This is a randomized, placebo-controlled, double−blind study meaning neither the patient nor the study doctor will know which medication is being given. The study is randomized, meaning that participants will be randomly assigned to 1 of 3 treatment groups. To evaluate the efficacy, how the drug is absorbed in the blood stream and how safe is the study drug called AZD8871 when this is administered once daily during two weeks in patients with moderate to severe COPD