CFD-Enabled Deep Insert Nasal Delivery for Precision Sinus Targeting

Traditional nasal spray delivery suffers from poor targeting, with most particles depositing in anterior nasal regions, leading to insufficient therapeutic effects, higher dosage requirements, and increased side effect risks. This study quantitatively evaluated nasal spray performance and assessed the benefits of deep versus shallow insertion. A standardized three-dimensional healthy nasal cavity model and computational fluid dynamics were employed, combining the Reynolds-averaged Navier-Stokes k- $\omega$ turbulence model with a two-way coupled discrete phase model. Key spray parameters including injection velocity, cone angle, particle releasing position, injection direction, particle size distribution, insertion depth, and respiratory flow rate, were systematically investigated through 1144 test cases. Target regions were defined based on the clinical importance of the frontal, maxillary, ethmoid, and sphenoid sinus ostia. Deep insertion posterior to the nasal valve markedly enhanced drug transport to sinus targets. Compared with shallow insertion, deep delivery increased total target deposition efficiency from 4.4% to 44.9% and reduced sensitivity to operational errors, with coefficients of variation decreasing by at least 60%. The primary mechanism of improvement was the reduction of ineffective anterior deposition. Deep nasal spray delivery significantly improves drug targeting to the sinuses and enhances robustness against user operational variability. Strategies that increase delivery depth show strong potential to improve therapeutic effectiveness, reduce required dosages, and lower side effect risks for nasal and sinus conditions.