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Purpose: The aim of this study is to evaluate and compare the performance, for the administration of fluticasone propionate with a pressurized metered-dose inhaler (pMDI), of two low-tech paperboard spacers versus two commercially available valved holding chambers (VHC)., Methods: According to the Canadian standard CAN/CSA-Z264.1-02, total emitted dose (TED) and aerodynamic size distribution were measured for the pMDI in combination with 4 different spacers: a homemade paper cup spacer, the DispozABLE® paperboard spacer, the AeroChamber Plus® plastic VHC, and the Vortex® aluminium VHC., Results: The two disposable paperboard spacers had a lower TED compared to the aluminium VHC, but delivered more than 2.5 times the dose of fluticasone than the commercial plastic VHC. The 3 antistatic devices (i.e. the aluminium VHC, the paperboard DispozABLE® spacer and the paper cup spacer) delivered a significantly higher dose of fine particles than the less antistatic plastic VHC. Their fine particle fraction was statistically similar to that obtained with pMDI without spacer. This respirable fraction ensures an optimal therapeutic effect. All spacers limited the flow of coarse particles, thus avoiding adverse effects on the trachea and oropharynx., Conclusion: We have shown that inexpensive and low-tech paperboard spacers are interesting alternatives for the administration of aerosols., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Experiments were conducted to illustrate some of the challenges associated with measuring dynamic MDI aerosols. Experimental HFA-134a solution MDIs containing 8 or 20% ethanol were measured using the Andersen cascade impactor using three different inlets. It was demonstrated that the size distribution of MDI aerosols changes substantially during the measurement process. The measured size distribution was shown to be dependent on the degree of evaporation that has occurred prior to size measurement. Additionally, the degree of evaporation prior to measurement also influences the number of modes present in the measured size distribution. While MDI aerosols appeared to have a separate large particle mode when measured using the U.S. Pharmacopeial induction port ("USP inlet"; [U.S. Pharmacopeia, 1996. Physical tests and determinations <601> aerosols, metered dose inhalers, and dry powders. Pharmacopeial Forum 22, pp. 3065-3095]), the aerosols were shown to be monomodal when measured using a large volume inlet. The apparent large particle mode observed with the USP inlet seem rather to be droplets from the same monomodal distribution that have not fully evaporated. The complex interaction of the MDI plume and inlet configuration was described. Inlet design was shown to influence inlet deposition, measured particle size, and even deposition in the actuator mouthpiece. Inlet deposition was shown to be highly size-dependent with large droplets being collected more efficiently than smaller droplets.