Prediction of granule physical property by a novel compression energy of wet powder

Wet granulation is a very important process and a reliable evaluation method for formulation study; thus it requires appropriate process control. In this study, a novel and effective method that involves a compression test of wet powder is proposed. Here, the compression energy, which could predict the capability of the wet powder for extrusion granulation as well as the physical properties of the final products, is used as a novel characteristic of wet powder. The compression energy was defined as the energy consumption derived from the compression speed and the transmission loss during the compression test. Lactose monohydrate was mixed with various additives such as hydroxypropylcellulose in the mass ratio of 0-10%. Various amounts of water were fed into the mixtures, which were kneaded in a planetary motion mixer to prepare the kneaded wet powders. The characteristics of these powders were evaluated by the compression energy. The kneaded wet powders were then extruded through an extrusion granulator, the electrical loads of the granulator during the operation were analyzed as the extrusion energy, and the physical properties of extruded granules were investigated. As a result, the granule strength and granule size distribution showed a good correlation with the compression energy. A good correlation was also observed between the compression energy of the kneaded wet powder and the extrusion energy regardless of the different additives and water contents. It was concluded that the compression energy of the wet powder could be used for the formulation study and the process control of wet granulation.