Résumé
The aim of this study was the preparation of diclofenac sodium microcapsules using cellulose acetate as a polymer and polyvinyl acohol as an emulsifying agent by solvent evaporation technique. Preliminary experiments were carried out to determine practically the volume range of both the external phase, the internal organic phase, the concentration range of emulsifier and the drug to polymer ratio. The prepared microcapsules were evaluated for their morphology and surface structure, average particle size, yield, drug loading efficiency, and their release pattern. The results of these trials revealed that diclofenac sodium-cellulose acetate microcapsules were successfully prepared applying the solvent evaporation technique. The characteristics of the produced microcapsules were highly affected by the different formulation parameters. Changing the polymer content didn't affect the morphology of the produced microcapsules. The microcapsules were discrete, spherical and freely flowing. The increase in the polymer amount increased the mean particle size and decreased the yield of the microcapsules due to the increase in the internal phase viscosity. The drug loading efficiency was significantly increased with the increase in methylene chloride-acetone volume. The condensed monolayer of polyvinyl alcohol was not achieved at concentrations below 0.5%. Above this concentration] the increase in polyvinyl alcohol content decreased both the mean particle diameter end the percentage yield of the microcapsules. The release of diclofenac sodium from cellulose acetate microcapsules was pH dependent. The drug was released faster in the alkaline medium compared to acidic medium