Relative Bioavailability of Ethinyl Estradiol from Two Different Oral Contraceptive Formulations after Single Oral Administration to 18 Women in an Intraindividual Cross-Over Design

Two low-dose oral contraceptives, both containing the same dose of ethinyl estradiol (EE₂) but different progestins (gestodene and desogestrel, respectively), were compared with respect to the relative bioavailability of EE₂. After single-dose administration of both formulations to 18 women in an intraindividual cross-over design, there was no difference in the target variables for EE₂ (Cmax, tmax and AUC). With respect to EE₂, both formulations were bioequivalent. The observation of others, reporting higher EE₂ levels in the serum of women taking the gestodene-containing formulation as compared to those taking the desogestrel-containing formulation, was not confirmed.