Compressibility analysis as robust in-die compression analysis for describing tableting behaviour

Abstract Objectives Compressibility of materials is determining the tableting behaviour and tablet properties during and after manufacturing. The compressibility constant has not been investigated as an in-die method yet and was therefore compared with the Heckel analysis for describing the compressibility of materials during tableting in the present study. Methods Various parameters influencing tableting, such as compression pressure, compression speed and punch diameter, were used to analyse the robustness of both methods and to evaluate the informative value of the compression parameters. Twelve common pharmaceutical excipients were used to cover a wide range of material properties. Key findings The compressibility constant was successfully applied as an in-die method and proved to be more robust against the influencing parameters during tableting than the Heckel analysis. A good correlation between the out-of-die and in-die method was found for both methods but could not be observed between the compressibility constant and the yield pressure from Heckel analysis. The methods are both describing the volume reduction of materials under pressure but focus on different material properties. Conclusions For material characterisation in the field of tableting, the compressibility constant can be additionally applied in the future to be able to determine another compressibility parameter in combination with the yield pressure.