DEM analysis of powder deaggregation and discharge from the capsule of a carrier-based Dry Powder Inhaler

In carrier-based Dry Powder Inhalers (DPI), fine API powder covers the surface of bigger carrier particles giving rise to dry coated particles, such that their flow properties are improved. In the hard-shell capsule of Cyclohaler DPI, powder deaggregation and discharge occurs as a result of the centrifugal motion and the subsequent aerodispersion to the mouthpiece induced by the patient's inhalation. In this work, the crucial initial transient of this dispersion process was analysed through DEM (Discrete Element Method) simulations, by considering the solid phase only. The accelerated rotational motion of the cap-sule was simulated in the frame of reference of an observer rotating with the capsule, appropriately con-sidering fictitious forces. The effect of the vibrations due to collisions between the capsule and the inhaler on powder discharge was evaluated as well for carrier particle systems. The results provide a punctual mapping of the particle-wall collisions within the capsule, allowing the path of the solids to be tracked until discharge. Simulations were carried out on drug-carrier blends with extreme size difference, consid-ering adhesive interactions, elucidating the early-stage dynamics of the detachment process that occurs inside the capsule due to the interactions between particles and between particles and walls.(c) 2022 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.