Background: Benzalkonium chloride (BKC) has been considered an innocuous preservative for prescription drugs.
Methods: We performed a double-blind, placebo-controlled, randomized, crossover, single-center trial with a 3-week washout period in 43 healthy volunteers comparing the effect of 3-week use of saline nasal spray containing BKC 0.01% to preservative-free saline t.i.d. on nasal mucociliary clearance rate. Evaluations were done at the beginning and the end of each period by gamma-scintigraphy with technetium99m-labeled strontium.
Results: Nasal mucociliary clearance rate was significantly impaired by BKC with a difference of 1.23 mm x min(-1) (p < 0.01) between periods.
Conclusion: BKC in the concentration used in nasal preparations impaired mucociliary clearance in healthy individuals after 3 weeks of use. Presently, when preservative-free alternatives are available, BKC could be a risk without benefit.