Dextran hydrogels for colon-specific drug delivery

Novel hydrogels based on dextran crosslinked with diisocyanate have been proposed for colon-specific drug delivery. The hydrogels have been characterized by equilibrium degree of swelling and mechanical strength. Degradation of the hydrogels has been studied in vitro using dextranase, in vivo in rats and in a human fermentation model. It was found that by changing the chemical composition of the hydrogels it is possible to control the equilibrium degree of swelling, mechanical strength and degradability. The dextran hydrogels were degraded in vivo in the cecum of rats but not in the stomach. Furthermore, the dextran hydrogels were degraded in a human colonic fermentation model, indicating that dextranases are indeed present in human colonic contents. Finally, release of hydrocortisone from the hydrogels was evaluated. It was found to depend on the presence of dextranases in the release medium. The results suggest that the dextran hydrogels are promising as drug carriers for colon-specific drug delivery.

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