Abstract
Inhalation delivery of biologics as dry powders offers a promising alternative to liquid formulations, eliminating the need for cold storage. However, controlling particle properties for efficient lung delivery is challenging. While spray drying (SD) has been successfully used, it often requires excipients not approved for inhalation. In this study, spray freeze drying (SFD) was explored as an alternative technology. Human immunoglobulin G (hIgG) was used as a model molecule and dried in a mannitol-based formulation, approved for inhalation delivery. The effect of nozzle diameter (50–100 μm) and solids' concentration (5–10 %(w/w)) were investigated. Despite their large size (20–300 μm), SFD particles achieved fine particle doses over emitted doses (FPD/ED) up to 80 %, which was attributed to their low density (<0.52 g/cm3). The study highlights the SFD potential to enhance the aerodynamic performance of dry powder formulations for inhalation delivery, as demonstrated in comparative tests with SD.

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