Main Inclusion Criteria:

• Written informed consent
• Patients with a history of chronic obstructive pulmonary disease (COPD) as defined by the GOLD criteria (2003)
• FEV1/FVC ratio (post bronchodilator) smaller or equal 70%
• FEV1 (post bronchodilator) 30-80% of predicted
• Fixed airway obstruction
• Current smoker or former smoker (smoking cessation at least one year ago) with a smoking history of at least 10 pack years
• Clinically stable COPD within 4 weeks prior to baseline visit
• Availability of a chest x-ray

Main Exclusion Criteria:

• COPD exacerbation indicated by a treatment with systemic glucocorticosteroids
• Lower respiratory tract infection
• Diagnosis of asthma
• Known alpha-1-antitrypsin deficiency
• Need for long term oxygen therapy defined as longer or equal 16 hours/day
• Clinically relevant abnormal laboratory values suggesting an unknown disease and requiring further clinical evaluation (as assessed by the investigator)
• Known infection with HIV, active hepatitis and/or liver insufficiency (according to the Child Pugh score A or worse)
• Diagnosis or history of cancer
• Clinically significant cardiopulmonary abnormalities
• Pregnancy, breast feeding, oocyte donation or oocyte implantation planned during the trial
• Female patients of childbearing potential, not using reliable method of contraception for the entire study duration, post-menopausal > 1 year or who are not using any other method considered sufficiently reliable by the investigator in individual cases
• Participation in another study (use of investigational product) within 30 days preceding the baseline visit or re-entry of patients already enroled in this trial
• Alcohol or drug abuse
• Inability to follow the study procedures due to e.g., language problems, physiological disorders
• Use of not allowed drugs
• Suspected hypersensitivity to the study medication or rescue medication