Design and development of hydrogel beads for targeted drug delivery to the colon.

The purpose of this research was to develop and evaluate a multiparticulate system of chitosan hydrogel beads exploiting pH-sensitive property and specific biodegradability for colon-targeted delivery of satranidazole. Chitosan hydrogel beads were prepared by the cross-linking method followed by enteric coating with Eudragit S100. All formulations were evaluated for particle size, encapsulation efficiency, swellability, and in vitro drug release. The size of the beads was found to range from 1.04 +/- 0.82 mm to 1.95 +/- 0.05 mm. The amount of the drug released after 24 hours from the formulation was found to be 97.67% +/- 1.25% in the presence of extracellular enzymes as compared with 64.71% +/- 1.91% and 96.52% +/- 1.81% release of drug after 3 and 6 days of enzyme induction, respectively, in the presence of 4% cecal content. Degradation of the chitosan hydrogel beads in the presence of extracellular enzymes as compared with rat cecal and colonic enzymes indicates the potential of this multiparticulate system to serve as a carrier to deliver macromolecules specifically to the colon and can be offered as a substitute in vitro system for performing degradation studies. Studies demonstrated that orally administered chitosan hydrogel beads can be used effectively for the delivery of drug to the colon.