Fluorescence-enabled evaluation of nasal tract deposition and coverage of pharmaceutical formulations in a silicone nasal cast using an innovative spray device

Authors: Davide D’Angelo, Stefan Kooij, Frank Verhoeven, Fabio Sonvico, Cees van Rijn

Journal: Journal of Advanced Research, Volume 44, 2023

Abstract: This publication covers the evaluation of nasal deposition and deposition patterns of an innovative nasal spray nozzles generating slow velocity soft mists.

The methods involved studying the deposition pattern of a fluorescent liquid formulation in a transparent nasal cast under simulated inhalation flow conditions.

Image and fluorescence analysis were employed to assess the extent of deposition, while particle size distribution and initial droplet velocity were determined using laser diffractometry and high-speed camera techniques. The results demonstrated that uniform intranasal coverage was achieved with droplets of volume median particle size (Dv50) between 15 and 25 µm at airflow rates of 10-30 L/min.

Aerosol formulations could be uniformly deposited in nasal vestibule and turbinate cavity regions, with less than 10% passing beyond the nasopharyngeal region. In conclusion, the method allowed for determining nasal cast coverage across different regions using image and fluorometric analyses.

Droplet velocity emerged as a critical parameter for nasal cavity deposition. Standard swirl nozzles tended to deposit many droplets on the surface of the nasal vestibule, while soft mist nozzles produced smaller droplets at lower velocities, resulting in more uniform coverage.