UDP-glucuronosyltransferase (UGT) polymorphisms affect atorvastatin lactonization in vitro and in vivo.

The response to statins shows large interpatient variability. Atorvastatin delta-lactone is pharmacologically inactive but has been associated with toxicity. We investigated the role of UDP-glucuronosyltransferases (UGTs) in atorvastatin lactonization. In human liver microsomes, lactonization was correlated with UGT1A3 (r(s) = 0.61, P < 0.0001) but not with UGT1A1. Surprisingly, lactone formation was significantly higher in carriers of UGT1A1*28, an allele that is associated with lower UGT1A1 expression. We show that this inverse correlation is due to extensive linkage disequilibrium in the UGT1A locus and that several UGT1A3 haplotypes are associated with strong increases in UGT1A3 expression in vitro. Analyses of the pharmacokinetic parameters of atorvastatin and metabolites in genotyped volunteers confirmed that there is an increase in atorvastatin lactonization in carriers of UGT1A3*2 in vivo. The potential of UGT genotyping to identify patients who are at increased risk for failure of therapy and/or adverse effects of statins warrants further investigation.

ABCG2 polymorphism markedly affects the pharmacokinetics of atorvastatin and rosuvastatin.

The ABCG2 c.421C>A single-nucleotide polymorphism (SNP) was determined in 660 healthy Finnish volunteers, of whom 32 participated in a pharmacokinetic crossover study involving the administration of 20 mg atorvastatin and rosuvastatin. The frequency of the c.421A variant allele was 9.5% (95% confidence interval 8.1-11.3%). Subjects with the c.421AA genotype (n = 4) had a 72% larger mean area under the plasma atorvastatin concentration-time curve from time 0 to infinity (AUC(0-infinity)) than individuals with the c.421CC genotype had (n = 16; P = 0.049). In participants with the c.421AA genotype, the rosuvastatin AUC(0-infinity) was 100% greater than in those with c.421CA (n = 12) and 144% greater than in those with the c.421CC genotype. Also, those with the c.421AA genotype showed peak plasma rosuvastatin concentrations 108% higher than those in the c.421CA genotype group and 131% higher than those in the c.421CC genotype group (P < or = 0.01). In MDCKII-ABCG2 cells, atorvastatin transport was increased in the apical direction as compared with vector control cells (transport ratio 1.9 +/- 0.1 vs. 1.1 +/- 0.1). These results indicate that the ABCG2 polymorphism markedly affects the pharmacokinetics of atorvastatin and, even more so, of rosuvastatin-potentially affecting the efficacy and toxicity of statin therapy.

ABCB1 haplotypes differentially affect the pharmacokinetics of the acid and lactone forms of simvastatin and atorvastatin.

ABCB1 haplotypes were determined in 534 healthy Finnish volunteers, of whom 24 participated in a pharmacokinetic study on simvastatin and atorvastatin. The frequencies of occurrence of haplotypes c.1236T-c.2677T-c.3435T and c.1236C-c.2677G-c.3435C were 42.7 and 34.4%, respectively. The simvastatin acid AUC(0-12h) was 60% larger, the atorvastatin AUC(0-infinity) 55% larger, and the atorvastatin half-life 24% longer in subjects with the ABCB1 TTT/TTT genotype (n = 12) than in those with the CGC/CGC genotype (n = 12) (P < 0.05), but there were no differences between the two genotypes with respect to the pharmacokinetics of the lactones of these drugs.