The effect of some preservatives used in nasal preparations on mucociliary clearance.

The effect of methyl-p-hydroxybenzoate, propyl-p-hydroxybenzoate, chlorbutol, chlorocresol, EDTA, benzalkonium chloride, chlorhexidine, phenylmercuric nitrate and phenylmercuric borate on mucociliary transport rate of the frog palate has been examined. Following a variable number of applications all these preservatives halted transport, the first three reversibly. However, applications of thiomersal (0.01%) were well tolerated. The frog palate possesses a ciliated epithelium protected by mucus, since some of our findings are at variance with those previously reported results where the protective effect of mucus was negligible in the in-vitro model (usually trachea) employed, it would appear that the contribution of mucus to effective mucociliary clearance should not be underestimated.