Efficacy and Safety of Oral Roflumilast Taken Once Daily in Patients Older Than 40 Years With Chronic Obstructive Pulmonary Disease (BY217/M2-119)

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