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

In this study, microspheres were prepared by the spray drying technique using 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), polyvinyl 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 the coated products were examined using optical microscopy and scanning electron microscopy (SEM), respectively. The effects of coatings on the dissolution rates of IM were examined using USP XXIII Method II in water and phosphate 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 dissolution rate of IM significantly.