A randomized, double-blind, multi-site, two-way crossover study to assess the effect on MCC and safety of HFO propellant compared to HFA propellant in healthy participants. Mucociliary clearance will be determined after 1 week of twice daily (BID) administration of HFO MDI (test) and HFA MDI (reference).
The study will comprise a Screening Period 7 to 14 days prior to first dosing; Two Treatment Periods (TPs) of 7 days each (+ up to 3 days), with a 7 to 14 day Washout Period between the 2 TPs; and a final safety Follow-up Visit 5 to 7 days after the final dose administration in TP2.
Participants will receive treatments in 1 of 2 possible treatment sequences: A followed by B, or B followed by A.
Study treatment will be administered via MDI device as 6 inhalations BID (every morning and evening approximately 12 hours apart):
Treatment A: HFO MDI; 6 inhalations per dose - test formulation Treatment B: HFA MDI; 6 inhalations per dose - reference formulation