RESUMO
Objective: To develop and evaluate the mucoadhesive microsphere using combinations of natural polymers chitosan and xanthan gum for sustained release. Methods: In the present work mucoadhesive microspheres were prepared by using natural polymers like chitosan and xanthan gum by using the emulsion chemical cross-linking method. Chemical cross-linking was done by using glutaraldehyde. The 22 factorial design was employed to show the effect of cross-linking agent and processing factor-like stirring and speed. Prepared microspheres were evaluated for their particle size, surface morphology, drug entrapment efficiency, in vitro drug release, swelling index, and mucoadhesive strength. Results: The size of microspheres of factorial batches were in the range of 26-46 µm. The swelling index was showed in the range of 1.51-1.66 percentage. The equation of multiple regression revealed that there was significant interaction among factors. The glutaraldehyde concentration had a positive effect on % entrapment efficiency, % cumulative drug release and % mucoadhesion. Stirring speed showed a negative impact on % entrapment efficiency, % cumulative drug release and % mucoadhesion. The interactive effect of glutaraldehyde concentration and the stirring speed was found to be positive for % entrapment efficiency and % cumulative drug release. In vitro drug release study of optimized formulation F2 show 96 % of drug release with 6 h indicating sustained release behavior with diffusion mechanism. The SEM image of the optimized batch was spherical with a porous surface. Conclusion: The results obtained in this research work indicated that a promising potential of chitosan and xanthan gum combination for the preparation of the mucoadhesive microsphere of Racecadotril.