Spray-dried HPMC Microparticles of Indomethacin: impact of drug-polymer ratio and viscosity of the polymeric solution on dissolution

ABSTRACT

Polymeric microparticles prepared by spray-drying technique were investigated to enhance the dissolution rate of indomethacin [IM] in comparison with conventional microparticles prepared by co-precipitation solid dispersion method. Drug-polymer ratios and viscosity of polymeric solutions as potential factors were used in order to enhance the dissolution rate of IM. Spray-drying technique was used for preparing of microparticles using aqueous suspension of IM in hydroxypropyl methylcellulose [HPMC] polymer solution. The effect of drug-polymer ratios on dissolution rates of IM was studied in simulating intestinal medium. IM was analyzed spectrophotometrically at lambda=320 nm. For each drug-polymer ratios, low and high viscosity polymeric solutions were prepared and their impacts on the dissolution of IM were observed. Microparticles were morphologically 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 IM 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 11 as well as 12 and interestingly, the decrease in drug content in ratio exceeding 12 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 spray-drying technique relied on drug-polymer ratios and viscosity of polymeric solutions