Surface active agents as enhancers of alveolar absorption

Purpose. Small solutes which are deposited in the alveoli by aerosol inhala tion will be absorbed across the alveoli-capillary barrier. Inhalation of d ioctyl sodium sulfosuccinate (DOSS) enhances absorption while having little or no effect on lung function? suggesting that surface active agents may b e used as enhancers of alveolar absorption of inhaled pharmaceuticals. The purpose of this study was to examine the effects of a selection of differen t surface active agents on alveolar absorption. Methods. The absorption of Tc-99m-diethylene triamine pentaacetate (Tc-99m- DTPA) from the lungs was studied in rabbits. We studied five different surf ace active agents: DOSS, sodium glycodioxycholate (GDCA). sodium lauryl sul phate (NaLS), lysophosphatidyl choline (LPC) and polyoxyethylene-23-lauryle ther (P23LE). Results. DOSS and GDCA both dramatically enhanced the absorption of Tc-99m- 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 e xchange or lung compliance. Conclusions. There is a wide spectrum of effects of inhaled surface active agents on the alveolar absorption of Tc-99m-DTPA. Ionic com pounds such as DOSS and GDCA have the greatest effect, and further studies of these classe s of surface active agents for use as enhancers of alveolar absorption of p harmaceuticals seem warranted.