Dextran hydrogels for colon-specific drug delivery .2. Synthesis and characterization

Novel hydrogels for colon-specific drug delivery have been designed based on cross-linked dextran. Dextrans with molecular weights from 40,000 to 2,000,000 were cross-linked with two diisocyanates of different lengths. The hydrogels were characterized by the equilibrium degree of swelling and the modulus of elasticity in compression. By application of the theory of rubber elasticity, the cross-linking efficiency was estimated to be max. 10%. It was possible to control the equilibrium degree of swelling and the mechanical strength by changing the structure of the hydrogels. These hydrogels have recently been shown to be degraded by microbial enzymes in the colon and appear to be suitable as drug delivery systems for colon-specific drug delivery.