The study will assess the degree of bronchoprotection provided by the ultra long-acting beta2 agonist vilanterol against methacholine-induced bronchoconstriction.
This will be a double-blind, three-way crossover study comparing combination vilanterol+fluticasone with fluticasone monotherapy and a placebo (vilanterol is not available as a monotherapy). The order in which the treatments are given will be randomized and each treatment will be separated by a minimum one-week washout. Fifteen asthmatic participants will be recruited from the local community. Methacholine challenge testing (MCT) with the two-minute tidal breathing protocol will be used to quantify the bronchoprotective effects (if any) of each treatment against methacholine-induced bronchoconstriction. Each participant will undergo a total of nine methacholine challenges. After a baseline methacholine challenge, the randomized treatment (identity unknown to investigator or participant) will be administered through an Ellipta® (multi-dose dry powder inhaler). Thirty minutes following treatment administration, a second methacholine challenge will be performed. At 24 hours post-treatment, each participant must re-visit the lab for one methacholine challenge. The same process will be followed for each treatment.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
17
Same as vilanterol arm description
Same as fluticasone arm description
Same as placebo arm description
Asthma Research Lab - University of Saskatchewan
Saskatoon, Saskatchewan, Canada
Change from baseline methacholine PC20 (bronchoprotection) at 30 min post-treatment
assessed by dose shift of geometric mean methacholine PC20 data
Time frame: baseline versus 30 min post-treatment
Change from baseline methacholine PC20 (bronchoprotection) at 24 hours post-treatment
assessed by dose shift of geometric mean methacholine PC20 data
Time frame: baseline versus 24 hours post-treatment
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