The purpose of this extension study is to evaluate the long-term safety, tolerability, and efficacy of inhaled aclidinium bromide at two dose levels in patients with moderate to severe chronic obstructive pulmonary disease (COPD). This study will be 54 weeks in duration; a 52-week double-blind treatment period and 2 week follow-up phone call, following a 12 week lead-in study. All patients will be randomized from the lead-in study at one of two doses of aclidinium.

Inclusion Criteria:

• Completion of a lead-in study (NCT00891462)

Exclusion Criteria:

• Use or anticipated use of any medication prohibited in this study
• Evidence of abnormal clinical laboratory values, vital signs, or electrocardiographic (ECG) results or the presence of abnormities in physical examination findings
• The presence of anti-cholinergic effects (eg, dry mouth, urinary retention, narrow angle glaucoma)
• QTcB of >500 msec on both the pre-dose and post-dose ECG
• Women who are pregnant, intend to become pregnant, or are breast-feeding
• A life expectancy of less than 1 year
• Noncompliance with IP dosing and/or attending clinic visits during the lead-in study
• Significant interruption of double-blind therapy during the transition from the lead-in study into the extension study.