Efficacy and Safety of 400 μg Twice Daily of Aclidinium Bromide vs. Placebo When Administered to Patients With Moderate to Severe Chronic Obstructive Pulmonary Disease (COPD)

Inclusion Criteria: * A diagnosis of stable moderate to severe COPD as defined by GOLD (the Global Initiative for Chronic Obstructive Lung Disease) guidelines(http://www.goldcopd.org); a postbronchodilator FEV1/forced vital capacity \[FVC\] ratio \< 70% and FEV1 ≥ 30% to \<80% of the predicted value. * Current or former cigarette smokers with a smoking history of at least 10 pack-years. Exclusion Criteria: * History or current diagnosis of asthma * Patients who have been hospitalized for an acute COPD exacerbation within 3 months prior to Visit 1 * Any respiratory tract infection (including the upper respiratory tract) or COPD exacerbation in the 6 weeks before Visit 1. * Patients with any clinically significant respiratory conditions other than COPD