Aerosol of Enoximone/Hydroxypropyl-β-Cyclodextrin Inclusion Complex, Biopharmaceutical Evidence for ARDS Applicability

Background: Phosphodiesterase (PDE) inhibitors are gaining interest in the context of pulmonary pathologies. In particular, the PDE3 inhibitor enoximone (ENXM) has shown potential relative to the cure of asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory distress syndrome (ARDS). Despite its administration via inhalation being planned for use against COVID-19 related ARDS (C-ARDS), presently, no inhalable medicine containing ENXM is available. Objectives: This study aims to develop a new formulation suitable for pulmonary administration of ENXM. Methods: A solution for nebulization, based on the complex between ENXM and Hydroxypropyl-β-Cyclodextrin (HPβCD) (ENXM/HPβCD) is developed. The obtained solution is characterized in terms of aerodynamic distributions and biopharmaceutical features. Results: The evaluation of the aerosol droplets indicates a good bronchi–lung distribution of the drug. Biological evaluations of the air–liquid interface (ALI) in an in vitro lung cell model demonstrates that ENXM/HPβCD is capable of a local direct effect, increasing intracellular cyclic adenosine monophosphate (cAMP) levels and protecting from oxidative stress. Conclusions: This study offers a promising advance in the optimization of enoximone delivery to the lungs.