Effectiveness of Orally Dosed Emergency Contraception in Obese Women - UPA

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.

Our preliminary data provides evidence for testing a dose escalation strategy in an effort to provide improved efficacy from orally-dosed EC in obese women. We hypothesize 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, we plan to perform detailed pharmacokinetic and pharmacodynamic studies of UPA-based EC in obese women and expand upon our preliminary findings of LNG-based EC. This protocol registration is for the UPA aspect of the study procedures focused on the pharmacokinetics and pharmacodynamics of UPA and will include a dose escalation intervention.

Inclusion criteria

• Generally healthy women
• Aged 18-35 years old
• Regular menses (every 21-35 days) experiencing an ovulatory screening cycle with a progesterone level of 3 ng/mL or greater
• Subjects must have a BMI of >30kg/m2 and weight at least 80kg or more OR a BMI <25kg/m2 and a weight of less than 80kg.

Exclusion criteria

• Metabolic disorders including uncontrolled thyroid dysfunction and Polycystic Ovarian Syndrome
• Impaired liver or renal function
• Actively seeking or involved in a weight loss program (must be weight stable) pregnancy, breastfeeding, or seeking pregnancy
• Recent (within last 8 weeks) use of hormonal contraception
• Current use of drugs that interfere with metabolism of sex steroids
• Smokers.