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 nasal decongestant sprays. It has been suggested that BC may be harmful to the nasal mucosa. The present study, involving healthy volunteers, examines effects 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 nasal pool device. Nasal symptoms were determined. Nasal lavage fluid levels of α2‐macroglobulin and fucose were measured as indices of plasma exudation and glandular secretion, respectively. In addition, BC (0.1 mg/mL) was given as single actuations of 100 μL per nasal cavity three times daily for 10 days. The ability of histamine (0.4 mg/mL) to evoke nasal symptoms and plasma exudation responses was determined before and after the repeated BC administration series. Results BC produced immediate nasal smart or pain (P < .05), but tolerance to this response developed by repeated administrations. BC increased nasal mucosal output of fucose (P < .05), whereas nasal lavage fluid levels of α2‐macroglobulin were unaffected. Histamine produced significant symptoms and mucosal exudation of α2‐macroglobulin (P values < .01), equally before and after the 10 days of BC exposure. Conclusions BC in dosages commonly used as preservative in nasal decongestant sprays produced short‐term glandular secretion and nasal smart or pain. However, 10 days' frequent exposure to BC was not associated with untoward symptomatic effects, nor was a sensitive mucosal variable such as histamine‐induced exudative responsiveness affected by this repeated exposure to BC.