Impact of the SLCOIBI polymorphism on the pharmacokinetics and lipid-lowering efficacy of multiple-dose pravastatin

Background and Objective: The polymorphism of SLCO1B1 (solute carrier organic anion transporter family, member 1B1), encoding the hepatic uptake transporter organic anion transporting polypeptide 1B1, has been associated with increased pravastatin concentrations in single-dose studies. We have investigated whether this polymorphism influences the pharmacokinetics and lipid-lowering efficacy of multiple-dose pravastatin. Methods: A prospective, parallel-group study of 16 healthy volunteers, including 8 carriers of an SLCO1B1 variant haplotype and 8 control subjects, was carried out. Pravastatin pharmacokinetics and reduction in total and low-cicilsity lipoprotein (LDL) cholesterol concentrations were analyzed after treatment with 40 mg pravastatin daily for 3 weeks. Results: The mean area under the plasma concentration-time curve of pravastatin was 110% higher (305.0 +/- 149.4 ng (.) h/mL [mean +/- SD] versus 144.9 +/- 48.2 ng (.) h/mL, P =.012) and the mean peak concentration in plasma was 231% higher (174.5 +/- 98.6 ng/mL versus 52.7 +/- 22.1 ng/mL, P =.0042) in the SLCO1B1 variant haplotype group than in the control group. Pravastatin significantly reduced the concentrations of total and LDL cholesterol in both groups. The mean percentage reduction in total cholesterol concentration was 13.1% +/- 9.1% and 19.1% +/- 8.3% in the variant and control groups, respectively (P =.19; 95% confidence inter-vat of difference between groups, -15.3% to 3.3%). The mean percentage reduction in LDL cholesterol concentration was 27.7% +/- 8.3% in the variant group and 32.3% +/- 11.2% in the control group (P =.37; 95% confidence interval for difference, -15.1% to 6.0%). Conclusions: Despite considerably higher plasma pravastatin concentrations in carriers of all SLCO1B1 variant haplotype, there was no significant difference in the lipid-lowering efficacy of pravastatin between the variant haplotype and control groups. However, this pilot study had sufficient statistical power to detect only a large difference in lipid response between the 2 groups. Further clinical studies are warranted to characterize the impact of the SLCO1B1 polymorphism on the lipid response to pravastatin.