The pharmaceutical industry still produces the vast majority of their products, from powdered ingredients,
in the form of solid doses.
Despite their ubiquity, powders are difficult materials to characterise and understand, as evidenced by the frequent
problems encountered during manufacture. The reason for this is their complex rheological behaviour coupled with
numerous environmental variations, such as humidity. Equally, the range of processes used to manipulate powders
subject them to extremes of stress from high compaction loads seen in compactors to the dispersed state seen in fluidised
Thus, it is evident that ensuring that the powders characteristics are compatible with the way they are to be processed
is a clear prerequisite for today’s Quality by Design driven manufacturing.
Modern, computer controlled instrumental techniques, including the dynamic, bulk and shear property measurements have enabled direct
measurements of a powders response to aeration, consolidation and flow rate - all at low stresses - as well as quantifying shear and bulk
properties (such as density, compressibility and permeability).
In order to demonstrate how fully characterising a powder can be used in the design, operation and troubleshooting of processes, this paper
will present examples of common pharmaceutical unit operations and the different powder characteristics that most influence the performance