The effect of nasal patency on the clearance of radiolabeled saline in healthy volunteers

Purpose. The objective of this study was to investigate the effect of nasal cavity patency on the penetration, deposition, and clearance of an aqueous isotonic saline solution. Methods. The study was carried out as a single center, open, randomized, 2- way cross-over in healthy volunteers. Nasal patency was assessed using mist ing patterns on a cold metal surface at the beginning and end of study. 100 mu l of technetium-99m radiolabeled saline solution was introduced into ei ther the most or least patent nasal cavity using a purpose designed spray d evice. The distribution and residence time of the radiolabel was followed f or 2 hours using gamma scintigraphy. Results. The mean times to 50% clearance were 34 +/- 7 and 28 +/- 12 minute s (+/-s.d.) for the side view of the least and most patent nasal cavity res pectively. Total clearance of the radiolabelled saline from the nose was tr ot affected by patency. Between 7 and 35% of the radiolabelled saline solut ion remained in the nasal cavity at the end of imaging. Using endoscopy to track the clearance of an aqueous solution of food dye using the same deliv ery procedure, identified this region as hair in the nasal vestibule. The d ye was seen to dry in this region along with the mucus. Conclusions. Nasal patency affects the initial, but not total clearance of solutions, however, the remaining solution may not be available for drug de livery.