For Obese Women, Continuous, Increased Dosing of OCs May Be Best
the MPR take:
For women who are obese, the efficacy of birth control pills may not be the same as for those who are not. A new study published in the journal Contraception aims to determine ways to improve the pharmacokinetic alterations that may occur in obese patients taking oral contraceptives. In the study, a total of 31 obese women received an oral contraceptive containing levonorgestrel 100mcg/ethinyl estradiol 20mcg; the pills were taken for 21 days with a 7-day placebo week. After two cycles on this oral contraceptive, the women were then randomized to receive either the same oral contraceptive to be given on a continuous cycle (no placebo week) or an oral contraceptive that contained an increased dose (levonorgestrel 150mcg/ethinyl estradiol 30mcg; 21 days active pills, 7 days placebo). Both of these methods (continuous dosing and increased dosing) helped to counteract the effects obesity has on the pharmacokinetics of oral contraceptives. Whether improving the pharmacokinetics of the drug improves efficacy is still under debate, the pharmacokinetics of very low dose oral contraceptives have been shown to be adversely affected by obesity.
Objective: To determine if increasing the hormone dose or eliminating the hormone-free interval improves key pharmacokinetic (PK) alterations caused by obesity during oral contraceptive (OC) use. Study design: Obese [body mass index (BMI)≥30 kg/m2], ovulatory, otherwise healthy, women received an OC containing 20mcg ethinyl estradiol (EE)/100mcg levonorgestrel (LNG) dosed cyclically (21 days active pills with 7-day placebo week)...