Among the oldest and best-established methods of permeability measurement are the cell-based colon carcinoma cell line permeability assay (CACO-2) and Madin-Darby Canine Kidney cells (MDCK) . Permeability measurements are realized in transwell plates. Each well is divided into a donor and an acceptor compartment, separated by a membrane. In the case of CACO-2 and MDCK, the membrane consists of a cell monolayer cultured on a solid support. Despite their different origins, the CACO-2 and MDCK are composed of morphologically analogous cells and are widely used as model intestinal membranes .