Author(s): Lentz KA, Hayashi J, Lucisano LJ, Polli JE
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Abstract The objectives were: (1) to develop a more rapid, reduced serum culture system for Caco-2 monolayers, relative to the traditional 21-day, 10\% fetal bovine serum (FBS) system; and (2) to determine the biopharmaceutical drug classification of an oral therapeutic agent using this new system. Caco-2 cells were grown in the six well format on polycarbonate filters, in medium containing 2\% iron supplemented calf serum (sCS) and a combination of growth factors and hormones. After 4 days in culture, permeabilities of three marker compounds (metoprolol, mannitol, and taurocholate) across monolayers were determined, and compared to permeabilities from the traditional 21-day, 10\% FBS system, using cells at similar passage number. Cell morphology, degree of cell differentiation, and the presence of two efflux pumps were assessed. The 2\% sCS model was also used to classify the permeability of an oral therapeutic agent as high or low. No difference in permeability was observed for metoprolol transport (P = 0.38) between the two culture methods, and the values obtained were independent of passage number of the cells. Mannitol permeability was about 2-fold higher from the 2\% sCS system, as compared to the 10\% FBS system. Taurocholate permeability was low indicating the 2\% sCS culture at 4 days lacked this particular active transporter capability. Electron micrographs of cells grown in the 2\% sCS system at 4 days revealed the presence of microvilli and tight junctions. P-glycoprotein and an efflux pump for furosemide were functionally present. The 2\% sCS system indicated the oral therapeutic agent as highly permeable, which agreed with the 10\% FBS system. This new system provides a rapid, accurate, and economical option for passive permeability determination, and appears to be applicable to the proposed Biopharmaceutics Classification System (BCS).
This article was published in Int J Pharm
and referenced in Journal of Bioequivalence & Bioavailability