This is a randomized, double-blind, placebo-controlled, parallel arm study. The study population will consist of subjects, 35 to 75 years of age, with a diagnosis of moderate to severe COPD per Global Initiative for Chronic Obstructive Lung Disease guidelines (GOLD, 2011). The primary analysis will compare each of the EP-101 (SUN101) dose groups to placebo with respect to the change from baseline in morning trough FEV1 on Day 29. Trough FEV1 is defined as the mean of the two FEV1 values obtained at 23 hours 30 minutes and 24 hours after Day 28 AM dose (ie, approximately 12 hours after the previous PM dose).