Preparation and evaluation of diclofinac sodium spray-dried with aqueous-based polymeric systems

Abstract

Diclofenac sodium controlled release microcapsules containing various types and amounts of cellulose derivatives (hydroxypropylmethylcellulose, ethylcellulose) and chitosan were prepared by using spray drying technique. The type and amounts of polymers affected the optimum condition of spray drying process and physicochemical properties of spray dried powder. At the same polymer to drug ratio and spray drying condition, the preparation with hydroxypropylmethylcellulose completely formed spherical microcapsules with smooth surfaces, while drug crystals were presented on the surface of the spray dried microcapsules prepared from ethylcellulose. The powders prepared with chitosan generally were irregular microparticles. All spray dried products had poor flow characteristics. There was no interaction between the drug and polymer. However, some drug crystals transformed to amorphous form due to rapid solidification during spray drying. In addition, it was found that the type of polymer and the polymer to drug ratio were the main factors affecting the crystallinity of diclofenac sodium in spray dried products. The release characteristics of diclofenac sodium from microcapsules decreased with an increase in the amount of polymers. Type of polymer appeared to exert prominent effect on the release rate while the amount of these polymer played less prominent. Microcapsules with hydroxypropylmethylcellulose exhibited higher amount of drug release than those with ethylcellulose. The microcapsules containing 6.57% hydroxypropylmethylcellulose and 13.14% ethylcellulose exhitited a constant release rate up to 24 hours. The release models of all prepared microcapsules were also assessed in comparison with a commercial product.