The Airway Revolution: Proteins and Probiotics in Pulmonary Drug Delivery

Introduction: Biologics currently account for more than 20% of all global pharmaceutical sales. The inhalation pathway of biological drugs is an appealing alternative to parenteral route but poses new challenges, especially related to the maintenance of the structure and activity of the drug post-manufacturing and during the shelf-life. Oral probiotics have shown potential in alleviating pulmonary diseases such as asthma, COPD, and cystic fibrosis. This presentation will introduce an innovative approach in which lactobacilli are incorporated into inhalable particles designed to deposit directly in the lungs, where they may correct imbalances in local microflora. Moreover, the talk will illustrate formulation strategies to produce effective and respirable GLP1 powders.

Methods: Inhalation powders including pramlintide, GLP-1 receptor agonist semaglutide (SMG) or lattobacilli were produced by spray-drying. Powders were characterised in terms of drug content, respirability and morphology. Furthermore, specific analyses that investigate the maintenance of the structure and the activity of the biological drug such as SDS page, ELISA were carried out. For PK studies SMG were dosed via SC or intratracheal (IT) administration to Sprague-Dawley rats. For the SC study, SMG was solubilized in PBS ad injected at the dose of 100 nmol/kg (=400 µg/kg) and for IT SMG formulated as powder was also administered at the same dose, after animal anesthetization.

Results: Trehalose and L-leucine has been proven to be beneficial on the quality attributes of the pramlintide and SMG powder. Fine particle fraction of pramlintide DPI was about 60% and MMAD of 1.5 µm. Pramlintide conjugates were investigated aiming to improve the absorption of derivatives with extended half-life. These conjugates demonstrated improved pharmacodynamic effects compared to free pramlintide in reducing food intake and body weight gain when administered subcutaneously. However, this outcome was not observed with intratracheal (IT) administration, where the free DPI pramlintide proved to be the most effective, achieving approximately a 10% reduction in body weight within 7 days of observation
From the PK study, the plasma concentration profile of SMG indicates that powder formulation administered via IT route was rapidly absorbed, reaching a Cmax of 0.341 µg/mL at a Tmax of 3 hours. When administered SC, SMG reached a Cmax of 0.406 µg/mL at a Tmax of 4 hours, with a range of 2–4 hours. As expected, the depot effect of SC injection resulted in a prolonged and delayed exposure to SMG, as reflected in the PK profile. This translated into an AUC statistically significantly higher than that observed after IT administration.
The same particle engineering technology used to obtain peptide particles with peculiar morphology has been applied to obtain corrugated and highly respirable particles (FPF=43%) containing probiotics. The addition of the raffinose as prebiotic in the Lpb. plantarum formulation protected the viability after 30-days storage at room temperature. The powder had a MMAD of 5 µm, suitable for this specific application that do not require particle penetration into the distal part of the lungs. The powders showedto be antibacterial against different strains of P. aeruginosa and anti-inflammatory on A549 cells (LPS inflamed).