. The PI's preliminary data provides evidence for testing a dose escalation strategy in an effort to provide improved efficacy from orally-dosed EC in obese women. The hypothesis is that increasing the dose of orally-dosed EC agents will normalize the pharmacokinetics resulting in the expected treatment effect (delay in follicle rupture) in obese women. In the overall proposal, the investigators plan to perform detailed pharmacokinetic and pharmacodynamic studies of ulipristal acetate-based EC in obese women and expand upon the preliminary findings of levonorgestrel-based EC. This protocol registration is for the LNG aspect of the study procedures focused on the pharmacodynamics of LNG dose escalation