Study Comparing Dual Combination of Product (Budesonide and Formoterol) Given Via Two Different Inhalers. To See Which One Results in the Best Effect on Breathing.

This is a Randomized, Open-Label, Two Period Crossover, Chronic Dosing, 1-Week, Pilot Study to Assess the Efficacy and Safety of Budesonide and Formoterol Fumarate Inhalation Aerosol Administered with a Spacer Compared with Symbicort® Turbuhaler® in Subjects with Severe to Very Severe Chronic Obstructive Pulmonary Disease and Low Peak Inspiratory Flow to assess lung function