(637h) Effect of Surface Modification On Flow and Packing Properties of Fine Powder Under Humid Environment

Moisture content of any of the formulation component can pose a considerable threat to the performance and quality of pharmaceutical product. Thus protection of pharmaceutical powders from humid or moist conditions has always been an area of prime importance in pharmaceutical industry. In the present study, surface modification through dry coating has been successfully exploited for the improvement of flow and packing properties of ~18 micron corn starch powders under different humid conditions (relative humidity 30% to 90%). Both uncoated and surface modified powders were characterized for flow and packing properties using tap density apparatus and FT4 powder rheometer. While flow and packing properties of uncoated starch powder deteriorated with increasing the relative humidity (RH), surface modified starch powder showed improvement in packing and flow properties as indicated by shear test, compressibility test and bulk density determination. It was found that moisture content of both uncoated and coated starch samples increases uniformly as a function of relative humidity. However, surface modified starch powder showed consistently improved property throughout the experimental range of humidity. The study demonstrates that surface modification can be useful to avoid detrimental effects of dominant interparticle forces like capillary forces at changing humidity conditions.