Optimization and characterization of diclofenac sodium microspheres prepared by a modified coacervation method.

A modified coacervation method for preparing diclofenac sodium loaded chitosan (DFS-C) microspheres, using sodium citrate as cross-linking agent was optimized. A full 2(3) factorial design was used to evaluate the effect of chitosan (CS) concentration, cross-linking agent concentration, and cross-linking time on the properties of the prepared microspheres. The modified coacervation method resulted in higher yield of spherical microspheres even with a lower concentration of CS (0.3%, w/v). The morphology of the microspheres was found to be dependent on the formulation and process parameters. The cross-linking agent concentration had the largest impact on swelling, mucoadhesion, and drug release. Kinetic analysis of the release data revealed a quasi-Fickian diffusion mechanism.