ABSTRACT
BACKGROUND: Intranasal corticosteroids (INCS) are a treatment mainstay of chronic rhinosinusitis and allergic rhinitis. Current computational models demonstrate that >90% of INCS drug deposition occurs on the head of the inferior turbinate and nasal valve, rather than the actual sinuses. These models do not consider mucociliary clearance which propels mucus posteriorly, nor do they consider the absorption of the drug. The purpose of this study is to better understand the exact anatomical location where INCS are absorbed. METHODS: Patients with chronic rhinosinusitis and allergic rhinitis taking fluticasone pre-operatively who were scheduled for functional endoscopic sinus surgery and inferior turbinate reduction, respectively, were recruited. Intra-operative tissue samples were obtained from predetermined locations within the sinonasal cavity. Mass spectrometry was then used to quantify the amount of absorption in each specific anatomic location to determine the largest amount of absorption. RESULTS: Eighteen patients were included in our study. The greatest fluticasone absorption levels across the sinonasal anatomy were at the anterior inferior turbinate (5.7 ngl/mL), ethmoid sinus, (4.4 ng/mL), posterior inferior turbinate (3.7 ng/mL), maxillary sinus (1.3 ng/mL), and the sphenoethmoidal recess (0.72 ng/mL) respectively. Absorption was significantly higher in revision surgery compared to surgically naïve patients. CONCLUSIONS: Computation fluid dynamic models of the nasal passage are useful models to help predict intranasal particle flow. However, these models do not incorporate or consider the important mucociliary clearance system, leading to absorption of fluticasone throughout the sinonasal cavity far beyond that predicted by these models. LEVEL OF EVIDENCE: 2 Laryngoscope, 134:1551-1555, 2024.
