Surface active agents as enhancers of alveolar absorption.

Abstract

Small solutes which are deposited in the alveoli by aerosol inhalation will be absorbed across the alveolo-capillary barrier. Inhalation of dioctyl sodium sulfosuccinate (DOSS) enhances absorption while having little or no effect on lung function, suggesting that surface active agents may be used as enhancers of alveolar absorption of inhaled pharmaceuticals. The purpose of this study was to examine the effects of a selection of different surface active agents on alveolar absorption. The absorption of 99mTc-diethylene triamine pentaacetate (99mTc-DTPA) from the lungs was studied in rabbits. We studied five different surface active agents: DOSS, sodium glycodioxycholate (GDCA), sodium lauryl sulphate (NaLS), lysophosphatidyl choline (LPC) and polyoxyethylene-23-laurylether (P23LE). DOSS and GDCA both dramatically enhanced the absorption of 99mTc-DTPA. There was a moderate effect of NaLS, no significant effect of LPC and P23LE reduced the rate of absorption. None of the compounds affected gas exchange or lung compliance. There is a wide spectrum of effects of inhaled surface active agents on the alveolar absorption of 99mTc-DTPA. Ionic compounds such as DOSS and GDCA have the greatest effect, and further studies of these classes of surface active agents for use as enhancers of alveolar absorption of pharmaceuticals seem warranted.