Optimizing topical delivery to the ostiomeatal complex after functional endoscopic sinus surgery using a bidirectional delivery method

Chronic rhinosinusitis with nasal polyps (CRSwNP) remains a therapeutic challenge due to frequent recurrence after surgery, largely stemming from inadequate drug delivery to the posterior nasal mucosa, particularly the ostiomeatal complex (OMC). While aerosol dynamics are known to influence intranasal drug deposition, quantitatively assessing deposition patterns within complex nasal anatomies is difficult. This study employed a bidirectional delivery approach using computational fluid dynamics (CFD) simulations based on patient-specific sinonasal cavity models, incorporating realistic polydisperse particle size distributions. The effects of device nosepiece insertion angle, nosepiece wall thickness, and exhalation flow rate on drug delivery efficiency were systematically analyzed. Simulated results were validated against in vitro experiments using 3D-printed nasal cavity replicas. Findings revealed that lateral adjustment of the nosepiece insertion angle significantly enhanced drug deposition in the OMC region, while variations in wall thickness and exhalation flow rate had comparatively modest effects. Particles ≤ 15.5 μm and ≥52.5 μm showed greater OMC deposition than mid-sized particles, with exhalation flow rate positively correlated with total OMC mass deposition within the 15–45 L/min range. These results highlight the dominant role of nosepiece insertion orientation in optimizing regional delivery and the nuanced effects of particle size and flow dynamics. This study offers a comprehensive framework for evaluating nasal drug delivery performance based on realistic device parameters and particle behavior, providing actionable insights to guide the design of more effective nasal delivery systems for treating CRSwNP.