Wang Shuting, Tang Xiange, Yang Tingting, Xu Jiong, Zhang Jiaxin, Liu Xiaodong, Liu Li
a Center of Drug Metabolism and Pharmacokinetics, School of Pharmacy , China Pharmaceutical University , Nanjing , China.
Xenobiotica. 2019 Feb;49(2):161-168. doi: 10.1080/00498254.2018.1433902. Epub 2018 Feb 8.
Contributions of cytochrome P450 (CYP450) isoforms to drug metabolism are often predicted using relative activity factor (RAF) method, assuming RAF values were independent of probe. We aimed to report probe-dependent characteristic of RAF values using CYP3A4 or CYP2C9 probes. Metabolism of four CYP3A4 probes (testosterone, midazolam, verapamil and atorvastatin) and three CYP2C9 probes (tolbutamide, diclofenac and S-warfarin) in human liver microsomes (HLM) and cDNA-expressed recombinant CYP450 (Rec-CYP450) systems were characterized and RAF value was estimated as ratio of probe intrinsic clearance in HLM to that in Rec-CYP450. CYP450i contributions to metabolic reaction of a probe were predicted using other probes and compared with data from specific inhibitions. Contributions of CYP3A4 and CYP2C9 to metabolism of deoxypodophyllotoxin and nateglinide were also predicted. RAF values were dependent on probes, leading to probe-dependently predicted contributions. Predicted contributions of CYP3A4 to formations of 6β-hydroxytestosterone, 1'-hydroxymidazolam, norverapamil, ortho-hydroxyatorvastatin and para-hydroxyatorvastatin using other probes were 47.46-219.46%, 21.62-98.87%, 186.49-462.44%, 21.87-101.15% and 53.62-247.97%, respectively. Predicted contributions of CYP3A4 and CYP2C9 to nateglinide metabolism were 8.18-37.84% and 36.08-94.04%, separately. In conclusion, CYP450i contribution to drug metabolism in HLM estimated using RAF approach were probe-dependent. Therefore, contribution of each isoform must be confirmed by multiple probes.
细胞色素P450（CYP450）同工型对药物代谢的贡献通常使用相对活性因子（RAF）方法来预测，假定RAF值与探针无关。我们旨在报告使用CYP3A4或CYP2C9探针时RAF值的探针依赖性特征。对四种CYP3A4探针（睾酮、咪达唑仑、维拉帕米和阿托伐他汀）以及三种CYP2C9探针（甲苯磺丁脲、双氯芬酸和S-华法林）在人肝微粒体（HLM）和cDNA表达的重组CYP450（Rec-CYP450）系统中的代谢进行了表征，并将RAF值估计为HLM中探针固有清除率与Rec-CYP450中探针固有清除率的比值。使用其他探针预测CYP450同工型对一种探针代谢反应的贡献，并与特异性抑制数据进行比较。还预测了CYP3A4和CYP2C9对脱氧鬼臼毒素和那格列奈代谢的贡献。RAF值取决于探针，导致对贡献的预测具有探针依赖性。使用其他探针预测CYP3A4对6β-羟基睾酮、1'-羟基咪达唑仑、去甲维拉帕米、邻羟基阿托伐他汀和对羟基阿托伐他汀形成的贡献分别为47.46 - 219.46%、21.62 - 98.87%、186.49 - 462.44%、21.87 - 101.15%和53.62 - 247.97%。预测CYP3A4和CYP2C9对那格列奈代谢的贡献分别为8.18 - 37.84%和36.08 - 94.04%。总之，使用RAF方法估计的HLM中CYP450同工型对药物代谢的贡献具有探针依赖性。因此，每种同工型的贡献必须通过多种探针来确认。
