New insights into segregation during tabletting.

The aim of this study was to evaluate how different granule size distributions affect the tablet compression process. The emphasis was on developing new analytic methods for compression data for entire batch. In all, 18 batches of granules containing theophylline and lactose were tabletted, using an instrumented eccentric tabletting machine. During tablet compression, upper and lower punch forces were recorded. Mathematical methods were developed for analysing the compression data during tabletting. The results suggested two types of undulation in the tabletting data: (1) short-time scale variation or tablet-to-tablet changes in force data and (2) long-time scale undulation describing the changes occurring throughout the tabletting process, such as segregation. These undulation phenomena were analysed, using various mathematical methods. In addition the results suggest that smaller particles have better tabletting properties, to a certain limit. However particle size alone cannot explain the tabletability of granules.