Preclinical Testing of a New Dry Powder Aerosol Synthetic Lung Surfactant Formulation and Device Combination for the Treatment of Neonatal Respiratory Distress Syndrome

<b><i>Background:</i></b> This study advanced the preclinical development of a new dry powder aerosol synthetic lung surfactant (SLS) product for neonatal respiratory distress syndrome (RDS) by integrating a multiple-actuation device and scalable spray-dried formulation, evaluating physicochemical and <i>in vitro</i> aerosol performance, and then comparing biological efficacy with the current clinical standard of high-volume liquid bolus instillation. <b><i>Methods:</i></b> A new high-dose air-jet dry powder inhaler was developed that was characterized by a variable-volume aerosolization chamber (D3 device) with the goal of unifying aerosol quality and emitted dose (ED) over multiple actuations. The SLS excipient enhanced growth dry powder formulation was advanced through production on a scalable nozzle-based spray dryer system (Mini Spray Dryer; MSD2 formulation). Physicochemical characterization of the formulation was performed along with <i>in vitro</i> aerosol testing of the new D3-MSD2 device and formulation combination. The optimized D3-MSD2 aerosol therapy was then evaluated in a rabbit model of severe RDS. <b><i>Results:</i></b> The new D3-MSD2 combination produced a small-particle aerosol with high fine particle fraction (FPF_{<5 µm} = 87.9%; FPF_{<2.5 µm} = 61.6%) and percent ED (77.4% of loaded). Additional <i>in vitro</i> testing highlighted consistent particle size (D_v50 = 1.6 µm) and ED across multiple actuations. In the animal model experiments, a total device-loaded formulation mass of 60 mg (delivered as 2x30 mg) produced a total phospholipid (PL) dose of 24 mg-PL/kg and a device ED of 18 mg-PL/kg compared with the 200 mg-PL/kg clinical dose of Curosurf liquid. <i>In vivo</i> response rate for the D3-MSD2 aerosol therapy was considerably more rapid with arterial oxygenation recovering 5-12 times faster than for liquid Curosurf. Biological response for the D3-MSD2 aerosol therapy was also superior with 2-fold improvement in final lung compliance compared with liquid Curosurf. <b><i>Conclusions:</i></b> The new D3-MSD2 aerosol therapy was found to be superior to clinical-practice liquid bolus instillation in the critical areas of required dose (order-of-magnitude reduction), delivery time, biological response rate, and efficacy.