For all parts of the study, subjects in the VR647 group will receive VR647 Inhalation Suspension delivered by the VR647 Inhalation System (AKITA JET) with either a mouthpiece or a facemask. Similarly, for all parts of the study, subjects in the comparator group will receive approved doses of budesonide (Pulmicort Respules®) delivered by a conventional jet nebulizer (PARI VIOS) with either a mouthpiece or a facemask.
Part 1:
Subjects who fulfill the enrollment criteria will progress to a comparative single dose, 6-treatment, 6-period crossover trial. Subjects will receive 4 dose levels of VR647 Inhalation Suspension delivered by the VR647 Inhalation System (AKITA JET) (5, 10, 15 and 25 breaths, with targeted doses of 30, 60, 120 and 240 µg) and 2 dose levels of budesonide delivered by a conventional jet nebulizer (PARI VIOS) (0.5 and 1 mg). There will be a Washout Period between each dose of approximately 48 hours. Each subject will be randomized to treatment.
Part 2:
Following an approximate 7-day washout, the same cohort of subjects from Part 1 will progress to a comparative single dose, 6-treatment, 6-period crossover trial. There will be a Washout Period between each dose of approximately 48 hours. Each subject will be randomized to treatment in a 6-way crossover.
Part 3:
Subjects with mild asthma who fulfill the enrollment criteria (including those criteria specific to Part 3) will progress to a comparative single dose, 4-treatment, 4-period crossover trial conducted at a separate clinic from Parts 1 and 2. There will be a Washout Period between each dose of approximately 48 hours. This part of the trial can start before completion of Parts 1 and 2.