Cyclodextrins in the production of large porous particles: Development of dry powders for the sustained release of insulin to the lungs

The aim of this work was to develop dry powders intended for insulin pulmonary delivery. To this purpose, large porous particles (LPP) made of poly(lactide-co-glycolide) (PLGA) were produced by the double emulsion-solvent evaporation technique. Hydroxypropyl-β-cyclodextrin (HPβCD), also known as absorption enhancer for pulmonary protein delivery, was tested as aid excipient to optimize the aerodynamic behaviour of the microparticles. Several microsphere formulations, differing in HPβCD and insulin loadings, were produced and their properties compared. A contemporary release of insulin and HPβCD from the system can be achieved by selecting appropriate formulation conditions. HPβCD-containing LPP with flow properties and dimensions suitable for aerosolization and deposition in deep regions of the lung following inhalation were produced. In conclusion, the developed system turns to be of great potential for the combined delivery of the protein and the adsorption promoter in the respiratory tract.