Evaluation of surfactant-like effects of commonly used remedies for colds.

Volatile aromatics, eucalyptol, eucalyptus oil, camphor and menthol were spread on synthetic DPL films and pulmonary surfactants; the initial surface pressure of the surfactants was measured and the additional surface pressure increment recorded. Eucalyptol was allowed to be inhaled by rabbits and lung compliance was monitored. Under our experimental conditions the volatile aromatics exhibited surfactant-like effects, namely a decrease in surface tension between water and air and thus improved lung compliance values in vivo.