Pharmacokinetic Sciences, Novartis Pharma AG, Basel, Switzerland
Pharmacokinetic Sciences, Novartis Pharma AG, Basel, Switzerland.
Drug Metab Dispos. 2024 Apr 16;52(5):345-354. doi: 10.1124/dmd.123.001597.
It is common practice in drug discovery and development to predict in vivo hepatic clearance from in vitro incubations with liver microsomes or hepatocytes using the well-stirred model (WSM). When applying the WSM to a set of approximately 3000 Novartis research compounds, 73% of neutral and basic compounds (extended clearance classification system [ECCS] class 2) were well-predicted within 3-fold. In contrast, only 44% (ECCS class 1A) or 34% (ECCS class 1B) of acids were predicted within 3-fold. To explore the hypothesis whether the higher degree of plasma protein binding for acids contributes to the in vitro-in vivo correlation (IVIVC) disconnect, 68 proprietary compounds were incubated with rat liver microsomes in the presence and absence of 5% plasma. A minor impact of plasma on clearance IVIVC was found for moderately bound compounds (fraction unbound in plasma [fu] ≥1%). However, addition of plasma significantly improved the IVIVC for highly bound compounds (fu <1%) as indicated by an increase of the average fold error from 0.10 to 0.36. Correlating fu with the scaled unbound intrinsic clearance ratio in the presence or absence of plasma allowed the establishment of an empirical, nonlinear correction equation that depends on fu Taken together, estimation of the metabolic clearance of highly bound compounds was enhanced by the addition of plasma to microsomal incubations. For standard incubations in buffer only, application of an empirical correction provided improved clearance predictions. SIGNIFICANCE STATEMENT: Application of the well-stirred liver model for clearance in vitro-in vivo extrapolation (IVIVE) in rat generally underpredicts the clearance of acids and the strong protein binding of acids is suspected to be one responsible factor. Unbound intrinsic in vitro clearance (CL) determinations using rat liver microsomes supplemented with 5% plasma resulted in an improved IVIVE. An empirical equation was derived that can be applied to correct CL-values in dependance of fraction unbound in plasma (fu) and measured CL in buffer.
在药物发现和开发中，通常使用完全混合模型（WSM）从肝微粒体或肝细胞的体外孵育中预测体内肝清除率。当将 WSM 应用于大约 3000 种诺华研究化合物的集合时，73%的中性和碱性化合物（扩展清除分类系统[ECCS]第 2 类）在 3 倍内得到了很好的预测。相比之下，只有 44%（ECCS 第 1A 类）或 34%（ECCS 第 1B 类）的酸在 3 倍内得到了预测。为了探讨假设，即酸的更高程度的血浆蛋白结合是否导致了体外-体内相关性（IVIVC）的脱节，将 68 种专有化合物与大鼠肝微粒体在有或没有 5%血浆的情况下孵育。发现对于中度结合的化合物（血浆中未结合的分数[fu]≥1%），血浆对清除率 IVIVC 的影响较小。然而，对于高度结合的化合物（fu<1%），添加血浆显著改善了 IVIVC，平均倍数误差从 0.10 增加到 0.36。将 fu 与存在或不存在血浆时的未结合内在清除率的比例相关联，允许建立一个经验性的、非线性的校正方程，该方程取决于 fu。总的来说，通过向微粒体孵育中添加血浆，增强了对高度结合化合物的代谢清除率的估计。对于仅在缓冲液中进行的标准孵育，应用经验校正可提供更好的清除率预测。意义陈述：在大鼠中，应用完全混合的肝脏模型进行清除率的体外-体内外推（IVIVE）通常会低估酸的清除率，并且怀疑酸的强蛋白结合是一个负责因素。使用大鼠肝微粒体补充 5%血浆进行未结合的内在体外清除率（CL）测定导致 IVIVE 得到改善。得出了一个经验公式，可以根据血浆中非结合部分（fu）和测量的缓冲液中的 CL 来校正 CL 值。
