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.