Development of a High-Dose Infant Air-Jet Dry Powder Inhaler (DPI) with Passive Cyclic Loading of the Formulation

Purpose The objective of this study was to incorporate a passive cyclic loading strategy into the infant air-jet dry powder inhaler (DPI) in a manner that provides high efficiency aerosol lung delivery and is insensitive to powder mass loadings and the presence of downstream pulmonary mechanics. Methods Four unique air-jet DPIs were initially compared and the best performing passive design (PD) was selected for sensitivity analyses. A single preterm in vitro nose-throat (NT) model, air source, and nasal interface were utilized throughout. While the majority of analyses were evaluated with a model spray-dried excipient enhanced growth (EEG) formulation, performance of a Surfactant-EEG formulation was also explored for the lead DPI design. Results Two devices, PD-2 and PD-3, evaluated in the preterm model achieved an estimated lung delivery efficiency of 60% with the model EEG formulation, and were not sensitive to the loaded dose (10–30 mg of powder). The PD-3 device was also unaffected by the presence of downstream pulmonary mechanics (infant lung model) and had only a minor sensitivity to tripling the volume of the powder reservoir. When using the Surfactant-EEG formulation, increasing the actuation flow rate from 1.7 to 4.0 L/min improved lung delivery by nearly 10%. Conclusions The infant air-jet DPI platform was successfully modified with a passive cyclic loading strategy and capable of providing an estimated > 60% lung delivery efficiency of a model spray-dried formulation with negligible sensitivity to powder mass loading in the range of 10–30 mg and could be scaled to deliver much higher doses.