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Experimental and Theoretical Investigations of pMDI Atomization and Plume Characteristics Using Alternative Propellants

Stein SW, Myatt BJ, Cocks P, Wrigglesworth S, Versteeg HK, Gavtash B.

Respiratory Drug Delivery 2021. Volume , 2021: 15-26.

Abstract:

Pressurized metered dose inhalers (pMDIs) remain popular devices used for the treatment of respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD). New low global warming potential (GWP) propellants are currently being explored as part of efforts to reduce the carbon footprint of the pMDI. Little is understood about the atomization and spray plume characteristics of pMDIs utilizing these new propellants. A series of experiments and theoretical modeling are presented that characterize the performance of pMDIs using HFA- 134a, HFA-227 and the new low GWP propellants HFA-152a and HFO-1234ze. Our findings indicate that there are some differences in plume characteristics for HFA-152a pMDIs compared to currently used propellants that could impact patient acceptance. Results indicate that the initial size of atomized droplets is larger for pMDIs using HFA-152a and HFO-1234ze compared to pMDIs using HFA-134a and HFA-227, but there were limited differences in aerodynamic particle size distribution (APSD) measured by cascade impaction. Further research is needed to understand these observations.