The overall objective is to asses the bronchodilator effect of once daily Tiotropium/Formoterol combination delivered via Discair® by comparing Tiotropium (q.d.) monotherapy delivered via Handihaler and tiotropium (q.d.) delivered via Handihaler + formoterol (b.i.d) delivered via Aerolizer free combination treatment in patients with stable moderate to severe COPD.~Patients will be randomly assigned to receive Tiotropium/Formoterol combination as dry powder for inhalation by Discair® (test inhaler, n = 29) or Tiotropium as dry powder capsule for inhalation by HandiHaler or tiotropium dry powder capsule for inhalation by HandiHaler + formoterol as dry powder capsule for inhalation by Aerolizer. Patients will be evaluated at 4 consecutive visits: baseline (enrollment), screening, treatment, and 24h after treatment.~For newly diagnosed and formerly diagnosed patients who are not on COPD medication, the screening visit will be performed on the day of enrollment. For formerly diagnosed patients receiving COPD treatment, the day of the screening visit will be based on the completion of a run-in period, with the length determined by the specific medication. During the run-in period, salbutamol (100 µg inhaler) will be prescribed as a rescue medication.~Spirometric measurements (FEV1, FVC) will be performed for a period of 24 h at 12 different times: pre-treatment (15 min prior to the first dose) and post-treatment (30. min, 60 min [1 hr], 120 min [2 hr], 180 min [3 hr], 240 min [4 hr], 360 min [6 hr], 480 min [8 hr], 600 min [10 hr], 720 min [12 hr], 840 min [14 hr],1440 min [24 hr].
The overall objective is to asses the bronchodilator effect of once daily Tiotropium/Formoterol combination delivered via Discair® by comparing Tiotropium (q.d.) monotherapy delivered via Handihaler and tiotropium (q.d.) delivered via Handihaler + formoterol (b.i.d) delivered via Aerolizer free combination treatment in patients with stable moderate to severe COPD.~Spirometric measurements (FEV1, FVC) will be performed for a period of 24 h at 12 different times: pre-treatment (15 min prior to the first dose) and post-treatment (30. min, 60 min [1 hr], 120 min [2 hr], 180 min [3 hr], 240 min [4 hr], 360 min [6 hr], 480 min [8 hr], 600 min [10 hr], 720 min [12 hr], 840 min [14 hr],1440 min [24 hr].