The aim of the current work was to investigate the assumption that: dynamics of inspiration affects the aerosol characteristics emitted from the passive dry powder inhaler and, subsequently, influences the total quantity of drug penetrating lower respiratory tract. Real-time aerosol behavior of the spray-dried powder was studied experimentally utilizing New Generation Cyclohaler for two breathing curves, at the outlet of the inhaler. Aerosol characterization was done by laser diffraction, reliably capturing the aspects of time dependency. It resulted in time evolution of volumetric particle size distribution and was extended with the analysis of local particle dynamics over the studied cross-section. Results presented in the paper confirm its assumption to be true. Different inhalation curves were associated with substantially different inhaler performances. The quicker and more forceful curve II produced better dispersion. Aerosol dynamics is particularly susceptible to the strong aerodynamic effects of unsteadiness acquired from relatively small values of flow rates. The initial part of inspiration may contribute to achieving higher respirable dose content before the peak inspiratory flow is attained. Deaggregation upon impactions with chamber wall and subsequent collisions with grid are assumed to produce desired fine particle fraction. The paper elucidates the relevance of considering time-varying character of inspiration. (C) 2016 Elsevier Ltd. All rights reserved.