Evaluation of Microwave Drying for Pharmaceutical Granulations

Abstract

The experiments were designed to compare the granule characteristics following the microwave drying and conventional tray drying. The formulations were designed to study the effect of microwave radiation under different conditions. This later criterion was studied by using granules prepared with different granulating fluids. The granules were prepared by using sulfathiazole as a model drug, lactose as a diluent, and starch as a disintegrating agent. The granulating fluids were 5% solution of PVP in 100% water, 50% water 50% ethanol, and 100% ethanol, respectively. The granules were dried in a microwave oven and in a conventional tray oven at 40±2° C. The loose and bulk densities were measured in a 100 ml glass cylinder. The granule morphology was examined using a scanning electron microscope. Dissolution rates of the granules were monitored using a rotating paddle dissolution apparatus. The loose and tapped bulk densities, the percentage compressibility, hardness, and the time required for 100% dissolution of the granules dried in the microwave oven and in the conventional tray oven were not significantly different (p>0.05). The scanning electron micrographs of the granules also showed no evidence of morphological changes or thermal damage to the granule surface or interior. In conclusion, the microwave radiation has no significant effect on the granules' characteristics.