Introduction
Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by chronic bronchitis, emphysema, and remodeling. Its prevalence is increasing worldwide; however, there are few effective therapies, and none of the treatments currently available prevent the progression of the disease or target all of the hallmark features. The development and progression of COPD are heterogeneous, which has hampered the development of new therapies.

Areas covered
In this review, we cover the emergence of the improvement of existing classes of drugs including glucocorticoids, β2-adrenoceptor agonists, phosphodiesterase inhibitors, PDE4 selective inhibitors, PDE3/PDE4 inhibitors, protease inhibitors, recombinant α1-antitrypsin and neutrophil elastase inhibitors. We also highlight new compounds that target recently identified mechanisms of COPD, new dual-action muscarinic antagonists, and β2-agonists, kinase inhibitors, cytokine modifiers, chemokines modifiers, NF-κB inhibitors, senolytics, antioxidants, inhaled antiviral agents, anti-fibrotic compounds, and compounds stimulating lung regeneration.

Expert opinion
Given the myriad of potential therapeutic avenues that can be pursued, careful consideration of the phenotypes/endotypes of COPD patients will be important for personalized treatment options in the future, and a full understanding of disease mechanisms in patient subsets will ensure these emerging therapies are targeted appropriately.