Study to Evaluate the Pharmacokinetic Profile of Salbutamol Delivered by Unit Dose Dry Powder Inhaler (UD-DPI) Compared to the Diskus and Metered Dose Inhaler (MDI) in Healthy Volunteers.

This is an open-label, two part, six period- cross over, randomised, single dose, single centre study in healthy subjects. This is the first clinical study for the UD-DPI. This study is divided into two parts. Part A will ascertain whether the pharmacokinetic (PK) of salbutamol delivered via the UD-DPI is comparable to the salbutamol delivered via the Diskus or MDI. For this reason four treatment doses consisting of three dose strength and two percentage blends will be assessed in Part A delivered via UD-DPI. Part A will also provide preliminary PK variability estimates to allow for better sample size/precision calculations for Part B. Part B will explore whether the UD-DPI has a pharmacokinetic exposure profile that is comparable to either Diskus or MDI in the presence of the charcoal block.