The bioequivalence of the contraceptive steroids ethinylestradiol and drospirenone is not affected by co-administration of dehydroepiandrosterone

Objectives To study the effect of co-administration of 50 mg dehydroepiandrosterone (DHEA) on the bioequivalence of ethinylestradiol (EE) and drospirenone (DRSP) in women who were using a combined oral contraceptive (COC) containing 30 mu g EE and 3 mg DRSP, and to estimate whether the addition of DHEA to this COC affects the serum levels and the bioequivalence of the synthetic contraceptive steroids. Methods This was a randomised, double-blind, two-period crossover study. Participants received two EE/DRSP COC treatment cycles in random order, one with and one without daily 50 mg DHEA, separated by a 28-day wash-out cycle during which the subjects used an EE/levonorgestrel (LNG) COC without DHEA. Serum levels of EE and DRSP were measured according to a sampling scheme allowing pharmacokinetic evaluations. Results Addition of DHEA to an EE/DRSP COC had no effect on serum levels of EE and DRSP. The COC regimens with and without DHEA were bioequivalent. Oestradiol levels were equally suppressed during pill intake, whether with placebo or DHEA. Conclusion Adding DHEA to a COC containing EE and DRSP does not affect the pharmacokinetic properties of EE and DRSP. Therefore, it will most likely not affect its contraceptive efficacy.