A laser diffraction method has been developed for characterizing adhesive mixtures and estimating their fine particle fraction. The method is robust and highly reproducible. A linear correlation was obtained between the cumulative volume of particles < 5 μm and the fine particle fraction of the API AZD8683 formulations measured by the Next Generation Impactor. The method is very fast, in particular when compared to impactor methods, and has the potential to be an important tool for screening of dry powder formulation during development and for in-process control (IPC).
