Agglomerate strength and dispersion of pharmaceutical powders

This study aims to investigate quantitatively the direct correlation between the mechanical strength of powder agglomerates and their dispersion into aerosols by a dry powder inhaler. Agglomerates of mannitol as a model drug-only formulation were prepared by a rolling method followed by exposure to various relative humidity (RH: 55 , 82 , 86 and 90 ). The agglomerate strength was obtained from the compression of single agglomerates at a selected speed rate using an Instron testing machine. The dispersion performance (FPFLoaded) was determined at flow rates of 60 and 100lmin-1 using an Aeroliser? coupled to a multistage liquid impinger. Results showed an inverse linear relationship between the agglomerate strength and the dispersion performance. An increase in strength from 3 to 183kPa resulted in a significant drop (P