A Study to Compare the Relative Potency of Salbutamol Administered Via Metered Dose Inhalers (MDI) Containing Propellants HFA-152a to HFA-134a in Mild Asthmatics Aged 18 to 65 Inclusive

A single 100, 200 or 400 μg dose, given as 1, 2 or 4 × 100 μg actuations (exvalve) at 20 second intervals.

A single 100, 200 or 400 μg dose, given as 1, 2 or 4 × 100 μg actuations (exvalve) at 20 second intervals.

A single placebo HFA-152a suspension or placebo HFA-134a suspension dose, given as at 20 second intervals.