Mechanics-guided parametric modeling of intranasal spray devices and formulations for targeted drug delivery to the nasopharynx.

Introduction: Improving the efficacy of nasal sprays by enhancing targeted drug delivery to intra-airway tissue sites prone to infection onset is hypothesized to be achievable through an optimization of key device and formulation parameters, such as the sprayed droplet sizes, the spray cone angle, and the formulation density. This study focuses on the nasopharynx, a primary locus of early viral entry, as the optimal target for intranasal drug delivery. Methods: Two full-scale three-dimensional anatomical upper airway geometries reconstructed from high-resolution computed tomography scans were used to numerically evaluate a cone injection approach, with inert particles mimicking the motion of sprayed droplets within an underlying inhaled airflow field of 15 L/min, commensurate with relaxed breathing conditions. Therein we have considered monodisperse sprayed particles sized between 10-50 Results: The resulting three-dimensional deposition contour map, obtained by interpolating the outcomes for the discrete test parameters, revealed that the mean nasopharyngeal deposition rate peaked for particle sizes Discussion: The overall findings, while implicitly tied to the two test subjects (i.e., for spray administration through four representative nasal pathways), do collectively demonstrate that rational optimization of the intranasal sprays for targeted nasopharyngeal deposition is attainable with actionable design modifications on the sprayed droplet sizes and device plume angles.