Prediction of suitable amount of water addition for wet granulation.

The purpose of this study was to predict the amounts of water addition suitable for pharmaceutical formulations in wet granulation, using a high-speed mixer or a fluidized bed granulator, before granulation trials. In order to determine the suitable amount of water addition, each excipient was first subjected to kneading with water in a mortar and a refractive near-infrared moisture sensor (IR sensor) measured the amount of water at the powder surface. Further by analysis the plot (output value of the IR sensor vs. amount of added water) for each excipient, the amount of water addition for granulation was determined for it. As a second step, two model formulations were designed and suitable amounts of water for granulation were predicted by summation of the obtained excipient values. The predicted value was compared with the experimental value for high-speed mixer granulation. The predicted and experimental amounts of water addition corresponded for the two model formulations, suggesting that the above method is useful for estimating suitable amounts of addition of water for formulations before granulation trials.