The study is divided into 3 periods, a screening/run-in period (run-in for 28 days), a treatment period (24 weeks), and a follow-up period (1 week after the end-of-treatment visit). The qualified subjects will be randomly assigned to the Ensifentrine group or placebo group in a ratio of 5:3, stratified by maintenance therapy in a stable background long-acting muscarinic antagonist (LAMA) or long-acting β2 agonist (LABA) (yes or no) and smoking status (current or past smokers). The Ensifentrine group will receive Ensifentrine 3mg BID nebulizer, and the placebo group will receive placebo nebulizer. The treatment will be lasted given for 24 weeks in both groups.~During treatment, lung function, COPD symptoms, quality of life and other parameters of subjects will be assessed at baseline, week 6, 12, and 24, and the safety will also be assessed over 24-week treatment period and the follow-up period. PK characteristics and dose-response relationship of Ensifentrine will be analyzed for all patients using sparse sampling.
This is a multi-center, randomized, double-blind, placebo-controlled, parallel-group clinical study, which aims to evaluate the efficacy, safety, and PK characteristics of Ensifentrine 3 mg twice daily (BID) for 24 weeks treatment of moderate to severe COPD.