Pharmacokinetics of ethynyl estradiol: a current view.

There are large discrepancies in the values reported for the parameters of ethynyl estradiol pharmacokinetics. Economies in sampling frequency (in the hope that computer simulation will serve the purpose), difficulties in measurement of plasma levels resulting from the small doses used, extensive oxidative metabolism, distribution, and enterohepatic circulation all complicate the effort to obtain reliable data. The problems in quantitating various pharmacokinetic parameters and the techniques for their evaluation, as well as methods for the determination of the requisite sampling times and frequencies are discussed, and best estimates for the various parameters, as derived from the literature, are provided.