CYP2C9 genotypes and the quality of anticoagulation control with warfarin therapy among Brazilian patients.

Objective: To evaluate the impact of the two most common CYP2C9 variant alleles (*2 and *3) on the maintenance dose of warfarin and on the quality of anticoagulation control in Brazilians.

Methods: Patients (n = 103) initiated warfarin therapy with 5 mg/day (or 2.5 mg/day when over 80 years old).