Development of a novel approach towards predicting the milling behaviour of pharmaceutical powders.

A novel approach has been developed for evaluating the milling behaviour of pharmaceutical powders based on their material and mechanical properties obtained by single particle impact testing. Milling behaviour of two widely used pharmaceutical excipients, namely microcrystalline cellulose and alpha-lactose monohydrate has been analysed in an oscillatory single ball mill. It is found that the milling behaviour of these two powders can be described by analogy with a first-order rate process except for alphaLM at 18Hz of milling frequency. At the same time, single particle impact testing has been used to infer the material properties that are related to breakage. The milling rate of these powders is found to correlate well with the parameter representing the material properties including the particle size, density, hardness and critical stress intensity factor. This provides the basis for a novel approach towards analyzing the milling behaviour of a material based on a simple and reliable approach.