MECHANISMS OF DRUG INTERACTIONS AND REACTIVE METABOLITES

本项目所述研究的长期目标是 了解广泛使用的止痛药/解热药， 对乙酰氨基酚，与其他药物相互作用，并在 参与相互作用的分子水平酶。这一点很重要 避免由N-乙酰基-p- 苯醌亚胺，一种对乙酰氨基酚的活性代谢物， 几种细胞色素P450，代谢许多其他药物。结果 先前的研究暗示CYP 2 E1和CYP 2A 6是细胞色素P450的主要催化剂。 将对乙酰氨基酚氧化成其毒性醌亚胺和无毒醌亚胺 儿茶酚代谢物，分别，和抑制/诱导CYP 2 E1 其他药物，如异烟肼和乙醇，可以增加或减少风险， 对乙酰氨基酚引起的肝毒性取决于 与CYP 2 E1配体调节结果相关的摄入。我们 我建议继续我们的研究P450负责氧化的 对乙酰氨基酚的治疗 本建议的第一个具体目标是构建活性位点模型 与不同产品一致的CYP 2 E1和CYP 2A 6 这两种P450亚型对醌亚胺和邻苯二酚的选择性 对乙酰氨基酚的代谢物。将采用多层次的方法， 结合核磁共振顺磁弛豫研究的结果，同源性 和CoMFA建模，诱变实验，和机制研究- 基于灭活剂。 第二个具体目标是评估CYP 2 E1、CYP 3A 4和CYP 2 E3在细胞内的作用。 市场上肝细胞线粒体谷胱甘肽状态失调 对乙酰氨基酚对长期饮用乙醇的人的毒性。 这种相互作用已被认为是急性肝病的主要原因 失败在美国的相互作用是多方面的，建议 研究继续对在研究期间开始的这种相互作用进行评估。 最后一次授予期间。将使用大鼠模型来研究单独的 对乙酰氨基酚反应性代谢物形成变化的影响 肝细胞清除率和肝细胞线粒体GSH状态 损害将在人类志愿者中进行一系列研究， 确定CYP 2 E1和CYP 3A P450亚型对 对乙酰氨基酚剂量下体内对乙酰氨基酚反应性代谢物的形成 与适度饮酒的相互作用和影响有关， 酒精饮料和饥饿对这种临床综合症的影响。

The long-term objectives of the research described in this project are to understand mechanisms by which the widely used analgesic/antipyretic, acetaminophen, interacts with other drugs, and to characterize at the molecular level enzymes involved in the interactions. This is important to avoid life-threatening hepatic necrosis initiated by N-acetyl-p- benzoquinone imine, a reactive metabolite of acetaminophen formed by several cytochrome P450s that metabolize many other drugs. Results of previous studies implicate CYP2E1 and CYP2A6 as major catalysts in the oxidation of acetaminophen to its toxic quinoneimine and non-toxic catechol metabolites, respectively, and inhibition/induction of CYP2E1 by other drugs, such as isoniazid and ethanol, can increase or decrease risk of hepatotoxicity caused by acetaminophen depending on the time of ingestion relative to consequences of ligand regulation of CYP2E1. We propose to continue our studies of P450s responsible for the oxidation of acetaminophen in the next grant period. The first Specific Aim of this proposal is to construct active site models of CYP2E1 and CYP2A6 that are consistent with the different product selectivities of these two P450 isoforms for the quinoneimine and catechol metabolites of acetaminophen. A multi-tiered approach will be used that incorporate the results of NMR paramagnetic relaxation studies, homology and CoMFA modelling, mutagenesis experiments, and studies with mechanism- based inactivators. The second Specific Aim is to assess the roles of CYP2E1, CYP3A4 and dysregulation of hepatocyte mitochondrial glutathione status in the market toxicity of acetaminophen in individuals who chronically consume ethanol. This interaction has been suggested to be the leading cause of acute liver failure in the U.S. The interactions is multifaceted and the proposed studies continue an evaluation of this interaction initiated during the last grant period. A rat model will be used to investigate the separate effects of changes in acetaminophen reactive metabolite formation clearance and hepatocyte mitochondrial GSH status on hepatocellular damage. A series of studies will be conducted in human volunteers to determine the contribution of CYP2E1 and CYP3A P450 isoforms to acetaminophen reactive metabolite formation in vivo at acetaminophen doses relevant to the interaction and the effects that moderate drinking of alcoholic beverages and starvation have on this clinical syndrome.