Clinical Pharmacology and Pharmacometrics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan (A.Y., S.A., S.H., Y.T., N.H., K.T., H.S., A.H.); Toxicology & DMPK Research Department, Teijin Pharma Limited, Tokyo, Japan (S.A., Y.Sa., N.O., M.K., T.I.); Department of Regulatory Science, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan (Y.Sh.); and Chromosome Engineering Research Center (Y.K.) and Division of Genome and Cellular Functions, Department of Molecular and Cellular Biology, School of Life Science, Faculty of Medicine (Y.K.), Tottori University, Tottori, Japan.
Clinical Pharmacology and Pharmacometrics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan (A.Y., S.A., S.H., Y.T., N.H., K.T., H.S., A.H.); Toxicology & DMPK Research Department, Teijin Pharma Limited, Tokyo, Japan (S.A., Y.Sa., N.O., M.K., T.I.); Department of Regulatory Science, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan (Y.Sh.); and Chromosome Engineering Research Center (Y.K.) and Division of Genome and Cellular Functions, Department of Molecular and Cellular Biology, School of Life Science, Faculty of Medicine (Y.K.), Tottori University, Tottori, Japan
Drug Metab Dispos. 2023 Mar;51(3):318-328. doi: 10.1124/dmd.122.000907. Epub 2022 Dec 7.
Drug absorption from the gastrointestinal tract is often restricted by efflux transport by P-glycoprotein (P-gp) and metabolism by CYP3A4. Both localize in the epithelial cells, and thus, their activities are directly affected by the intracellular drug concentration, which should be regulated by the ratio of permeability between apical (A) and basal (B) membranes. In this study, using Caco-2 cells with forced expression of CYP3A4, we assessed the transcellular permeation of A-to-B and B-to-A directions and the efflux from the preloaded cells to both sides of 12 representative P-gp or CYP3A4 substrate drugs and obtained the parameters for permeabilities, transport, metabolism, and unbound fraction in the enterocytes (f) using simultaneous and dynamic model analysis. The membrane permeability ratios for B to A (R) and f varied by 8.8-fold and by more than 3000-fold, respectively, among the drugs. The R values for digoxin, repaglinide, fexofenadine, and atorvastatin were greater than 1.0 (3.44, 2.39, 2.27, and 1.90, respectively) in the presence of a P-gp inhibitor, thus suggesting the potential involvement of transporters in the B membrane. The Michaelis constant for quinidine for P-gp transport was 0.077 µM for the intracellular unbound concentration. These parameters were used to predict overall intestinal availability (FF) by applying an intestinal pharmacokinetic model, advanced translocation model (ATOM), in which permeability of A and B membranes accounted separately. The model predicted changes in the absorption location for P-gp substrates according to its inhibition, and FF values of 10 of 12 drugs, including quinidine at varying doses, were explained appropriately. SIGNIFICANCE STATEMENT: Pharmacokinetics has improved predictability by identifying the molecular entities of metabolism and transport and by using mathematical models to appropriately describe drug concentrations at the locations where they act. However, analyses of intestinal absorption so far have not been able to accurately consider the concentrations in the epithelial cells where P-glycoprotein and CYP3A4 exert effects. In this study, the limitation was removed by measuring the apical and basal membrane permeability separately and then analyzing these values using new appropriate models.
药物从胃肠道吸收通常受到 P-糖蛋白（P-gp）外排转运和 CYP3A4 代谢的限制。这两者都定位于上皮细胞中，因此，它们的活性直接受到细胞内药物浓度的影响，而细胞内药物浓度应通过顶端（A）和基底（B）膜之间的通透性比值来调节。在这项研究中，我们使用 CYP3A4 强制表达的 Caco-2 细胞，评估了 12 种代表性 P-gp 或 CYP3A4 底物药物从 A 到 B 和 B 到 A 方向的跨细胞渗透以及从预加载细胞向两侧的外排，并使用同时和动态模型分析获得了肠细胞（f）中的渗透性、转运、代谢和未结合分数的参数。在药物中，B 到 A 的膜通透性比值（R）和 f 分别变化了 8.8 倍和 3000 多倍。在 P-gp 抑制剂存在的情况下，地高辛、瑞格列奈、非索非那定和阿托伐他汀的 R 值大于 1.0（分别为 3.44、2.39、2.27 和 1.90），因此表明转运体可能参与了 B 膜。P-gp 转运的 quindine 的米氏常数为 0.077 µM，对于细胞内未结合浓度。这些参数用于通过应用肠药代动力学模型（ATOM）来预测整体肠可利用度（FF），其中单独考虑了 A 和 B 膜的通透性。该模型根据其抑制作用预测了 P-gp 底物的吸收位置的变化，并且 12 种药物中的 10 种，包括不同剂量的 quindine，其 FF 值得到了合理的解释。意义声明：药代动力学通过识别代谢和转运的分子实体，并使用数学模型来适当地描述药物在其作用部位的浓度，从而提高了预测能力。然而，到目前为止，肠道吸收的分析还不能准确地考虑到 P-糖蛋白和 CYP3A4 发挥作用的上皮细胞中的浓度。在这项研究中，通过分别测量顶端和基底膜的通透性，并使用新的适当模型分析这些值，消除了这一限制。
