Comparison of Empiric and Pharmacogenetic Approaches in Assessment of Efficacy of Anticoagulant Therapy
We compared pharmacogenetic (PG) and standard approaches to selection of individual dose of warfarin on 2 groups of patients each comprising 17 persons. In the group with PG selection we took into consideration the result of preliminary genotyping of polymorphisms of VKORC1 and CYP2C9 genes known to be associated with individual warfarin dose. Control of warfarin therapy was carried out during 6 months, number of measurements of international normalized ratio (INR) exceeded 500. Dosing based on knowledge of genotype allowed to achieve therapeutic effect 5 days earlier than with traditional selection of individual dose (р = 0.023). Number of INR values above 3.5 indicative of increased risk of bleeding was lower at PG compared with standard approach (3.1 and 7.7%, respectively, р = 0.03). Carriers of *2 and/or *3 of CYP2C9 associated with lowering of activity of this cytochrome had greater lability of INR values during course of therapy with warfarin.