Effects of SLCO1B1 and SLCO1B3 Genetic Polymorphisms on Valsartan Pharmacokinetics in Healthy Korean Volunteers

Abstract

Purpose: This study aimed to examine OATP1B1 (SLCO1B1) and OATP1B3 (SLCO1B3) on the pharmacokinetics of valsartan. Twenty-five subjects were genotyped for 16 single-nucleotide polymorphisms of the SLCO1B1 and SLCO1B3 genes. Methods: After a single dose of 160 mg of valsartan was orally administered to healthy male volunteers, drug concentrations were assayed up to 48 h. The 25 subjects were genotyped for 16 single-nucleotide polymorphisms (SNPs) of the SLCO1B1 and SLCO1B3 genes. Subjects were classified into groups according to their SLCO1B1*1B haplotype; 23 subjects were carriers of SLCO1B1*1B and two subjects were included in the reference group with SLCO1B1*1A/*1A. Alternations of the splicing factor-binding site pattern caused by the given mutation were evaluated with the Human Splicing Finder (HSF) 3.1. Results: The subjects who carried SLCO1B1*1B showed a 2.3-fold higher clearance than those without the *1B haplotype. Mean C-max and AUC(inf) were reduced by 45% and 54%, respectively, in the SLCO1B1*1B genotype group compared to the reference group with the *1A/*1A genotype (p < 0.01). The carriers of the rs4149153 T allele of SLCO1B3 had a 27% lower mean C-max and a 1.5-fold higher Vd compared to homozygotic CC carriers (p < 0.05). In a combined analysis of SLCO1B1 and SLCO1B3, subjects not carrying SLCO1B1 *1B and carrying SLCO1B3 rs4149153 T allele showed a 1.6-fold higher clearance than those with the other genotypes, whereas mean C-max and AUC(last) were reduced by 35% and 42%, respectively (p < 0.05), in the subjects. HSF 3.1 analysis showed that rs4149153 could cause alterations of the acceptor splice site (TAAATACTAAAGAC to TAAATATTAAAGAC) with scoring change (from 72.57 to 71.92, difference = -0.9). Conclusion: It was found that plasma exposure to valsartan is significantly decreased in SLCO1B1*1B carriers and carriers of the rs4149153 T allele of SLCO1B3, possibly as a result of increased hepatic uptake.