The effects of preservatives on the ciliary beat frequency of chicken embryo tracheas

The effects of preservatives on the ciliary beat frequency of chicken embryo tracheas are determined, Polar compounds like benzalkonium chloride in commonly used concentrations, decrease the frequency less than 30% after a 20 minutes' exposure. The effect is not reversible after rinsing with Locke-Ringer solution. Lipophilic compounds however, like chlorbutol, cause an arrest of the cilary movement with 10 minutes. The effect, different from the polar compounds, is reversible; but only after a limited exposure-time. Mercuric compounds, like thiomersal, decrease the frequency non-reversibly 30 to 90% after a 20 minutes' exposure. EDTA decreases the frequency 40 to 50%, independent of the exposure-time and in a reversible way. The combination of benzalkonium chloride 0.01% and EDTA 0.05% is recommended to preserve nasal drops.