Micronized Drug Adhesion and Detachment from Surfaces: Effect of Loading Conditions

Drug loading and processing conditions in a dry powder inhaler system are critical for performance of the system since it is these forces that must be overcome to properly redisperse respirable particles. In this work, we have investigated the effects of different loading forces for adhering micronized drug onto surfaces on the drug adhesion, detachment, and aerosol performance under controlled conditions. Drug loading onto a standardized surface was performed under three different loading conditions using turbula-mixer to actively induce powder-surface interactions. It was seen the drug loading increased with increased processing time. The presence of external press-on force also increased drug loading. Drug detachment studies performed using centrifugation method indicated that adhesion forces were the lowest at lower mixing time and increased with increasing press-on forces. Drug aerosolization performance from the surface was assessed using a prototype DPI and confirmed that external forces during drug loading and coating processing played an important role in drug dispersion. It was seen that the respirability of drug particles correlated with mixing times as well as the press-on forces.