Preparation of spray-dried microspheres of indomethacin and examination ofthe effects of coating on dissolution rates

In this study, microspheres were prepared by the spray drying technique usi ng suspensions of indomethacin (IM) as active substance and coated by three different polymers in order to increase the dissolution rate of IM. Water solutions (0.1, 0.2 and 0.5%) of hydroxypropylmethyl cellulose (HPMC), poly vinyl alcohol (PVA) and hydroxypropyl cellulose (HPC) were used as coating materials. Polyethylene glycol 400 (PEG 400) was added to all formulations as plasticizer. Changes of particles size and surface characteristics of th e coated products were examined using optical microscopy and scanning elect ron microscopy (SEM), respectively. The effects of coatings on the dissolut ion rates of IM were examined using USP XXIII Method II in water and phosph ate buffer pH 7.4. It was observed that coating the IM particles with HPMC, PVA and HPC polymers using the Spray-Drying Technique increased the dissol ution rate of IM significantly.