Enzymatic activity on valsartan of 38 CYP2C9 variants from the Chinese population

Valsartan is widely used for the treatment of moderate hypertension. However, previous studies have found that efficacy of the valsartan depends on the dose and intake. Cytochrome P450 (CYP) 2C9 metabolizes ∼15% of the clinical drugs. Genetic polymorphisms of CYP2C9 markedly affect the safety and effectiveness of many drugs, which might lead to adverse reactions and therapeutic failure. Twenty-four novel CYP2C9 variants (*36-*60) had been previously discovered via gene sequencing in the Han population. Our study aims to evaluate the impact of 38 CYP2C9 variants from the Chinese population on valsartan metabolism compared with CYP2C9*1 in vitro.

Wild-type CYP2C9*1 and other CYP2C9 variants were expressed in Spodoptera frugiperda 21 insect cells. Incubations were performed at 37 °C with 20-2000 μM substrate for 30 min. The metabolite 4-OH valsartan was determined via UPLC-MS/MS.

Among the 38 CYP2C9 variants, the enzymatic activities of most variants were significantly altered compared with the wild-type. Three variants (CYP2C9*27, *40 and *49) exhibited increased intrinsic clearance values (134-153% relative clearance). However, 12 variants (CYP *8, *13, *16, *19, *33, *36, *42, *43, *45, *52, *54, *58) caused >90% decreases in the relative clearance of valsartan compared to CYP2C9*1.

Our research provides systematic data for evaluating the effects of CYP2C9 variants on valsartan metabolism in the Chinese population. These results will expand our understanding of the impact of CYP2C9 genetic polymorphisms on valsartan metabolism and will contribute to precision medicine.