MECHANISMS OF INHIBITORY DRUG INTERACTIONS

抑制性药物相互作用的机制

• 批准号: 6701459
• 负责人: KENT L KUNZE
• 金额: $ 20.91万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6701459
• 关键词: active sites; chemical synthesis; cytochrome P450; drug interactions; drug metabolism; electrospray ionization mass spectrometry; enzyme activity; enzyme inhibitors; enzyme mechanism; fluconazole; fluvoxamine; itraconazole; liver cells; microsomes; oxidation reduction reaction; tissue /cell culture

The long-term objective of the research described in this grant proposal is to better understand metabolism-based drug-drug interactions that are underpredicted from in vitro data. This is important because underprediction of effect has negative consequences for drug therapy and the development of new drugs. It is also important because these outliers represent a significant fraction of clinically relevant drug-drug interactions. An in-depth understanding of why predictions fail should improve predictive efforts. The interactions we propose to study are drawn from the larger class of interactions that appear to arise as the result concentrative cell uptake and/or metabolites of the interactant drug. Predictive quality is degraded because the magnitude of the inhibition depends not only on the concentration of the interactant drug at the active site, but also on the activity of the enzymes involved in converting the drug to the proximate inhibitory metabolite as well as the mechanism of metabolite inhibition. The first section of this proposal investigates two potent inhibitors of P450-catalyzed drug metabolism, fluvoxamine and itraconazole, who's in vivo effects are 10- to 100- fold higher than predicted. Fluvoxamine causes potent and differential inhibition of at least 4 important human P450' s in vivo. Aims 1-3 will identify the sources of the underprediction for each enzyme by examining the importance of concentrative uptake as well as direct inhibitory effects of fluvoxamine, itraconazole and their major metabolites on enzyme activities in microsomal preparations and human hepatocytes. The finding that time dependent, persistent inhibition of CYP3A4 activity by itraconazole is observed in microsomes and intestinal cells further suggests that itraconazole is a mechanism-based inhibitor of this important enzyme. Aim 4 will assess if other factors, such as concentrative uptake, are required to fully explain the effect of itraconazole and, if so, to identify them. The second section of the proposal addresses the propensity of alkylamine containing drugs to elicit irreversible inhibition of enzyme activity via formation of MI complexes in vivo and in vitro. This process requires that the alkylamine undergo as many as 4 rounds of oxidation to the corresponding C-nitroso metabolite prior to the inhibitory event. This very complex type of inhibition has not been fully characterized and a deeper understanding of the underlying mechanisms is critical for meaningful and reproducible in vitro-in vivo predictions of inhibitory effect. Aims 5 and 6 of this proposal set out to fully describe the kinetics of the system and evaluate the limits and advantages of a less complex empirical approach.

该赠款提案中描述的研究的长期目标是更好地了解基于代谢的药物 - 药物相互作用，这些相互作用是从体外数据中预测的。这很重要，因为不足的效应对药物治疗和新药的发展产生负面影响。这也很重要，因为这些异常值代表了临床上相关的药物相互作用的很大一部分。深入了解为什么 预测失败应改善预测努力。我们建议研究的相互作用是从较大的相互作用类别中得出的，这些相互作用似乎是由于相互作用药物的浓度细胞摄取和/或代谢产物而产生的。预测质量会降低，因为抑制的大小不仅取决于活性部位相互作用药物的浓度，还取决于将药物转化为转化为 近端抑制性代谢产物以及代谢产物抑制的机理。该提案的第一部分调查了两个有效的P450催化药物代谢的抑制剂： 体内效应的氟氟氧胺和伊曲康唑高于预测的10至100倍。氟氟乙烷在体内至少4个重要的人P450的有效和差异抑制作用。 AIMS 1-3将通过检查浓度摄取的重要性以及氟伐曲他胺，Itraconazole及其主要代谢物对微粒细胞制剂和酶活性的主要代谢产生的直接抑制作用来确定每种酶预测不足的来源。 人肝细胞。在微粒体和肠细胞中观察到时间依赖性，持续抑制CYP3A4活性的发现进一步表明，伊曲康唑是基于机制的这种重要酶的抑制剂。 AIM 4将评估是否需要其他因素（例如浓度吸收）来充分解释伊曲康唑的效果，并确定它们。该提案的第二部分介绍了含有药物的烷基胺的倾向，从而通过体内和体外形成MI复合物，从而引发不可逆性的酶活性。该过程要求在抑制事件发生之前，烷基胺对相应的C-硝基代谢产物进行多达4轮氧化。这种非常复杂的抑制类型尚未完全表征，对 潜在的机制对于有意义的和可重现的体内体内预测至关重要。该提案的目标5和6旨在充分描述系统的动力学，并评估不太复杂的经验方法的局限性和优势。