The C3435T polymorphism in ABCB1 influences atorvastatin efficacy and muscle symptoms in a high-risk vascular cohort.

ABSTRACT

OBJECTIVE: The CC genotype of the C3435T polymorphism in ABCB1 is associated with increased P-glycoprotein expression, reduced low-density lipoprotein cholesterol (LDL-C) response to atorvastatin, and a reduced area-under-the-curve in pharmacokinetic studies. We sought to assess the relationship between 1) genotype and Atorvastatin efficacy, independently of variation in cholesterol metabolism and 2) genotype and myalgia. METHODS: High-risk vascular patients were genotyped and treated with atorvastatin 80 mg for 6 weeks. The lipid panel and percent LDL-C reduction with atorvastatin were related to C3435T genotype. Genotypes and allele frequency were assessed in patients with and without myalgia. RESULTS: A total of 117 patients were recruited and genotyped. Of these, 98 completed the study with adequate atorvastatin adherence, and 10 reported myalgia. T and C allele frequencies were 0.63 and 0.37, respectively. A 6-week course of atorvastatin (80 mg/day) reduced LDL-C by 58% ± 11% (mean ± SD). Patients with the CC genotype showed less LDL-C reduction with atorvastatin compared with the TT/TC genotype (53% vs 59%, respectively, P = .034), and this finding was independent of variation in cholesterol metabolism (P = .045 after correction for desmosterol and cholestanol/cholesterol ratio). The T allele was more frequent in patients with myalgia than those without (0.80 vs 0.62) and the C allele less frequent (0.20 vs 0.38, P = .043). CONCLUSION: In patients treated with atorvastatin, the CC genotype at the C3435T polymorphism in ABCB1 is associated with reduced atorvastatin efficacy independently of cholesterol metabolism. The T allele is more frequent and the C allele less frequent in patients with myalgia.