An in vitro evaluation of a chitosan-containing multiparticulate system for macromolecule delivery to the colon

A multiparticulate system of chitosan hydrogel beads has been investigated for colon-specific delivery of macromolecules using fluorescein isothiocyanate-labeled bovine serum albumin as a model protein. The hydrogel bead was formed by polyelectrolyte complexation of chitosan with its counterion, tripolyphosphate (TPP). The protein release experiments were carried out in vitro under different conditions to simulate the pH and times likely to be encountered during intestinal transit to the colon. The results show that the hydrogel beads were degraded by rat cecal and colonic enzymes, resulting in a marked acceleration in the release of protein. The ability of rat cecal and colonic enzymes to degrade chitosan hydrogel beads was independent of pretreatment conditions. A commercial beta-glucosidase preparation containing a chitinase did not have a similar effect on the chitosan bead, even though it has been found to mimic the degradation function or rat cecal and colonic enzymes in vitro for chitosan in solution. Degradation of the chitosan-TPP hydrogel beads in the presence of rat cecal and colonic enzymes indicates the potential or this multiparticulate system to serve as a carrier to deliver macro molecules specifically to the colon. (C) 2002 Elsevier Science B.V. All rights reserved.