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

项目总结/摘要 药物反应的个体间差异性较大，经常危及药物安全性， 功效我的研究的长期目标是对这种变异性的机制和临床理解， 然后是个性化药物治疗我的研究主要由NIGMS资助，主要集中在药物的变化上， 由于1）药物分布的遗传差异和2）不可预测的药物-药物 相互作用（DDI）。这项工作产生了新的和新颖的药物处置机制，并确定了遗传 和DDI因素，负责药物和/或活性代谢物暴露和效应的个体间变异性。 开发了新的体外和临床表型分析工具、基因组生物标志物和LC/MS/MS方法 这极大地推进了药物处置科学，并刺激了全球范围内的合作研究， 努力例如，修订了依非韦伦的FDA药品说明书， 关于依法韦仑和CYP 2B 6的指南和立场文件，以及依法韦仑作为体外和体内探针的用途 CYP 2B 6活性。然而，对药物个体间变异机制的不完全理解， 许多其他临床重要药物的处置持续存在，并继续影响实施 最大的药效和最小的毒性。这种知识差距是这个MIRA应用程序的重点。 1)药物处置的遗传变异性和DDI对药物暴露和效应的综合影响， 很少被研究。依法韦仑（CYP 2B 6底物和治疗HIV的关键药物）诱导 肝CYP 2B 6，并以CYP 2B 6基因型依赖性方式抑制肝CYP 1A 2。我们假设 遗传变异和DDI的相互作用是药物处置中受试者间差异的关键驱动因素， 效果在CYP 2B 6变体基因分型的健康志愿者中，立体选择性分布和作用（例如， 瞳孔直径）的美沙酮（CYP 2B 6底物）和处置和影响（收缩期和舒张期血液 将在基线和预处理后测定替扎尼定（一种敏感的CYP 1A 2底物）的压力 依非韦仑（600 mg/天PO，持续17天）。2)UGT在肝外组织中差异表达，但 它们在药物代谢中的作用还不完全清楚。基于我们最近发表的关于度鲁特韦的文章 （UGT 1A 1和UGT 1A 9底物），我们将检验以下假设： UGT底物有助于UGT底物暴露的可变性。深入的体外动力学和 抑制研究将在来自UGT基因分型的人肝、肠和 肾脏组织3)根据目前的知识，一些临床观察到的复杂DDI是不可预测的。 利用我们的工作与安非他酮CYP 2D 6相互作用，在体外DDI研究提出，以确定 临床观察到的DDI的机制基础，重点是循环代谢物/立体异构体， 了解代谢途径。适当的计算机模拟方法将补充我们的研究。结果将 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.