Pelkonen Olavi, Tolonen Ari, Korjamo Timo, Turpeinen Miia, Raunio Hannu
Department of Pharmacology and Toxicology, PO Box 5000, FIN-90014, University of Oulu, Finland.
Bioanalysis. 2009 May;1(2):393-414. doi: 10.4155/bio.09.32.
'It is better to be useful than perfect'. This review attempts to critically cover and assess the currently available approaches and tools to answer the crucial question: Is it possible (and if it is, to what extent is it possible) to predict in vivo metabolites and their abundances on the basis of in vitro and preclinical animal studies? In preclinical drug development, it is possible to produce metabolite patterns from a candidate drug by virtual means (i.e., in silico models), but these are not yet validated. However, they may be useful to cover the potential range of metabolites. In vitro metabolite patterns and apparent relative abundances are produced by various in vitro systems employing tissue preparations (mainly liver) and in most cases using liquid chromatography-mass spectrometry analytical techniques for tentative identification. The pattern of the metabolites produced depends on the enzyme source; the most comprehensive source of drug-metabolizing enzymes is cultured human hepatocytes, followed by liver homogenate fortified with appropriate cofactors. For specific purposes, such as the identification of metabolizing enzyme(s), recombinant enzymes can be used. Metabolite data from animal in vitro and in vivo experiments, despite known species differences, may help pinpoint metabolites that are not apparently produced in in vitro human systems, or suggest alternative experimental approaches. The range of metabolites detected provides clues regarding the enzymes attacking the molecule under study. We also discuss established approaches to identify the major enzymes. The last question, regarding reliability and robustness of metabolite extrapolations from in vitro to in vivo, both qualitatively and quantitatively, cannot be easily answered. There are a number of examples in the literature suggesting that extrapolations are generally useful, but there are only a few systematic and comprehensive studies to validate in vitro-in vivo extrapolations. In conclusion, extrapolation from preclinical metabolite data to the in vivo situation is certainly useful, but it is not known to what extent.
“有用胜于完美”。本综述旨在批判性地涵盖和评估当前可用的方法和工具，以回答关键问题：基于体外和临床前动物研究，是否有可能（如果可能，在何种程度上可能）预测体内代谢物及其丰度？在临床前药物开发中，可以通过虚拟手段（即计算机模拟模型）从候选药物中生成代谢物模式，但这些模式尚未得到验证。然而，它们可能有助于涵盖代谢物的潜在范围。体外代谢物模式和表观相对丰度是通过各种体外系统产生的，这些系统采用组织制剂（主要是肝脏），并且在大多数情况下使用液相色谱 - 质谱分析技术进行初步鉴定。产生的代谢物模式取决于酶源；药物代谢酶最全面的来源是培养的人肝细胞，其次是添加了适当辅因子的肝脏匀浆。出于特定目的，例如鉴定代谢酶，可以使用重组酶。尽管存在已知的物种差异，但来自动物体外和体内实验的代谢物数据可能有助于找出在体外人体系统中未明显产生的代谢物，或提出替代实验方法。检测到的代谢物范围提供了有关攻击所研究分子的酶的线索。我们还讨论了确定主要酶的既定方法。关于从体外到体内代谢物推断的可靠性和稳健性，无论是定性还是定量方面，最后这个问题都不容易回答。文献中有许多例子表明推断通常是有用的，但只有少数系统和全面的研究来验证体外 - 体内推断。总之，从临床前代谢物数据推断体内情况肯定是有用的，但具体程度尚不清楚。
