PIII‐49

BACKGROUND The risk of thromboembolic events in women using hormonal contraceptive products is a concern. Doses of ethinyl estradiol (EE) have been progressively decreased following the recognition of estrogen‐related adverse effects. The purpose of this study was to compare the EE exposure among approved contraceptive products in the U.S. METHODS The contraceptives containing EE were identified. Labels were obtained from the Physicians' Desk Reference. A literature search of pharmacokinetic (PK) data was conducted if labels did not contain the PK. The following information was collected from the labels and published PK studies: drug, route of administration, dosage strength of EE, dosing regimen, and PK parameters of EE (C max , C ss , C avg , AUC). RESULTS Our search identified 95 contraceptive products containing various EE doses. We report the preliminary findings of 15 EE products. Of these, 13 drug products were oral contraceptives (OCs), 1 was a transdermal patch (TP) and one was a vaginal ring (VR). EE daily doses ranged from 15 to 40 mcg. In general, C max of EE was higher from the OCs compared to the TP/VR products. AUC of EE from the TP was generally higher compared to the OCs/VR products when dose‐normalized. Inter‐subject variability for EE PK parameters from the TP was higher relative to the variability determined from the OCs. CONCLUSIONS Further investigation is ongoing to understand how different routes of administration of contraceptive products containing EE have an effect on EE exposure. Clinical Pharmacology & Therapeutics (2005) 79 , P71–P71; doi: 10.1016/j.clpt.2005.12.257