title: The relative bioavailability of levonorgestrel and ethinyl estradiol administered as a low-dose combination oral contraceptive.
abstract: The relative bioavailability of levonorgestrel (LNG) and ethinyl estradiol (EE) administered concomitantly both as an oral tablet and as a solution was assessed in a randomized two-period crossover study in 24 healthy women. Serum concentrations were monitored for 96 h after each administration. The relative bioavailability (Fr) of LNG in the tablet with respect to the solution was 107%; thus the two formulations were bioequivalent with respect to LNG. The relative bioavailability of EE, however, was significantly lower for the tablet (Fr 83%) compared to the solution. This difference may have been due to either decreased absorption or enhanced presystemic elimination of EE from the tablet formulation.
mesh_terms: D000328:Adult; D001682:Biological Availability; D003277:Contraceptives, Oral, Combined / Q000097:blood*; D004997:Ethinyl Estradiol / Q000008:administration & dosage / Q000097:blood*; D005260:Female; D006801:Humans; D007700:Kinetics; D016912:Levonorgestrel; D009644:Norgestrel / Q000008:administration & dosage / Q000097:blood*
chemical_list: D003277:Contraceptives, Oral, Combined; D009644:Norgestrel; D004997:Ethinyl Estradiol; D016912:Levonorgestrel