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Updated: Jul 10, 2026

Dry Powder and Nebulized Aerosol Inhalation of Pharmaceuticals Delivered to Mice Using a Nose-only Exposure System
Published on: April 6, 2017
Comparison of delivery characteristics from a combination metered-dose inhaler using the Andersen cascade impactor
Changning Guo1, Stacey R Gillespie, John Kauffman
1U.S. Food and Drug Administration, Division of Pharmaceutical Analysis, 1114 Market Street, Room 1002, St. Louis, Missouri 63101, USA. changning.guo@fda.hhs.gov
Abstract:
The purpose of this research was to compare two cascade impaction devices for the aerodynamic particle size assessment of a combination metered-dose inhaler (MDI) product, Combivent. Particle size analysis was performed using an Anderson Mark II cascade impactor (ACI) and a Next Generation Pharmaceutical Impactor (NGI), both fitted with a preseparator and either a 1 L glass chamber or USP throat, and operated at various flow rates. Particle size distributions (PSDs) and dose delivery profiles were assessed by means of the mass median aerodynamic diameter (MMAD), geometric standard deviation (GSD), fine particle fraction <5 micron aerodynamic diameter (FPF(<5 microm)), and induction port deposition fraction (IPF). Under their normal operating conditions, the ACI (28.3 L/min) and the NGI (30 L/min) yield similar PSDs and dose delivery profiles. However, this equivalent performance for the ACI and the NGI no longer exists at a higher flow rate of 60 L/min. Furthermore, changes in PSD results may also be obtained between different operators and/or when different induction port designs were employed. Thus, it is strongly recommended that special care be taken to eliminate variation in experimental parameters and/or selection of ancillary devices such as the preseparator, induction port or throat, to insure good repeatability and reproducibility when testing inhalation drugs.
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