Effects and Safety of Different Dose of Bambuterol on Chinese COPD Patients

Inclusion Criteria: * COPD, the disease is under a stable phase * Giving written informed consent * Age 40 - 80 years (both inclusive) * Chinese ethnicity * 30% of predicated normal ≤Post bronchodilator FEV1 ≤ 70% of predicated normal * Post bronchodilator FEV1/FVC ≤ 70% (Note: post bronchodilator FEV1 will be tested 20-30 minutes after Salbutamol is used (inhaled via metered dose inhaler (MDI) and spacer). Exclusion Criteria: * COPD acute exacerbation 4 weeks prior to the enrollment * Patients with a history of asthma, allergic rhinitis, atopy * Use of disallowed drugs * Clinically relevant abnormal laboratory values suggesting an undiagnosed disease requiring further clinical evaluation (as assessed by the Investigator) * Severe psychiatric or neurological disorders * Congestive heart failure severity grade IV according to New York Heart Association (NYHA) * Haemodynamically significant cardiac arrhythmias or heart valve deformations * CT or X-ray findings indicating an acute pulmonary disease other than COPD (e.g. tuberculosis, severe bronchiectasis, tumors) * Severe immunological diseases (e.g. HIV infection, multiple sclerosis, lupus erythematosus, progressive multifocal leukoencephalopathy) * Severe acute infectious diseases (e.g. tuberculosis or acute hepatitis) * Any diagnosis of a malignant disease (except basal cell carcinoma) within 5 years before trial start * Alcohol or drug abuse within the past year * Suspected hypersensitivity to the Bambuterol or ingredients thereof, or any other contraindication for the use thereof * Pregnancy, breast feeding, planned oocyte donation or oocyte implantation * Participation in another trial (use of investigational product) within 30 days preceding the baseline visit V1 or re-entry of patients previously enrolled in this trial * Suffering from any concomitant disease that might interfere with trial procedures or evaluations