Granulation Rheology I: Equipment Design and Preliminary Testing

Abstract
One of the most common pharmaceutical dosage forms is the compressed tablet, and of the several methods of preparing tablets, wet granulation remains widely used throughout the pharmaceutical industry. An apparatus was designed to follow the physical changes occurring in the granulation process. Its operation and preliminary results are presented. As dry solid is wetted with granulating liquid, it passes through several stages, as it becomes wetter, it should exhibit a resistance to flow analagous to a viscous liquid. This resistance (force) can be measured. The test procedure follows the material from a dry powder through its maximum resistance and finally to a slurry. Such profiles could represent a characterization method for the solid and/or the liquid. Materials tested included six common tablet excipients; these have been limited to single component granulations. Results indicate this apparatus is reproducible for these simple systems. Materials are shown to behave differently in the granulation process, and the apparatus appears capable of distinguishing between different materials.