Study to Assess Efficacy and Safety of Aclidinium Bromide and Aclidinium Bromide/Formoterol Fumarate in Stabile COPD Patients

Inclusion Criteria: * 1\. Adult male or non-pregnant, non-lactating female patients aged ≥40 * 2\. Patients with a diagnosis of COPD prior to Visit 1 (screening) * 3\. Patients with moderate to severe stable COPD (Stage II or Stage III) at Visit 1: post-bronchodilator FEV1 ≥30% and \< 80% and post-bronchodilator FEV1/Forced vital capacity (FVC) \< 70% * 4\. Current or former smokers with a smoking history of ≥ 10 pack-years * 5\. Patients able to perform repeatable pulmonary function testing for FEV1 according to the American Thoracic Society (ATS)/European Respiratory Society (ERS) 2005 criteria at Visit 1(screening) * 6\. Patients who understand the study procedures and are willing to participate in the study as indicated by signing the informed consent Exclusion Criteria: * 1\. Involvement in the planning and/or conduct of the study (applies to AstraZeneca staff and/or site staff) or patients employed by or relatives of the employees of the site or sponsor. * 2\. Previous enrolment or randomisation in the present study * 3\. History or current diagnosis of asthma * 4\. Any respiratory tract infection (including the upper respiratory tract) or COPD exacerbation (including the mild COPD exacerbation) within 6 weeks prior to screening or during the run-in period * 5\. Patients hospitalized for COPD exacerbation (an emergency room visit for longer than 24 hours will be considered a hospitalization) within 3 months prior to screening and during the run-in period * 6\. Clinically significant respiratory conditions other than COPD * 7\. Patients who in the Investigator's opinion may need to start a pulmonary rehabilitation program during the study and/or patients who started/finished it within 3 months prior to screening * 8\. Use of long-term oxygen therapy (≥15 hours/day) * 9\. Patient who does not maintain regular day/night, waking/sleeping cycles including night shift workers * 10\. Clinically significant cardiovascular conditions * 11\. Patients with Type I or uncontrolled Type II diabetes, uncontrolled hypo-or hyperthyroidism, hypokalaemia, or hyperadrenergic state, uncontrolled or untreated hypertension * 12\. Patients with QT corrected interval (QTc) using Fridericia formula (QTcF) (QTc=QT/ Duration in milliseconds between two R peaks of two consecutive QRS complexes (RR1/3) \>470 msec as indicated in the centralised reading report assessed at Screening (Visit 1) * 13\. Patients with clinically significant abnormalities in the clinical laboratory tests, ECG parameters (other than QTcF) or in the physical examination at Visit 1 (screening) * 14\. Patients with abnormal liver function tests defined as Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), or total bilirubin ≥ 2.5 times upper limit of normal ranges at screening * 15\. Patient with known non-controlled history of infection with human immunodeficiency virus and/or active hepatitis * 16\. Patient with a history of hypersensitivity reaction to inhaled anticholinergic drugs, sympathomimetic amines, inhaled medication or any component thereof * 17\. Patient with known narrow-angle glaucoma, symptomatic bladder neck obstruction, acute urinary retention, or patients with symptomatic non-stable prostatic hypertrophy * 18\. History of malignancy of any organ system (including lung cancer), treated or untreated, within the past 5 years other than basal or squamous cell skin cancer * 19\. Any other serious or uncontrolled physical or mental dysfunction * 20\. Patients with a history (within 2 years prior to Visit 1 (screening) of drug and/or alcohol abuse that may prevent study compliance based on the Investigator judgment * 21\. Patients unlikely to be cooperative or cannot comply with the study procedures * 22\. Patients treated with any investigational drug within 30 days (or 6 half-lives, whichever is longer) prior to screening * 23\. Patients who intended to use any concomitant medication not permitted by this protocol or who had not undergone the required washout period for a particular prohibited medication * 24\. Patients unable to give consent, or patients of consenting age but under guardianship, or vulnerable patients * 25\. Any other conditions that, in the Investigator's opinion, might have indicated the patient to be unsuitable for the study