The urgency to replace the propellants currently in use with the new sustainable ones has given rise to the need for investigation and reformulation of pMDIs. The reformulation requires in-depth knowledge of the physico-chemical characteristics of the new propellants, which impact the atomization capacity and the plume geometry. Among the investigated propellants, HFA 152a, due to its lower vapor pressure and higher surface tension compared to HFA 134a, deliver larger particles and has a higher solvent capacity toward lipophilic drugs. On the other hand, HFO 1234ze seems to be more like HFA 134a, but with lower reproducibility of the generated spray, indicating a possible high susceptibility to variation in the consistency of the dose delivered. In addition, the hardware components currently in use are compatible with the new propellants. This allowed promising preliminary results in the re-formulation of pMDIs by academia and pharma companies. However, there is little information about the clinical studies required to allow the marketing of these new products. Overall, studies conducted so far show that the transition is technically possible, and the main obstacle will be represented by the full investment required to put the product on the market.

The aim of the project was to develop and characterise powders containing a probiotic (Lactiplantibacillus plantarum [Lpb. plantarum], Lacticaseibacillus rhamnosus, or Lactobacillus acidophilus) to be administered to the lung for the containment of pathogen growth in patients with lung infections. The optimised spray drying process for the powder manufacturing was able to preserve viability of the bacteria, which decreased of only one log unit and was maintained up to 30 days. Probiotic powders showed a high respirability (42%-50% of particles had a size < 5 µm) suitable for lung deposition and were proven safe on A549 and Calu-3 cells up to a concentration of 10⁷ colony-forming units/mL. The Lpb. plantarum adhesion to both cell lines tested was at least 10%. Surprisingly, Lpb. plantarum powder was bactericidal at a concentration of 10⁶ colony-forming units/mL on P. aeruginosa, whereas the other two strains were bacteriostatic. This work represents a promising starting point to consider a probiotic inhalation powder a value in keeping the growth of pathogenic microflora in check during the antibiotic inhalation therapy suspension in cystic fibrosis treatment regimen. This approach could also be advantageous for interfering competitively with pathogenic bacteria and promoting the restoration of the healthy microbiota.

Recent discoveries in the field of lung microbiota have enabled the investigation of new therapeutic interventions involving the use of inhaled probiotics. This review provides an overview of what is known about the correlation between airway dysbiosis and the development of local and systemic diseases, and how this knowledge can be exploited for therapeutic interventions. In particular, the review focused on attempts to formulate probiotics that can be deposited directly on the airways. Despite considerable progress since the emergence of respiratory microbiota restoration as a new research field, numerous clinical implications and benefits remain to be determined. In the case of local diseases, once the pathophysiology is understood, manipulating the lung microbiota through probiotic administration is an approach that can be exploited. In contrast, the effect of pulmonary dysbiosis on systemic diseases remains to be clarified; however, this approach could represent a turning point in their treatment.

This work illustrates the development of a dry inhalation powder of cyclosporine-A for the prevention of rejection after lung transplantation and for the treatment of COVID-19. The influence of excipients on the spray-dried powder’s critical quality attributes was explored. The best-performing powder in terms of dissolution time and respirability was obtained starting from a concentration of ethanol of 45% (v/v) in the feedstock solution and 20% (w/w) of mannitol. This powder showed a faster dissolution profile (Weibull dissolution time of 59.5 min) than the poorly soluble raw material (169.0 min). The powder exhibited a fine particle fraction of 66.5% and an MMAD of 2.97 µm. The inhalable powder, when tested on A549 and THP-1, did not show cytotoxic effects up to a concentration of 10 µg/mL. Furthermore, the CsA inhalation powder showed efficiency in reducing IL-6 when tested on A549/THP-1 co-culture. A reduction in the replication of SARS-CoV-2 on Vero E6 cells was observed when the CsA powder was tested adopting the post-infection or simultaneous treatment. This formulation could represent a therapeutic strategy for the prevention of lung rejection, but is also a viable approach for the inhibition of SARS-CoV-2 replication and the COVID-19 pulmonary inflammatory process.

Background: Cyclosporine is widely used to prevent transplant rejection; however, its systemic administration is associated with low bioavailability and a risk of severe adverse side effects. In the context of lung transplantation, local pulmonary delivery represents a promising strategy to reduce the required dose while enhancing local anti-inflammatory efficacy and limiting systemic toxicity. Methods: In this study, cyclosporine was encapsulated in liposomes coated with calcium phosphate to improve cellular uptake. The liposomal formulation was subsequently converted into a dry powder for inhalation to enable pulmonary administration, combining cyclosporine-loaded liposomes with a calcium phosphate coating, extending prior work on inhaled liposomal cyclosporine and mineral-coated liposomes into a single platform. The cyclosporine loading was optimised to achieve an efficient drug content in the final formulation. Results: The presence of the calcium phosphate coating on the liposomal surface was confirmed by the shift in zeta potential and by cryo-transmission electron microscopy. The resulting dry powder exhibited suitable aerodynamic properties for pulmonary delivery with a fine particle fraction of 33.6 ± 1.6%. In vitro biocompatibility studies performed on A549 epithelial cells and THP-1 monocytic cells demonstrated that the formulation did not affect cell viability. Furthermore, the formulation containing calcium phosphate-coated liposomes showed a stronger anti-inflammatory effect compared with both uncoated liposomal formulations and the corresponding raw material, consisting of a physical mixture of phospholipids and cyclosporine. Conclusions: Overall, despite limitations on respirability and efficacy that will require further in vivo studies, this calcium phosphate-coated liposomal dry powder could represent a promising strategy for targeted pulmonary delivery of cyclosporine, with potential to improve the prevention of lung transplant rejection while minimising systemic side effects.

1. The human lungs, once thought to be sterile, are now recognized to harbor a low-biomass microbial community whose composition is associated with respiratory health and disease [1]. Studies of th...