A randomized, double-blind crossover study of change in post-dose lung function with a next generation propellant for metered dose inhalers in patients with asthma

<bold>Background</bold> Hydrofluoroalkane-134a (HFA) is a propellant used in many metered dose inhalers (MDIs) and has relatively high global warming potential (GWP). Due to environmental regulations restricting HFA use, new options are needed for MDIs. <bold>Aim</bold> Assess post-dose lung function with hydrofluoroolefin-1234ze (HFO), a low-GWP propellant, versus HFA in patients with asthma. <bold>Methods</bold> Participants (aged 18–45 years) with controlled asthma were randomized to single doses (4 inhalations) of HFO MDI and HFA MDI, separated by washout. The primary endpoint was change from baseline in forced expiratory volume in the first second area under the curve from zero to 15 minutes (FEV₁ AUC_0–15) post-dose. Secondary endpoints were bronchospasm (adverse event [AE] of asthma/bronchospasm or >15% decline in FEV₁ at 5 or 15 minutes post-dose with clinical symptoms) and safety (AEs). <bold>Results</bold> 52 participants (36 female) were included for analysis. Mean (standard deviation) baseline FEV­₁ was 2.97 (0.67) and 2.97 (0.65) L for HFO and HFA, respectively. HFO was non-inferior to HFA for post-dose change from baseline in FEV₁ AUC_0–15 (Table). No bronchospasm events were reported. AEs were reported in 2 participants with each propellant; none were serious or led to treatment discontinuation. <bold>Conclusion</bold> These data support use of HFO in MDIs as an alternative propellant with near-zero GWP. <fig><object-id>erj;64/suppl_68/PA3914/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>