The size distribution of pharmaceutical aerosols is important in determining the deposition site of the inhaled drug particles in the respiratory tract.Cascade impaction is the industry's preferred method for particle size anal., but measurements can be time-consuming and provide no information regarding the dynamics of the aerosol formation.Laser diffraction can accurately provide this information, allowing different drug formulations to be rapidly screened for delivery efficacy.Here, the two techniques have been combined to show that, in dry powder inhaler formulations, drug particles produced using supercritical-fluid crystallization disperse to a smaller particle size than micronized particles, providing more reproducible drug delivery.