In-vitro evaluation of pMDI spray development of HFA134a, HFA152a and HFO1234ze(E)

Lingzhe Rao, AJ Kusangaya, Nirmal Marasini, Hui Xin Ong, Benjamin Myatt, Phil Cocks, Damon Honnery, Paul Young, Daniel J. Duke

Research output: Chapter in Book/Report/Conference proceedingConference PaperOther


To assist the transition to alternative low GWP pMDI propellants, the current study performed high- speed imaging and droplet sizing of the near-orifice spray development of HFA-152a and HFO- 1234ze(E) based formulations. Conventional HFA-134a propellant was tested as the control. Placebo (pure HFA/HFO) and model solution (2 mg/mL drug dissolved in 8%w/w ethanol) formulations were measured, for each propellant. The results indicate larger droplets produced by HFA-152a and HFO- 1234ze(E) based placebo formulations at the near-orifice locations. HFA-152a also showed a wider and denser spray profile as compared to that of HFA-134a due to its low vapour pressure and density. The temporal spray development was also less stable and repeatable. HFO-1234ze(E) showed a similar spray profile and a more stable spray development compared to that of HFA-134a, however with reduced spray repeatability. The impact of changing propellants on spray development was reduced in model solution formulations. Both HFA-152a and HFO1234-ze(E) showed comparable spray profiles and measured droplet size to that of HFA-134a. The issue of low spray stability and repeatability persists in solutions, particularly for HFA-152a. These early results indicate that the transition to low GWP propellants is feasible, but further optimisation of the actuator design and formulation composition is needed.
Original languageEnglish
Title of host publicationProceedings of Drug Delivery to the Lungs Conference 2022
Number of pages4
Publication statusPublished - 2022
EventDrug Delivery to the Lungs Conference 2022 - Edinburgh International Conference Centre, Edinburgh, United Kingdom
Duration: 7 Dec 20229 Dec 2022


ConferenceDrug Delivery to the Lungs Conference 2022
Abbreviated titleDDL 2022
Country/TerritoryUnited Kingdom
Internet address

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