The effect of carrier surface roughness on wall collision‐induced detachment of micronized pharmaceutical particles

Repeated particle‐wall collisions are regarded as a contributory mechanism to the detachment of micronized pharmaceutical particles from carrier particles in inhaler devices. A natural and not much studied feature of these carrier particles are their surface roughness. In the present study, we simulate the collision‐induced dispersion behavior of dry‐coated rough particles by means of the discrete element method. Carrier particles with controllable length scales of roughness are generated based on the concept of Fourier shape descriptors. The dispersion efficiency correlates well with the statistical measures of the surface asperities. Moreover, the collision energy is found to contribute to the degree of fine particle detachment. At the rebound, it is observed that the majority of remaining fine particles fall into the particle cavities and establish multiple contacts with the carrier surface. These results corroborate with experimental findings and emphasize the significant effect of surface asperities in the context of inhalable particles.