Spray-dried HPMC Microparticles of Indomethacin: Impact of Drug-polymer Ratio and Viscosity of the Polymeric Solution on Dissolution

Polymeric microparticles prepared by spray-drying technique were investigated to enhance the dissolution rate of indomethacin (IM) in comparison with conventional microparti cles prepared by co-precipitation solid disper sion method . Drug-polymer ratios and viscosity of polymeric solutions as potential factors were used in order to enhance the dissolution rate of IM. Spraydrying technique was used for preparing of microparti cles using aqueou s suspension of IM in hydroxypropyl methylcellulose (HPMC) polymer solution . The effect of drug-pol ymer ratios on dissolut ion rates of IM was studied in simulating intestinal medium . IM was analyzed spectrophotometrically at λ= 320 nm. For each drug-polymer ratios , low and high viscosity polyme ric solutions were prepar ed and their impacts on the dissolution of IM were bserved. Microparticles were morpholo gically characterized by optical microscopy. The interaction between IM and HPMC was studied by differential scanning calorimetry (DSC) and x-ray diffractometry (XRD). Spherical fluffy microparticles of 1M were obtained using HPMC. It was observed that the prepared spray-dried microparticles significantly increase the dissolution rate of IM. The increase in dissolution rates was achieved with drug:polymer ratios 1:1 as well as 1:2 and interestingly, the decrease in drug content in ratio exceeding 1:2 resulted in reduction in dissolution rates. Also, with all drug-polymer ratios, the low viscosity polymeric solutions gave the higher dissolution rates. In conclusion, HPMC microparticles loaded with IM were prepared by spray-drying technique and the potential of this technique to enhance the dissolution was studied. The findings indicate that the dissolution profile of IM microparticles prepared by spraydrying technique relied on drug-polymer ratios and viscosity of polymeric solutions.