Influence of extended dwell time during pre- and main compression on the properties of ibuprofen tablets.

The low melting point, poor flow, physico-mechanical properties (particle size distribution, shape, particle surface roughness) and deformation mechanism of ibuprofen in combination with its high dose in tablets all contribute to the problems observed during the compaction of ibuprofen-based formulations. Since ibuprofen is plastically and elastically deforming, the rate of compaction plays an important role in both the final tablet properties and the risk of capping, laminating and sticking to the punches. While the compaction rate in most tableting machines is only determined by the tableting speed, the high speed rotary tableting machine used in this research project (MODUL™ P, GEA Process Engineering, Halle, Belgium) can adjust and control the dwell time independently from the tableting speed, using an air compensator which allows displacement of the upper (pre-) compression roller. The effect of this machine design on process parameters and tablet properties was investigated. Granules containing 80% ibuprofen were compressed into tablets at 250, 500 and 1000 tablets per minute via double compression (pre- and main compression) with or without extended dwell time. Prior to tableting, granule properties were determined. Process parameters and tablet properties were analyzed using Multivariate Data Analysis. Principal Component Analysis provided an overview of the main phenomena determining the tableting process and Partial Least Squares Analysis unveiled the main variables contributing to the observed differences in the tablet properties.