  In addition to topical delivery, nasal sprays offer an alternative drug
administration route to the systemic circulation, therefore avoiding the need
for painful, invasive delivery techniques. Studies on the efficacy of nasal
drug delivery to date have been conflicting despite its potential. In
particular computational studies, e.g. Computational Fluid Dynamics (CFD), of
nasal spray deposition require realistic initial spray conditions, which are
lacking in the literature. This study aims to provide benchmark experimental
data for CFD inputs by characterising four different types of commercially
available nasal sprays used in an ENT (Ear Nose Throat) clinic. Spray
characteristics were obtained via high-speed videography, while droplet size
distribution (DSD) measurements were obtained with laser diffraction. Three
actuation forces were evaluated, representing the use-case of an average adult,
average child and the maximum force applied to the spray device. The results
demonstrated that actuation force influenced spray velocity, spray duration,
DSD, and breakup length. Quantitative data of Rosin-Rammler diameter
distributions, spray cone angles, dispersion angles and breakup lengths were
found, assisting computational models with realistic values, thereby improving
future CFD studies of nasal spray drug delivery in the nasal cavity.
