Abstract

Anise oil, cedar leaf oil and eucalyptus oil were given by steam inhalation to urethane-treated rabbits arranged for the collection of respiratory tract fluid. Cedar leaf oil produced a dose-dependent increase in the volume output and a decrease in the specific gravity of respiratory tract fluid in doses of 1 to 6 mg/kg added to the steam vaporizer, as well as an increase in the content of total solids (mostly soluble mucus) and insoluble mucus. Similar results were obtained by steam inhalation of anise oil and eucalyptus oil but only after administration of large doses, which produced a local inflammatory reaction in the tissues lining the respiratory airway and killed some of the animals. The action of toxic doses was due, at least in part, to inhalation of large volumes of alcohol vapor from the solvent used to dissolve the volatile oils. The results indicate that steam inhalation of cedar leaf oil warrants therapeutic reinvestigation but that addition of anise oil and eucalyptus oil to steam vaporizers adds little but aroma to the therapy.