In the development of new active substances, predicting their absorption in human body is crucial and can be achieved by performing permeability assays. Cell models based on different cell types have become commonly used tools for permeability determination of active substances due to many advantages and are also recognized by international guidelines. Cell line Calu-3, which was derived from human lung adenocarcinoma, has been used as one of the options for cell model’s preparation because of its ability to form monolayers with tight junctions, different membrane transporter expression, fast growth and source of extensive cell proliferation which can be used for permeability assays. Our aim in this work was to evaluate the ability of two prepared cell models (model liquid-liquid and model air-liquid) for permeability classification of the active substances according to their properties. Tests for mycoplasma contamination were performed during the cell culturing. Integrity of the cell layers was evaluated by transepithelial electrical resistance (TEER) measurements and paracellular permeability determination of zero permeability marker Lucifer yellow (LY). Model substances with low, moderate and high permeability according to ICH M9 guidelines were used in permeability assays. Results indicate suitability of both prepared cell models for classification of active substances to high and low permeability classes based on BCS (Biopharmaceutical Classification System) classification. By performing permeability assays both in apical-to-basolateral and basolateral-to-apical directions we determined which tested substances are involved in efflux mechanism. Those substances are nadolol (P-glycoprotein substrate) on both cell models, furosemide (P-glycoprotein and BCRP substrate) on cell model liquid-liquid, hydrochlorothiazide (BCRP substrate) on both models and chlorothiazide (BCRP substrate) on cell model liquid-liquid. By performing permeability assays with P-glycoprotein inhibitors (PSC 833 and verapamil) we confirmed the expression of that protein in Calu-3 cells. Efflux ratio (ER) for rhodamine 123 decreased significantly on both cell models after using both P-glycoprotein inhibitors.
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