Enhanced pulmonary delivery of insulin by lung lavage fluid and phospholipids

Pulmonary delivery appears to be the most promising non-parenteral route of insulin administration. In this work, we investigated the enhancement of i nsulin absorption in the presence of phospholipids and lung lavage fluid in vivo and in vitro. In-vitro experiments of insulin uptake by type II cells showed a significantly enhanced absorption in presence of lavage fluid, co mpared to Various buffer preparations. The same trend was obtained with in- vivo studies of tracheal instillation of insulin. The incorporation of phos pholipids as absorption enhancers in 1,2-dipalmitoyl phosphatidylcholine (D PPC) dispersion was compared to blank liposomes. A significantly higher blo od glucose decrease was observed with a DPPC-insulin physical mixture compa red to liposome, suggesting a possible effect of the phospholipid chain phy sical state on the insulin in-vivo absorption. (C) 2001 Elsevier Science B. V. All rights reserved.