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Mucociliary Clearance Following a Next-Generation Propellant Versus Hydrofluoroalkane-134a via Pressurized
Scott H Donaldson1, Kirby L Zeman1, Alan Bell2
1Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Journal of Aerosol Medicine and Pulmonary Drug Delivery
|July 16, 2026
Summary
This study found that hydrofluoroolefin-1234ze (HFO-1234ze) has no clinically significant impact on mucociliary clearance (MCC) compared to hydrofluoroalkane-134a (HFA-134a). This supports the transition to lower global warming potential propellants for metered-dose inhalers.
Area of Science:
- Respiratory medicine
- Environmental science
- Pharmacology
Background:
- Pressurized metered-dose inhalers (pMDIs) use propellants like HFA-134a, contributing to global warming.
- Transitioning to lower global warming potential (GWP) propellants, such as HFO-1234ze, is crucial for environmental sustainability.
- HFO-1234ze offers a 99% lower GWP than HFA-134a, supporting regulatory requirements for greener inhaler technology.
Purpose of the Study:
- To assess the impact of the lower-GWP propellant HFO-1234ze on mucociliary clearance (MCC) in healthy individuals.
- To compare the safety and efficacy of HFO-1234ze against the current standard propellant HFA-134a.
- To provide data supporting the registration of pMDIs utilizing HFO-1234ze.
Main Methods:
- A randomized, double-blind, multicenter, crossover study involving healthy participants aged 18-60.
- Participants received HFO-1234ze and HFA-134a pMDIs over two 7-day periods with a washout interval.
- Mucociliary clearance (MCC) was measured using 99mTc-labeled colloid and gamma camera imaging, assessing changes from baseline.
Main Results:
- No clinically relevant impact on MCC60 (60-minute clearance) was observed between HFO-1234ze and HFA-134a.
- A statistically significant difference was noted for MCC3h (3-hour clearance), favoring HFA-134a, though clinical relevance requires further evaluation.
- No unexpected safety or tolerability issues were identified for HFO-1234ze.
Conclusions:
- HFO-1234ze demonstrates comparable safety and no clinically relevant impact on mucociliary clearance versus HFA-134a in healthy subjects.
- This finding supports the use of HFO-1234ze as a sustainable alternative propellant in pMDIs.
- Further research may explore long-term effects and patient populations with respiratory diseases.
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