Genomic and drug-drug interaction mechanisms of interindividual variability in drug disposition

项目摘要/摘要 药物反应的很大程度的个体间差异经常危及药物安全和 功效。我研究的长期目标是从机制上和临床上理解这种变异性和 然后是个性化的药物治疗。我的研究主要由NIGMS资助，主要关注药物的变化 药物动力学由1)遗传的药物处置差异和2)不可预测的药物-药物 交互作用(DDIS)。这项工作产生了新的和新的药物处置机制，并确定了基因 以及导致药物和/或活性代谢物暴露和影响的个体间差异的DDI因素。 开发了新的体外和临床表型分析工具、基因组生物标记物和LC/MS/MS方法 这极大地促进了药物处置科学的发展，并促进了合作和全球研究 努力。例子包括修订FDA用于Eefavirenz的包装插页，开发剂量 关于Eefavirenz和CYP2B6的指南和立场文件，以及Eefavirenz作为体外和体内探针的使用 CYP2B6活性的变化。然而，对药物个体间差异的机制的了解还不完全 对许多其他临床重要药物的处置仍然存在，并继续影响实施 最大的药效和最小的毒性。这一知识差距是这款Mira应用程序的重点。 1)药物处置的遗传变异性和DDIS对药物暴露和效应的联合效应 很少有人研究。Eefavirenz(一种CYP2B6底物，治疗HIV的关键药物)诱导 其抑制肝脏细胞色素P1A2的作用依赖于细胞色素P450受体6的基因型别。我们假设 遗传变异和DDIS的相互作用是受试者之间药物处置和药物处置差异的关键驱动因素 效果。在健康志愿者中，对CYP2B6变异进行基因分型后，立体选择性的倾向和效果(例如， 美沙酮(一种CYP2B6底物)及其作用(收缩和舒张期血液 替扎尼定(一种敏感的CYP1A2底物)的压力)将在基线和预处理后进行测定 Eefavirenz(600 mg/d，共17天)。2)UGT在肝外组织中的表达存在差异，但 它们在药物代谢中的作用尚不完全清楚。在我们最近发表的多洛替格雷的基础上 (UGT1A1和UGT1A9底物)，我们将检验以下假设：调节肝外代谢 UGT衬底有助于UGT衬底曝光的可变性。深入的体外动力学和 抑制研究将对来自UGT基因分型的人肝、肠和 肾组织。3)一些临床上观察到的复杂DDIS在现有知识的基础上是不可预测的。 基于我们在安非他酮-细胞色素P450-D6相互作用方面的工作，我们建议进行体外DDI研究，以确定 临床观察的DDIS的机制基础，侧重于循环代谢物/立体异构体和较差的 了解新陈代谢途径。适当的电子计算机方法将补充我们的研究。结果将会是 增强我们个性化药物治疗的能力。

Project Summary/Abstract Large degree of interindividual variability in drug response frequently compromises drug safety and efficacy. The long-term goal of my research is a mechanistic and clinical understanding of this variability and then personalized drug therapy. My research, funded mainly by NIGMS, has focused on the changes in drug pharmacokinetics due to both 1) inherited differences in drug disposition and 2) unpredictable drug-drug interactions (DDIs). This work produced new and novel mechanisms of drug disposition and identified genetic and DDI factors responsible for interindividual variability in drug and/or active metabolite exposure and effects. Novel in vitro and clinical phenotyping tools, genomic biomarkers and LC/MS/MS methods were developed that significantly advanced the science of drug disposition and stimulated collaborative and worldwide research endeavors. Examples include revision of the FDA package insert for efavirenz, development of dosing guidelines and position papers on efavirenz and CYP2B6, and the use of efavirenz as in vitro and in vivo probe of CYP2B6 activity. Yet, incomplete understanding of the mechanisms for interindividual variability in drug disposition persists for many other clinically important drugs and continues to compromise the implementation of maximum drug efficacy with minimal toxicity. This knowledge gap is the focus of this MIRA application. 1) The combined effect of genetic variability in drug disposition and DDIs on drug exposure and effect has rarely been studied. Efavirenz (a CYP2B6 substrate and a critical drug for the treatment of HIV) induces hepatic CYP2B6 and inhibits hepatic CYP1A2 in CYP2B6 genotype-dependent fashion. We hypothesize that interplay of genetic variations and DDIs is a key driver of intersubject differences in drug disposition and effect. In healthy volunteers genotyped for CYP2B6 variants, the stereoselective disposition and effect (e.g., pupil diameter) of methadone (a CYP2B6 substrate) and the disposition and effect (systolic and diastolic blood pressures) of tizanidine (a sensitive CYP1A2 substrate) will be determined at baseline and after pretreatment with efavirenz (600 mg/day PO for 17 days). 2) UGTs are differentially expressed in extrahepatic tissues, but their role in in drug metabolism is incompletely understood. Building on our recent publication with dolutegravir (a UGT1A1 and UGT1A9 substrate), we will test the hypothesis that modulation of extrahepatic metabolism of UGT substrates contributes to the variability in exposure of UGT substrates. In-depth in vitro kinetic and inhibition studies will be performed in microsomes derived from UGT genotyped human hepatic, intestinal and kidney tissues. 3) Some clinically observed complex DDIs are unpredictable based on current knowledge. Capitalizing on our work with bupropion-CYP2D6 interaction, in vitro DDI studies are proposed to identify the mechanistic basis of clinically observed DDIs, focusing on circulating metabolites/stereoisomers and less well- understood metabolic pathways. Appropriate in silico approaches will complement our studies. The results will enhance our ability to personalize drug therapy.