Kietic analysis and evaluation of drug absorption and excretion using cultured cells.

外源性药物在体内的吸收、分布、代谢、排泄等特性是评价药物临床前有效性和安全性的重要环节。为了节省实验动物的使用，我们开发了肠/肾膜囊泡和培养上皮细胞的体外实验系统。本研究通过分析药物在肾细胞（LLC-PK_1、OK、MDCK）和肠细胞（Caco-2）中的跨膜转运，探讨药物吸收和排泄的限速步骤。我们研究了顶侧至基底侧和基底侧至顶侧的药物转运与细胞蓄积的关系。该实验系统可用于评价药物在肠/肾上皮细胞中的转运。2.药物在培养细胞中的毒性：通过测定顶膜和溶酶体的酶活性来评价药物在肾细胞中的毒性。3.药物在细胞单层中转运的动力学分析：建立了一个简单的模型，用于估算药物从顶面介质到细胞、细胞到顶面介质、细胞到基底面介质、基底面介质到细胞的清除率。药物在细胞单层中转运的动力学分析提供了有关药物转运的限速步骤和肠、肾上皮药物转运蛋白活性的有用信息。

The characterization of absorption, distribution, metabolism, excretion of xenobiotics is a important process to evaluate the drug efficacy and safety in preclinical stages. We developed the in vitro experimental systems, the intestinal/renal membrane vesicles and the cultured epithelial cells, to save the use of experimental animals. In this study, we tried to analyze the drug transport across monolayrs of renal (LLC-PK_1, OK,MDCK) and intestinal (Caco-2) cells, and to evaluate the rate limiting step in drug absorption and excretion, as follows :1.Experimental system using cultured cell monolayrs : The intestinal and renal epithelial cells were grown on the microporous membrane filters. We examined the apical-to-basolateral and basolateral-to apical transport of drugs in relation to the cellular accumulation. This experimental system was shown to be useful for evaluate the drug transport in intestinal/renal epithelial cells.2.Toxicity of drugs in cultured cell : The toxicity of drug in renal cells was evaluated by measuring enzyme activities of apical membrane and lysosome. We established the optimal conditions to estimate the nephrotixicity of drugs.3.Kinetic analysis of drug transport in cell monolayrs : We developed a simple model to estimate the clearance from apical medium to cells, cells to apical medium, cells to basolateral medium, and basolateral medium to cells. The kinetic analysis of drug transport in cell monolayrs gave the useful information about the rate limiting step of drug transport and the activity of drug transporter in intestinal and renal epithelium.