The Impact of CYP 2C9 rs1799853 and rs1057910 Polymorphism on Plasma Losartan Metabolic Ratio in a Sample of Iraqi Hypertensive Patients

Background: The challenge associated with interindividual diversity in CYP2C9 enzyme activity is primarily related to genetic variations among individuals. Polymorphisms in the CYP2C9 gene can lead to different enzyme activity, affecting how individuals metabolize drugs. The understanding of interindividual diversity in CYP2C9 enzyme activity has implications for personalized medicine. Objective: To examine the impact of CYP2C9 gene polymorphisms (rs1799853 and rs1057910) on the losartan metabolism in Iraqi hypertensive patients. Methods: This prospective interventional study was conducted on a sample of hypertension patients from Babylon governorate, Iraq. All patients received 100 mg of losartan once daily. After 4 weeks, blood samples were obtained for genetic analysis and measuring losartan and its carboxylic acid (LCA) metabolite levels. The plasma losartan-to-LCA ratio is used as an indirect determinant of CYP2C9 activity within CYP2C9 SNP genotypes. Results: Two major allelic polymorphisms, CYP2C9 rs1799853 (T allele 15.5%) on exon 3 and rs1057910 (C allele 8.5%) on exon 7, have been identified among the patients. Plasma losartan/E3174 metabolic ratio was significantly higher in patients with a CT genotype of rs1799853 SNP (1.65) than in patients with a CC wild-type genotype (1.03). The losartan/E3174 metabolic ratio in heterozygous mutant AC genotypes of rs1057910 (1.18) was also higher than in those with wild-type AA genotypes (1.15); however, these differences are not statistically significant. Conclusions: The rs1799853 SNP variant, but not the rs1057910 SNP variant, significantly impacts CYP2C9 metabolic activity. The plasma losartan/E3174 metabolic ratio appears to be a practical and reliable measure for CYP2C9 activity.