Optimizing the inclination angle of the swirl chamber in dry powder inhalers for improved carrier particle retention

ABSTRACT

This study investigated the effect of the inclination angle of the swirl chamber in a dry powder inhaler (DPI) on the retention of carrier particles. It was found that a small inclination angle can retain most carrier particles within the chamber by promoting constant collisions with the wall. However, care must be taken to avoid a large inclination angle, which can result in a stronger siphoning effect at the top of the swirl chamber. Two DPIs, Cyclohaler^® and an in-house DPI, were studied using Euler/Lagrangian simulations to determine the optimal inclination angle for two inhalation pressure drops (2 and 4 kPa) and two carrier sizes (46 and 83 µm). The preferred outcome is for most carriers to remain in the swirl chamber while most drugs leave the inhaler. For an inclination angle of 5° and a carrier size of 46 µm, more than 50% of drugs escaped while less than 3% of carriers escaped. Experimental studies using a next generation impactor (NGI) confirmed the simulation results. This novel finding provides guidance for preventing carrier lactose particles from leaving DPIs.

Copyright © 2024 American Association for Aerosol Research

Graphical Abstract

Editor:

• Darragh Murnane

Acknowledgment

The authors would like to acknowledge the financial support received from the National Key Research and Development Program of China (project 2022YFC2805704) and the Chinese Fundamental Research Funds for Central Universities (project 2020kfyXJJS065). Patents have been filed for the technology described in this work, which may result in financial benefits for the authors.

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Funding

The authors would like to acknowledge the financial support received from the National Key Research and Development Program of China (project 2022YFC2805704) and the Chinese Fundamental Research Funds for Central Universities (project 2020kfyXJJS065).