In vitro Evaluation of Genipin-Crosslinked Na-Alginate/Chitosan Hydrogel Films for Delivery of Metformin: Effect of Chitosan Molecular Weight

Objectives: In this study, central composite factorial design was used for the preparation and optimization of chitosan/Na-alginate hydrogel films containing metformin via solvent evaporation technique. Methods: Low and high molecular weight (MW) chitosan was used as a polymer in different concentrations while genipin was used as a crosslinking agent. Drug release studies were performed in simulated gastric and intestinal fluids at pH 1.2 and 7.4 of formulated hydrogels. Results: For low MW chitosan hydrogel, the highest drug release at pH 1.2 was observed i.e., 9.82% for 2 hrs while at pH 7.4, 95.52% drug release was observed after 12 hrs. In case of high MW chitosan hydrogel 9.67% drug release at ph1.2 for 2 hrs and 90.63% drug release at pH 7.4 after 12 hrs was observed. The highest T50% of low MW and high MW chitosan hydrogel was observed as 22.72 and 33.34 hrs, respectively, while the highest dynamic swelling was observed as 8.21 and 7.9, respectively. Conclusion: It was found that by changing the ratios of polymers as well as crosslinking agent, the release rate of metformin can be modified. Low MW chitosan hydrogel showed an increased release rate than high MW chitosan hydrogel and by increasing the concentration of crosslinking agent, the release rate was found to be decreased and vice versa.