The overall objective is to asses the bronchodilator effect of Tiotropium/Salmeterol/Fluticasone combination delivered via Discair® twice daily as compared with original products Seretide Diskus 500 mcg Inhalation Powder twice daily and Spiriva 18 mcg Inhalation Powder once daily free combination treatment in patients with stable moderate to severe COPD.

Spirometric measurements will be performed totally at 15 different time points at pretreatment and post-treatment (pre-dose, 15. min, 30. min, 1. hr, 2. hr, 4.hr, 8.hr and 12.hr) during the first treatment day and at 16 different time points (15. min, 30. min, 1. hr, 2. hr, 4.hr, 6 hr, 8.hr and 12.hr) during the second treatment day.

The overall objective is to asses the bronchodilator effect of Tiotropium/Salmeterol/Fluticasone combination delivered via Discair® twice daily as compared with original products Seretide Diskus 500 mcg Inhalation Powder twice daily and Spiriva 18 mcg Inhalation Powder once daily free combination treatment in patients with stable moderate to severe COPD.

For formerly diagnosed patients who met all the inclusion criteria and 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.

Patients (following run-in period for formerly diagnosed patients) will be randomly assigned to receive Tiotropium/Salmeterol/Fluticasone fixed dose combination as dry powder inhalation delivered via Discair® twice daily or Seretide Diskus 500 mcg Inhalation Powder twice daily and Spiriva 18 mcg Inhalation Powder once daily free combination for 2-days treatment period.

Patients will be evaluated at 4 consecutive visits: baseline (enrollment), screening, treatment and after treatment.

Spirometric measurements will be performed totally at 15 different time points at pretreatment and post-treatment (pre-dose, 15. min, 30. min, 1. hr, 2. hr, 4.hr, 8.hr and 12.hr) during the first treatment day and at 16 different time points (15. min, 30. min, 1. hr, 2. hr, 4.hr, 6 hr, 8.hr and 12.hr) during the second treatment day.

Inclusion Criteria:

• Patients aged ≥40 years with COPD diagnosis according to the GOLD (The Global Initiative for Chronic Obstructive Lung Disease) strategy.
• Patients who have symptomatic stable moderate to severe COPD diagnosis with post-bronchodilator FEV1/FVC ratio <0.70, and FEV1 <80% of predicted normal value at screening visit.
• Patients with a mMRC score ≥2
• Current smokers or ex-smokers with a smoking history of at least 10 pack-years
• Patients who have an exacerbation within least a year and no exacerbation within last 4 weeks
• Females patients with childbearing potential using effective birth control method
• Patients who has a capability of communicate with investigator
• Patients who accept to comply with the requirements of the protocol
• Patients who signed written informed consent prior to participation

Exclusion Criteria:

• History of hypersensitivity to drugs contains long acting beta-2 agonists, corticosteroids, anticholinergics or lactose.
• History of asthma or significant chronic respiratory diseases except COPD.
• Patients who had COPD exacerbation or lower respiratory track infections that required antibiotic, oral or parenteral corticosteroid treatment within 4 weeks prior to screening visit or during run-in period.
• Patients with serum potassium level ≤ 3.5 mEq/L or >5.5 mEq/L
• Patients who used systemic corticosteroids or immunosupresants within 4 weeks prior to study onset
• Patients who have a history of myocardial infarction, hearth failure, acute ischemic coroner disease or severe cardiac arrhythmia requiring treatment within least 6 weeks
• Patients who have lung cancer
• Patients who had lung volume reduction operation
• Patients who had live attenuated vaccines within 2 weeks prior to screening visit or during run-in period
• Women patients who are pregnant or nursing
• History of allergic rhinitis or atopy
• Known symptomatic prostatic hypertrophy requiring drug therapy or operation