A counter-swirl design concept for dry powder inhalers

Vishal Chaugule; Larissa Gomes Dos Reis; David F Fletcher; Paul M Young; Daniela Traini; Julio Soria

doi:10.1016/j.ijpharm.2023.123694

A counter-swirl design concept for dry powder inhalers

Int J Pharm. 2024 Jan 25:650:123694. doi: 10.1016/j.ijpharm.2023.123694. Epub 2023 Dec 9.

Authors

Vishal Chaugule¹, Larissa Gomes Dos Reis², David F Fletcher³, Paul M Young⁴, Daniela Traini⁵, Julio Soria⁶

Affiliations

¹ Laboratory for Turbulence Research in Aerospace and Combustion (LTRAC), Department of Mechanical and Aerospace Engineering, Monash University, Clayton Campus, Melbourne, Australia.
² Respiratory Technology, Woolcock Institute of Medical Research, Sydney, Australia.
³ School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, Australia.
⁴ Respiratory Technology, Woolcock Institute of Medical Research, Sydney, Australia; Department of Marketing, Macquarie Business School, Macquarie University, Australia.
⁵ Respiratory Technology, Woolcock Institute of Medical Research, Sydney, Australia; Macquarie Medical School, Department of Biological Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Australia.
⁶ Laboratory for Turbulence Research in Aerospace and Combustion (LTRAC), Department of Mechanical and Aerospace Engineering, Monash University, Clayton Campus, Melbourne, Australia. Electronic address: julio.soria@monash.edu.

PMID: 38081562
DOI: 10.1016/j.ijpharm.2023.123694

Abstract

A swirling airflow is incorporated in several dry powder inhalers (DPIs) for effective powder de-agglomeration. This commonly requires the use of a flow-straightening grid in the DPI to reduce drug deposition loss caused by large lateral spreading of the emerging aerosol. Here, we propose a novel grid-free DPI design concept that improves the aerosol flow characteristics and reduces the aforementioned drug loss. The basis of this design is the implementation of a secondary airflow that swirls in the opposite direction (counter-swirl) to that of a primary swirling airflow. In-vitro deposition, computational fluid dynamics simulations and particle image velocimetry measurements are used to evaluate the counter-swirl DPI aerosol performance and flow characteristics. In comparison with a baseline-DPI that has only a primary swirling airflow, the counter-swirl DPI has 20% less deposition of the emitted drug dose in the induction port and pre-separator of a next generation impactor (NGI). This occurs as a result of the lower flow-swirl generated from the counter-swirl DPI which eliminates the axial reverse flow outside of the mouthpiece and substantially reduces lateral spreading in the exiting aerosol. Modifications to the counter-swirl DPI design were made to prevent drug loss from the secondary airflow tangential inlets, which involved the addition of wall perforations in the tangential inlets and the separation of the primary and secondary swirling airflows by an annular channel. These modified DPI devices were successful in that aspect but had higher flow-swirl than that in the counter-swirl DPI and thus had higher drug mass retained in the device and deposited in the induction port and pre-separator of the NGI. The fine particle fraction in the aerosols generated from all the counter-swirl-based DPIs and the baseline-DPI are found to be statistically similar to each other.

Keywords: Computational fluid dynamics; Dry powder inhaler; Particle image velocimetry; Particle tracking; Swirling flow; in-vitro deposition.

MeSH terms

Administration, Inhalation
Aerosols
Dry Powder Inhalers* / methods
Equipment Design
Lung*
Particle Size
Powders

Substances

Aerosols
Powders