Effects of benzalkonium chloride on innate immunity physiology of the human nasal mucosa in vivo

Objective: Benzalkonium chloride (BC) is a preservative commonly used in na sal decongestant sprays. It has been suggested that BC may be harmful to th e nasal mucosa. The present study, involving healthy volunteers, examines e ffects of BC on nasal mucosal end-organ functions. Methods: Isotonic saline and BC (0.1 mg/mL) were administered acutely to the nasal mucosa using a n asal pool device. Nasal symptoms were determined, Nasal lavage fluid levels of alpha(2)-macroglobulin and fucose were measured as indices of plasma ex udation and glandular secretion, respectively. In addition, BC (0.1 mg/mL) was given as single actuations of 100 mu L per nasal cavity three times dai ly for 10 days. The ability of histamine (0.4 mg/mL) to evoke nasal symptom s and plasma exudation responses was determined before and after the repeat ed BC administration series. Results: BC produced immediate nasal smart or pain (P < .05), but tolerance to this response developed by repeated admini strations. BC increased nasal mucosal output of fucose (P < .05), whereas n asal lavage fluid levels of alpha(2)-macroglobulin were unaffected. Histami ne produced significant symptoms and mucosal exudation of alpha(2)-macroglo bulin (P values < .01), equally before and after the 10 days of BC exposure . Conclusions: BC in dosages commonly used as preservative in nasal deconge stant sprays produced short-term glandular secretion and nasal smart or pai n. However, 10 days' frequent exposure to BC was not associated with untowa rd symptomatic effects, nor was a sensitive mucosal variable such as histam ine-induced exudative responsiveness affected by this repeated exposure to BC.