Visualisation of Pharmaceutical Material Surface Stability as a Function of Mechanical Processing

In most pharmaceutical dry powder formulations, crystalline drugs or excipients must exhibit a specific functionality that requires a high-energy processing such as milling or micronisation which could induce regions of amorphous state in the material (1). In general, amorphous materials are thermodynamically unstable and may re-crystallise, if the molecular mobility within the region is high enough to allow such re-ordering (2). The differences in physical properties between crystalline and amorphous material can be of importance when affecting the mixing and aerosolisation properties of the active ma terial (3)