Microencapsulated chitosan nanoparticles for pulmonary protein delivery: in vivo evaluation of insulin-loaded formulations.

This work presents a new dry powder system consisting of microencapsulated protein-loaded chitosan nanoparticles (CS NPs). The developed system was evaluated in vivo in rats in order to investigate its potential to transport insulin (INS), a model protein, to the deep lung, where it is absorbed into systemic circulation. The INS-loaded CS NPs were prepared by ionotropic gelation and characterized for morphology, size, zeta potential, association efficiency and loading capacity. Afterwards, the NPs were co-spray dried with mannitol resulting in a dry powder with adequate aerodynamic properties for deposition in deep lungs. The assessment of the plasmatic glucose levels following intratracheal administration to rats revealed that the microencapsulated INS-loaded CS NPs induced a more pronounced and prolonged hypoglycemic effect compared to the controls. Accordingly, the developed system constitutes a promising alternative to systemically deliver therapeutic macromolecules to the lungs, but it can also be used to provide a local effect.