The discovery and development of ensifentrine: A novel inhaled dual PDE3/4 inhibitor having ‘bifunctional’ bronchodilator and anti‐inflammatory activity

Ensifentrine (formerly called RPL 554) is a novel, first in class, inhaled bifunctional dual PDE3/4 inhibitor for the treatment of chronic respiratory diseases. Ensifentrine exhibits both bronchodilation via PDE3 inhibition and anti‐inflammatory activity via PDE4 inhibition. Following extensive preclinical and clinical investigations, ensifentrine was recently approved by the FDA as a treatment for patients with chronic obstructive pulmonary disease (COPD). It is anticipated that this novel drug will provide a useful addition to the available treatments for pulmonary diseases.