Investigation of powder properties and application aspects impacting nasal deposition of spray-dried powders in a nasal cast.

In this study, spray-dried formulations differing in morphology (spherical and wrinkled), surface polarity (hydrophilic and hydrophobic), and size (20-30 µm and 3 µm) were evaluated in a nasal cast to assess their deposition profiles. The objective was to identify how formulation properties and application aspects influence the deposition profile. For this purpose, the formulations were administered at different application angles (45° and 60°), fill weights (20 mg and 40 mg), and airflow rates (0 L/min and 15 L/min) in conjunction with a UDS powder device. The results indicate a more posterior deposition profile for 45° compared to 60° due to increased deposition in the turbinate region; conversely, deposition profiles between fill weights were comparable. Application with simultaneous airflow should be avoided because of an increasing postnasal fraction. No influence of morphology could be observed, but for the surface polarity an influence was apparent, if the powder was applied with a simulated inspiration. In these cases, a hydrophobic formulation was better dispersible than a hydrophilic formulation, which led to an increased postnasal fraction. A particle size for pulmonary application demonstrated comparable results to nasal formulations with respect to the turbinate deposition but exhibited a high postnasal fraction for hydrophobic formulations.