Characterization of Spray-Dried Powders Using a Coated Alberta Idealized Nasal Inlet.

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery
• Biotechnology

Background:

• Dry powders enhance stability and reduce cold-chain needs for sensitive products like vaccines.
• Intranasal delivery offers an alternative administration route, bypassing the cold chain.
• The Alberta Idealized Nasal Inlet (AINI) is a model for evaluating nasal powder delivery.

Purpose of the Study:

• To assess the *in vitro* deposition of spray-dried trehalose powders in the AINI.
• To investigate the effect of primary particle size on nasal powder deposition and lung exposure.
• To evaluate the AINI's utility for characterizing intranasal powder delivery.

Main Methods:

• Spray-dried trehalose powders (10, 20, 40 mg) with different particle sizes were loaded into single-dose devices.
• Laser diffraction measured powder particle size and dispersed aerosol characteristics.
• The AINI was coated to prevent particle bounce, and powders were dispersed at 7.5 or 15 L/min.
• Powder deposition was quantified in AINI regions, a preseparator, and a filter (lung surrogate) using LC-MS.

Main Results:

• AINI coating effectively mitigated particle bounce.
• Nasal deposition patterns were consistent across tested flow rates (7.5 vs. 15 L/min).
• Larger primary particle size (Powder B) resulted in reduced lung deposition (negligible) compared to smaller particles (Powder A, up to 7%).
• Both powders showed significant deposition in the turbinates and nasopharynx.

Conclusions:

• Particle size is a critical factor for controlling intranasal powder deposition and lung exposure.
• Larger particles enhance peripheral nasal deposition while minimizing lung deposition.
• Optimized spray-dried powders can target nasal airways and reduce pulmonary exposure, making them suitable for vaccine delivery.