We explore a virtual experiment strategy to discover plausible mechanism-based explanations for frequently inaccurate predictions of hepatic drug clearance made using established in vitro-in vivo extrapolation methods. We describe a three-protocol plan that uses validated software analogs of real in vitro and in vivo systems constructed using a common set of objects, components, spaces, and methods. Both systems utilize identical quasi autonomous hepatocyte analogs containing enzyme-like objects. We parameterize concrete mobile objects (virtual compounds) to simulate the referent drugs disposition and removal characteristics in vitro and in vivo. The goal of Protocol one (Protocol two) is that measures of virtual compound removal using the in vitro analog (in vivo analog) map directly to the measurements used to compute intrinsic clearance (in vivo hepatic clearance). Protocol three, the focus of this work, requires achieving an essential cross-system validation target. For a subset of virtual compounds, measurements of unbound compounds entering hepatocytes (and their subsequent removal) during virtual in vitro experiments will directly predict corresponding measures made during virtual in vivo experiments. We study four highly permeable virtual compounds when their unbound fraction is fixed at one of seven values (0.05-1.0). Results span the range of hepatic extraction ratios. We achieve the cross-system validation target in 15 cases. In the other 13 cases, explanations of the in vitro-in vivo differences in disposition and removal trace to differences in compound-hepatocyte access within the two analogs during execution. The hepato-mimetic structural organization of hepatocytes within the in vivo analog, which is absent within the in vitro analog, is the determining factor. The results taken together support the feasibility of using the three-protocol plan to help explain observed in vitro-in vivo extrapolation discrepancies. We conjecture that, for some cases, the model mechanism-based explanations of discrepancies described herein will have wet-lab counterparts.

中文翻译：

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利用虚拟实验增进对涉及肝清除率体内-体外预测的差异的理解

我们探索一种虚拟实验策略，以发现使用建立的体外-体内外推方法对肝药物清除率进行频繁不准确预测的基于合理机制的解释。我们描述了一个三协议计划，该计划使用经过验证的类似体内和体外系统的软件类似物，该系统使用一组通用的对象，组件，空间和方法构建。两种系统都利用包含酶样物的相同的准自主肝细胞类似物。我们参数化具体的移动对象（虚拟化合物），以模拟相关药物在体内和体外的处置特征。方案一（方案二）的目标是，使用体外类似物（体内类似物）去除虚拟化合物的措施直接映射到用于计算固有清除率（体内肝清除率）的措施。协议三是这项工作的重点，要求实现基本的跨系统验证目标。对于虚拟化合物的子集，在虚拟体外实验过程中进入肝细胞的未结合化合物的测量（及其后续去除）将直接预测在虚拟体内实验过程中进行的相应测量。当它们的未结合分数固定为七个值（0.05-1.0）之一时，我们研究了四个高渗透性虚拟化合物。结果涵盖了肝提取率的范围。我们在15个案例中实现了跨系统验证的目标。在其他13种情况下，体内和体外配置和去除差异的解释可追溯到执行过程中两个类似物中化合物-肝细胞通路的差异。决定性因素是体内类似物中不存在的肝细胞的仿肝结构组织。综合起来的结果支持使用三协议计划来帮助解释观察到的体外-体内外推差异的可行性。我们推测，在某些情况下，此处描述的基于模型机制的差异解释将具有湿实验室的对应内容。体外类似物中缺少的是决定因素。综合起来的结果支持使用三协议计划来帮助解释观察到的体外-体内外推差异的可行性。我们推测，在某些情况下，此处描述的基于模型机制的差异解释将具有湿实验室的对应内容。体外类似物中缺少的是决定因素。综合起来的结果支持使用三协议计划来帮助解释观察到的体外-体内外推差异的可行性。我们推测，在某些情况下，此处描述的基于模型机制的差异解释将具有湿实验室的对应内容。