Formulation Development and Characterization of Guar Gum Microspheres for Colon Delivery

In the present work, colon specific drug delivery systems have been selected, to deliver the drug locally to colon for longer period of time. Cross-linked guar gum microspheres of model drug secnidazole were prepared by emulsification method and were evaluated for size and surface morphology by SEM, encapsulation efficiency, yield, swelling study. In vitro drug-release studies were performed in conditions simulating stomach-to-colon transit in the presence and absence of rat cecal contents. The marketed product was also compared for drug release profiles. The guar gum microspheres retard the release of drug in stomach but it facilitates the release of large amount of drug in the colon in the presence of rat cecal contents, as these have polysaccharides enzymes that degrade the guar gum in the colon. The release data shows that 44.4% of drug was released in the presence of rat cecal content release medium in 24 hours. Drug release data were fitted to different mathematical model to find release kinetic of drug. The stability studies were performed by storing the microspheres at different conditions of storage. The significance of differences was evaluated by analysis of variance (ANOVA). Differences were considered statistically significant at P < 0.05.