Determinants of Warfarin Metabolism

The anticoagulant effect of warfarin varies greatly among individuals. Some of this variability is attributed to differences in the activity of CYP2C9, the predominant enzyme involved in the metabolism of S-warfarin. The present study is designed to define the differences in warfarin metabolism among healthy individuals carrying different CYP2C9 genotypes. In addition, the study will define the correlation between the phenytoin metabolic ratio, a marker of CYP2C9 activity in vivo, and warfarin metabolism.

Inclusion Criteria: * Age range of 20-50 years old * The absence of significant disease states Exclusion Criteria: * Known hypersensitivity to warfarin or phenytoin * Known hepersensitivity to penicillins or cephalosporins (Dicloxacillin part) * The presence of significant disease states * Regular use of drugs (including birth control pills)