The importance of pharmacokinetic studies in drug development

摘要

The current issue of Contraception has five articles related to the absorption, serum and tissue levels, metabolism and bioequivalence of contraceptive hormones. Stanczyk et al. present a review article on the pharmacokinetics and pharmacodynamics of ethinyl estradiol and estradiol. The introduction of estradiol in a new combination oral contraceptive (COC) required an evaluation of the similarities and differences between them. There are differences in pharmacokinetics of a transdermal patch containing ethinyl estradiol (EE) and levonorgestrel when applied at three different sites -buttock, lower abdomen and upper torso. Despite these differences, the delivery of the hormones maintains clinical efficacy (Stanczyk et al.). The duration of effect after discontinuation of contraceptive hormones or the terminal half life of the product is important especially in terms of missed pills in a contraceptive regimen.