THE EFFECTS OF TOPICAL NASAL STEROIDS ON RAT RESPIRATORY MUCOSA IN-VIVO, WITH SPECIAL REFERENCE TO BENZALKONIUM CHLORIDE

Fifty rats were treated with topical nasal steroids with and without t he preservative benzalkonium chloride in their right nostril twice dai ly for 21 days, while the left nostrils were exposed to 0.9% NaCl. By cutting the noses serially in frontal sections, the structure of the m ucosal lining of all parts of the nose could be investigated. Areas wi th squamous cell metaplasia were observed in sill nostrils exposed to topical steroids containing benzalkonium chloride. Such alterations we re not observed in any nasal cavities exposed to the topical nasal ste roid without the preservative or to 0.9% NaCl. In conclusion, benzalko nium chloride appears to be potentially toxic to the mucosa in vivo.