This is a multiple dose, randomised, parallel, double blind, double dummy, multicentre and multinational Phase III study to determine the efficacy and safety of Aclidinium bromide/Formoterol fumarate compared with individual components and placebo and Aclidinium bromide compared with Placebo when administered to patients with stable Chronic Obstructive Pulmonary Disease (COPD).

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

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal. All request will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA Pharma Data Sharing Principles. For details of our timelines, please rerefer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

When a request has been approved AstraZeneca will provide access to the de-identified individual patient-level data in an approved sponsored tool . Signed Data Sharing Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information. Additionally, all users will need to accept the terms and conditions of the SAS MSE to gain access. For additional details, please review the Disclosure Statements at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.