Implementation of the caco-2 cell culture model as a predictive tool for the oral absorption of drugs. In-house evaluation procedures.

The Caco-2 cell culture model is widely used during drug development and lead optimization as a predictive tool for the oral absorption of drugs. In order to improve the reliability and quality of the results of Caco-2 experiments and to ensure that the system being used is functionally and enzymatically representative for the intestinal mucosa, it is important to perform a validation of the implemented Caco-2 system. In this paper, we summarize evaluation techniques to guarantee the in-house validity of the model. Theophyllin and sodium fluorescein are used as model compounds to evaluate passive transcellular and passive paracellular transport, respectively. Phenylalanine serves as a substrate to demonstrate active carrier mechanisms. Aminopeptidase and dipeptidyl peptidase are two brush border enzymes present in an active form in the Caco-2 culture model. The presence of an active efflux carrier mechanism is demonstrated with cyclosporin A as a substrate.