In vitro evaluation of surfactants with eucalyptus oil for respiratory distress syndrome

The effects of low doses of eucalyptus oil (EO) were studied on the surface properties of phospholipid suspensions as exogenous surfactants, by in vit ro analysis using a pulsating bubble surfactometer and a Wilhelmy balance. Survanta, ALEC and Exosurf, commonly used surfactants in therapy of respira tory distress syndrome were used as controls for comparison. The test surfa ctants, in Ringer's lactate at 1%, were pulsated at 40 cpm in the surfactom eter. EO caused a significant improvement of adsorption of the surfactants. In the case of the binary mixture of dipalmitoylphosphatidylcholine and ph osphatidylethanolamine (2:3), EO significantly improved the adsorption, sta bility and minimum surface tension obtained. This combination performed bet ter than ALEC and Exosurf and was comparable to Survanta with respect to mi nimum surface tension attained. The re-spreading of a surface excess film o f this mixture in a Wilhelmy balance was higher than that of ALEC and Exosu rf The ultrastructure of the EO enriched surfactants using cryogenic scanni ng electron microscopy showed easy facturability and formation of open memb ranous structures, which could have been associated with the improved surfa ce activity. (C) 2001 Elsevier Science B.V. All rights reserved.