MECHANISMS OF DRUG INTERACTIONS AND REACTIVE METABOLITES

本项目所描述的研究的长期目标是 了解广泛使用的止痛剂/退热剂， 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的酶。这一点很重要 避免N-乙酰-p-磷酸引起的危及生命的肝坏死 对乙酰氨基酚的活性代谢物苯醌亚胺，由 代谢许多其他药物的几种细胞色素P450。结果： 先前的研究表明，细胞色素P450-2E_1和细胞色素P450_2-A_6是 对乙酰氨基酚氧化为其毒性和无毒的喹诺亚胺 儿茶酚代谢物对细胞色素P4502的抑制/诱导作用 其他药物，如异烟肼和乙醇，可以增加或降低风险。 对乙酰氨基酚引起的肝毒性的影响取决于时间 摄取与CYP2E1配体调节的后果相关。我们 建议继续我们对P450负责氧化的研究 对乙酰氨基酚在下一批资助期。 该建议的第一个具体目标是构建活动站点模型 与不同产品一致的CYP2E1和CYP2A6 这两种P450亚型对苯二亚胺和儿茶酚的选择性 对乙酰氨基酚的代谢物。将使用多层方法， 结合核磁共振顺磁松弛研究的结果，同源 和CoMFA模型，诱变实验，以及机理研究- 以灭活剂为基础。 第二个具体目标是评估细胞色素P450_2E_1、细胞色素P450_3A_4和细胞色素P4的作用。 市场上肝细胞线粒体谷胱甘肽状态的失调 对乙酰氨基酚对长期使用乙醇的人的毒性。 这种相互作用被认为是急性肝病的主要原因。 在美国的失败。互动是多方面的，建议的 研究继续对这种相互作用进行评估 最后一次授权期。将使用大鼠模型来研究分离的 对乙酰氨基酚反应性代谢物形成的影响 肝细胞清除与肝细胞线粒体GSH状态的关系 损坏。将在人类志愿者中进行一系列研究，以 确定细胞色素P450亚型和细胞色素P450亚型对细胞色素P450的作用 扑热息痛剂量下体内反应性代谢产物的形成 与适量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征有影响。

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.