Inhalable formulations with cyclodextrins (CDs) as solubility and absorption enhancers show promise for pulmonary delivery. Thiolated hydroxypropyl-β-cyclodextrin (HP-β-CD-SH) has mucoadhesive properties, enhancing drug absorption. Moreover, it has self-aggregation capability, which could further improve absorption and drug stability, as well as reduce irritation. This study aims to stabilize CD nanoaggregates using bifunctional cross-linkers and evaluate their benefits for lung drug delivery compared to pristine HP-β-CD-SH. Methods: The effectiveness of cross-linked HP-β-CD-SH nanoparticles (HP-β-CD-SH-NP) was compared to transient nanoaggregates in enhancing the activity of dexamethasone (DMS) and olive leaf extracts (OLE). DMS, a poorly soluble drug commonly used in lung treatments, and OLE, known for its antioxidant properties, were chosen. Drug-loaded HP-β-CD-SH-NP were prepared and nebulized onto a lung epithelial Air–Liquid Interface (ALI) model, assessing drug permeation and activity. Results: HP-β-CD-SH with 25% thiolation was synthesized via microwave reaction, forming 150 nm nanoaggregates and stabilized 400 nm HP-β-CD-SH-NP. All carriers showed good complexing ability with DMS and OLE and were biocompatible in the lung ALI model. HP-β-CD-SH promoted DMS absorption, while stabilized HP-β-CD-SH-NP protected against oxidative stress. Conclusion: HP-β-CD-SH is promising for lung delivery, especially as stabilized nanoaggregates, offering versatile administration for labile molecules like natural extracts.

Acute respiratory distress syndrome (ARDS) is a severe complication of lung injuries, commonly associated with bacterial, fungal and viral infections, including SARS-CoV-2 viral infections. ARDS is strongly correlated with patient mortality and its clinical management is very complex, with no effective treatment presently available. ARDS involves severe respiratory failure, fibrin deposition in both airways and lung parenchyma, with the development of an obstructing hyaline membrane drastically limiting gas exchange. Moreover, hypercoagulation is related to deep lung inflammation, and a pharmacological action toward both aspects is expected to be beneficial. Plasminogen (PLG) is a main component of the fibrinolytic system playing key roles in various inflammation regulatory processes. The inhalation of PLG has been proposed in the form of the off-label administration of an eyedrop solution, namely, a plasminogen-based orphan medicinal product (PLG-OMP), by means of jet nebulisation. Being a protein, PLG is susceptible to partial inactivation under jet nebulisation. The aim of the present work is to demonstrate the efficacy of the mesh nebulisation of PLG-OMP in an in vitro simulation of clinical off-label administration, considering both the enzymatic and immunomodulating activities of PLG. Biopharmaceutical aspects are also investigated to corroborate the feasibility of PLG-OMP administration by inhalation. The nebulisation of the solution was performed using an Aerogen^® Solo^TM vibrating-mesh nebuliser. Aerosolised PLG showed an optimal in vitro deposition profile, with 90% of the active ingredient impacting the lower portions of a glass impinger. The nebulised PLG remained in its monomeric form, with no alteration of glycoform composition and 94% of enzymatic activity maintenance. Activity loss was observed only when PLG-OMP nebulisation was performed under simulated clinical oxygen administration. In vitro investigations evidenced good penetration of aerosolised PLG through artificial airway mucus, as well as poor permeation across an Air–Liquid Interface model of pulmonary epithelium. The results suggest a good safety profile of inhalable PLG, excluding high systemic absorption but with good mucus diffusion. Most importantly, the aerosolised PLG was capable of reversing the effects of an LPS-activated macrophage RAW 264.7 cell line, demonstrating the immunomodulating activity of PLG in an already induced inflammatory state. All physical, biochemical and biopharmaceutical assessments of mesh aerosolised PLG-OMP provided evidence for its potential off-label administration as a treatment for ARDS patients.

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.