Development of controlled release diclofenac sodium by spray daying with acrylate aqueous disperson

Abstract

Diclofenac sodium microspheres were prepared by spray drying technique. Acrylate aqueous dispersions (Eudragit® NE 30D, Eudragit® RL 30D and Eudragit® RS 30D) were used to control the release of drug from microspheres. Colloidal silica (Aerosil®) of 30% w/w of polymer was added as an antiadherent agent. The influence of processing variables, inlet air temperature of 150 to 210๐C and the amount of polymer varied from 5 to 20% on the physicochemical properties of spray dried powders were studied. The release characteristics of drug from the obtained microspheres were performed in both pH-change and phosphate buffer pH 6.8 systems. The scanning electron photomicrographs showed that the size of spray dried powders was affected by both the inlet temperature and the amount of polymer but the shape was only by the former. The powders tended to be larger and more spherical when increasing the inlet temperature. At lower inlet temperatures, the size seemed to be larger when decreasing the amount of polymer. The results were reversed at higher inlet temperature. These were corresponding to their specific surface area and total pore volume. The X-ray diffractograms and DSC thermograms of the obtained microspheres showed lower intensity with higher baseline and lower endothermic and exothermic peaks, respectively, indicating of an increment of amorphous form when increasing the inlet temperature. The IR spectra revealed no interaction between drug and polymer. The release of drug from microspheres was strongly medium dependent. It was much faster in phosphate buffer pH 6.8 than in pH-change system. Increasing the amount of polymer or decreasing the inlet temperature decreased the release of drug. The release profile of drug from Eudragit® NE 30D microspheres was more linear than from other grades of the polymer. Moreover, the drug could be sustained release throughout 24 hours in the pH-change medium, comparable to commercial products.