Aerosolized liposomes with dipalmitoyl phosphatidylcholine enhance pulmonary insulin delivery

The pulmonary insulin delivery characteristics of liposomes were examined. Aerosolized liposomes containing insulin were administered into rat lungs and the enhancing effect on insulin delivery was evaluated by changes of plasma glucose levels. Liposomes with dipalmitoyl phosphatidylcholine (DPPC) enhanced pulmonary insulin delivery in rats, however, liposomes with dilauroyl, dimyristoyl, distearoyl or dioleoyl phosphatidylcholine did not. Liposomes with DPPC also enhanced the in vitro permeation of FITC dextran (Mw 4400, FD-4) through the calu-3 cell monolayer by reducing the transepithelial electrical resistance and did not harm lung tissues in rats. These findings suggest that liposomes with DPPC enhance pulmonary insulin delivery by opening the epithelial cell space in the pulmonary mucosa not mucosal cell damage. Liposomes with DPPC could be useful as a pulmonary delivery system for peptide and protein drugs.

Aerosolized liposomes with dipalmitoyl phosphatidylcholine (DPPC) enhanced pulmonary insulin delivery and decreased plasma glucose level in rats although liposomes with other phospholipids have no effects.A) PBS (○); insulin solution (●); liposomes with EPC (△), DLPC (▲), DMPC (□), DPPC (■), DSPC (◇) or DOPC (◆) containing insulin.B) D% values are indexes of the enhancing effect on pulmonary insulin absorption.Figure optionsDownload as PowerPoint slide