The effects of oxymetazoline on lysozyme secretion from the human nasal mucosa

Lysozyme is a protein secreted by nasal submucosal glands. Its secretion is under cholinergic control. It is considered important in nasal defence as it enzymatically hydrolyses peptidoglycan bonds in bacterial cell walls and has specific activity against Gram-positive bacteria in vitro. Oxymetazoline is freely available as a non-prescription nasal decongestant. Some recent work has shown that it has no effect on histamine-induced plasma exudation but little is known about its effects on glandular secretion. The current study is a randomized controlled study that investigates the effect of topical oxymetazoline on the total protein and lysozyme content of nasal fluid. Thirty healthy volunteers were randomized to receive either a normal saline nasal spray (placebo) or an active spray of oxymetazoline, 0.05% (w/v) in saline. NAR was assessed in all subjects using posterior rhinomanometry and nasal lavage before the application of the spray and again 10 min later. The results were analysed using non-parametric statistics. There was a significant decrease in both the lysozyme and total protein content of nasal lavage after application of oxymetazoline when compared with placebo (p < 0.05). A possible mechanism for the observed decease in total protein and lysozyme would be that the vasoconstrictor effects of oxymetazoline also apply to the vessels supplying nasal submucosal glands and that this decrease in blood supply is reflected by a decrease in secretion.