Warfarin Dose Maintenance Associated with CYP2C9*2 (rs1799853) and CYP2C9*3 (rs1057910) Gene Polymorphism in North Coastal Andhra Pradesh

Deep Vein Thrombosis (DVT) is a high-risk condition that necessitates the use of oral anticoagulants for treatment. Warfarin, a common anticoagulant, exhibits varying levels of efficacy and toxicity among individuals. The CYP2C9 gene promoter polymorphism significantly influences the dosage requirements, a factor that remains underexplored in the contemporary Indian population.

This study aimed to investigate the influence of CYP2C9 gene polymorphisms on warfarin dosage due to pharmacogenetic effects. Specifically, it examined the prevalence of the CYP2C9 polymorphic alleles *2 and *3 and their correlation with warfarin dosage in the South Indian Population (NCAP).

The study involved 96 warfarin-treated patients to determine the genotype frequency of common CYP2C9 polymorphisms. The genotypes of CYP2C92 and CYP2C93 polymorphisms were analyzed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. A one-way analysis of variance (ANOVA) was conducted to ascertain dosage variation across genotypes.

The study found that the frequencies of the two variations were 25.5% for CYP2C92 and 40.6% for CYP2C93. Patients with a homozygous wild-type genotype for CYP2C9 (*1/*1) required a daily warfarin dose of 4.07 ± 1.75 mg, significantly higher than the *1/*2, *1/*3 (2.93 ± 2.03 mg, p <0.0001) and *2/*2, *2/*3, and *3/*3 patients (1.54± 1.05 mg, p = 0.002). The study also revealed a distinct allelic frequency of CYP2C9 polymorphisms in the study population compared to other populations.

Given the relatively high prevalence of CYP2C9 polymorphisms in the studied population, practitioners should consider these findings to minimize the risk of bleeding when prescribing warfarin.