The P450 oxidoreductase (POR) rs2868177 and cytochrome P450 (CYP) 2B6*6 polymorphisms contribute to the interindividual variability in human CYP2B6 activity.

AIM: To investigate whether single-nucleotide polymorphisms (SNPs) in the P450 oxidoreductase (POR) gene were correlated with interindividual variations in cytochrome P450 (CYP) 2B6 activity. METHODS: Thirty-six healthy volunteers who tested CYP2B6 and POR polymorphisms were enrolled in the study. CYP2B6 activity was measured by bupropion hydroxylation with LC/MS/MS. The ratio of hydroxybupropion versus bupropion (AUC_hyd/AUC_bup) in terms of area under the time-concentration curve (AUC) was used to represent the CYP2B6 activity. RESULTS: The volunteers carrying CYP2B6*1/*1 showed a significantly higher mean AUC_hyd/ AUC_bup than those CYP2B6*1/*6 and CYP2B6*6/*6 variants (15.66 ± 1.65 vs. 9.25 ± 1.92, P = 0.008 and 15.66 ± 1.65 vs. 8.21 ± 1.74, P = 0.006, respectively). POR rs2868177 (6593 A > G) AA homozygotes showed a significantly lower mean AUC_hyd/ AUC_bup than that of POR rs2868177 AG heterozygotes or GG homozygotes (8.13 ± 1.37 vs. 12.15 ± 2.97, P = 0.005 and 8.13 ± 1.37 vs. 17.59 ± 3.25, P = 0.001, respectively). Moreover, POR rs2868177 AG heterozygotes and GG homozygotes showed a significantly increased mean AUC_hyd/AUC_bup than AA homozygotes in the CYP2B6*1/*1 and CYP2B6*6 carriers (16.40 ± 2.01 vs. 12.40 ± 1.45, P = 0.006 and 10.65 ± 1.47 vs. 6.54 ± 1.25, P = 0.004, respectively). Meanwhile, a strong correlation between the genetic variations (POR rs2868177 and CYP2B6*6) and AUC_hyd/ AUC_bup was found (P = 0.009 and P = 0.001, respectively). There was no significant difference in the mean AUC_hyd/AUC_bup among different POR *28 genotypes (P > 0.05). CONCLUSION: POR rs2868177 and CYP2B6*6 variants contribute to the interindividual variability in human CYP2B6 activity, which may affect the disposition and interaction of other CYP2B6 substrate drugs.

Influence of PTGS1, PTGFR, and MRP4 genetic variants on intraocular pressure response to latanoprost in Chinese primary open-angle glaucoma patients.

PURPOSE: The purpose of this study is to evaluate the association between variants in prostaglandin-endoperoxide synthase 1 (PTGS1), prostaglandin F (2α) receptor (PTGFR), and multidrug resistance protein 4 (MRP4) genes and intraocular pressure (IOP) response to latanoprost in Chinese patients with primary open-angle glaucoma (POAG). METHODS: The IOP response to latanoprost was evaluated by percent IOP reduction (%ΔIOP) in the treated eye with the formula %ΔIOP = (Baseline IOP values - IOP values posttreatment) / Baseline IOP values × 100 %. Polymorphisms in PTGS1 (rs3842787 and rs10306114), PTGFR (rs3753380 and rs3766355), and MRP4 (rs11568658 and rs11568668) genes were detected by direct DNA sequencing. The differences among %ΔIOP of genotypes or haplotypes were obtained by use of the Mann-Whitney U test. Association analyses were performed by multiple linear regression analysis. RESULTS: Latanoprost were prescribed to 63 subjects, 60 of which met the inclusion/exclusion criteria for the current study. Notably, the %ΔIOP in the rs11568658 GT heterozygous genotype was 10.4 %ΔIOP lower than that of GG homozygous wild-type on day 7 (15.7 ± 2.52 vs. 26.1 ± 2.88, P=0.003), and the corresponding results in the rs10306114 AG heterozygous genotype and AT haplotype constructed by rs3753380 and rs3766355 on day 7 were 7.2 and 10.3 %ΔIOP (P<0.05). Interestingly, similar results were also observed on day 30 (P=0.008, P=0.006, and P=0.002, respectively). Multiple regression analysis showed that heterozygous genotypes of rs10306114, rs11568658, and carrier of AT haplotype were significantly correlated with the lower %ΔIOP. On day 30, the above variations explained 9.9, 10.7, and 17.7 % of the total variability of %ΔIOP in the Chinese POAG patients, respectively. CONCLUSION: rs10306114, rs3753380, rs3766355, and rs11568658 single-nucleotide polymorphisms (SNPs) correlate with a response to latanoprost treatment in patients with POAG. These SNPs may be important determinants of variability in response to latanoprost.