Ensifentrine (RPL554): an inhaled 'bifunctional' dual PDE3/4 inhibitor for the treatment of asthma and chronic obstructive pulmonary disease.

Ensifentrine (RPL554), an inhaled 'bifunctional' dual phosphodiesterase 3/4 inhibitor that exhibits both bronchodilator and anti-inflammatory activities, provides a new option in the treatment of chronic obstructive pulmonary disease (COPD) and other inflammatory airway diseases that are under clinical development. Ensifentrine appears to be initially under development for the treatment of COPD although it is not yet clear whether it should be understood as an add-on therapy in patients for the treatment of acute exacerbations of COPD or for the regular maintenance treatment of patients either alone, or on top of existing drug classes.