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

外源性药物的吸收、分布、代谢、排泄特性是临床前评价药物有效性和安全性的重要环节。我们开发了体外实验系统，即肠/肾膜囊泡和培养的上皮细胞，以节省实验动物的使用。在本研究中，我们试图分析药物在肾(LLC-PK_1，OK，MDCK)和肠(Caco-2)细胞单层之间的转运，并评价药物吸收和排泄的限速步骤，具体如下：1.细胞单层培养实验系统：将肠和肾上皮细胞生长在微孔滤膜上。我们研究了药物从根尖到基底侧和从基底到根尖的转运与细胞堆积的关系。2.药物在培养细胞内的毒性：通过测定细胞顶膜和溶酶体的酶活性来评价药物对肾细胞的毒性。建立了评价药物肾毒性的最佳条件。3.细胞单层药物转运动力学分析：我们建立了一个简单的模型来估算药物从根尖介质到细胞、细胞到根尖介质、细胞到基侧介质和基侧介质到细胞的清除量。药物在细胞单层转运的动力学分析为药物转运的限速步骤和肠、肾上皮细胞药物转运活性提供了有用的信息。

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.