Bednarczyk Dallas, Sanghvi Menaka V
Pharmacokinetic Sciences, Novartis Institutes of BioMedical Science, Cambridge, MA, USA.
Xenobiotica. 2020 Jul;50(7):753-760. doi: 10.1080/00498254.2019.1691284. Epub 2019 Nov 15.
permeability assessment tools, like PAMPA, Caco-2, and MDCK, are frequently used to assess permeability and provide input in to various classification systems. Frequently, the measured recovery values in permeability assays are poor. Poor recovery may be a result of lysosomal trapping of compound. It was hypothesized that a relationship existed between diminished assay recovery of compound due to lysosomal trapping and underestimation of the P value.To examine this hypothesis, a series of experiments were conducted measuring cellular accumulation, percent recovery, and permeability in the absence or presence of an inhibitor of the V-type H-ATPase, bafilomycin A1, to determine if a quantifiable relationship between lysosomal trapping, recovery, and permeability existed.Displacing compounds from lysosomes using bafilomycin A1 resulted in an improved compound recovery in the assay and a corresponding elevated permeability, where for each 10% loss in recovery, a P underestimate of ∼2.2 × 10 cm/s was observed. The findings highlight the potential for compound misclassification in various classification systems when assay recovery is not considered. Consideration of lysosomal trapping in the context of permeability assays may yield permeability values more reflective of the intrinsic permeability and the appropriate permeability classification.
通透性评估工具，如平行人工膜渗透实验（PAMPA）、人结肠腺癌细胞系（Caco-2）和犬肾细胞系（MDCK），经常用于评估通透性，并为各种分类系统提供数据输入。通常，通透性实验中测得的回收率很低。回收率低可能是由于化合物被溶酶体捕获。据推测，由于溶酶体捕获导致化合物实验回收率降低与P值被低估之间存在关联。为了验证这一假设，进行了一系列实验，测量在有无V型H⁺-ATP酶抑制剂巴弗洛霉素A1的情况下细胞摄取、回收率和通透性，以确定溶酶体捕获、回收率和通透性之间是否存在可量化的关系。使用巴弗洛霉素A1将化合物从溶酶体中置换出来，导致实验中化合物回收率提高，相应地通透性也升高，即回收率每降低10%，观察到P值低估约2.2×10⁻²cm/s。这些发现突出了在不考虑实验回收率时，各种分类系统中化合物可能被错误分类的可能性。在通透性实验中考虑溶酶体捕获可能会得出更能反映内在通透性和合适通透性分类的通透性值。
