Preparation and characterization of salmon calcitonin loaded chitosan nanopaticles dry powder for pulmonary delivery

Abstract

Even though salmon calcitonin (sCT) has been known as a potent hypocalcemic agent, only injection or nasal spray products are available on the market and it has limitations of using. This study aims to encapsulate sCT into chitosan-based nanoparticles using a ionic gelation method and to fabricate them as inhalable powder using spray drying technique. The optimal chitosan/TPP nanoparticles were prapared and the effect of different chitosan concentrations and ratios of chitosan:tripolyphosphate (CS/TPP) on the formation and physicochemical properties of nanoparticles were investigated. The resultant sCT loaded chitosan nanoparticles were in the mean size of 153 to 240 nm and exhibited positive zeta potential from +32.7 to +41.2 mV. The highest association efficiency of sCT into chitosan nanoparticles was found to be about 63% at 3:1 ratio of chitosan:TPP, prepared with 0.1% chitosan concentration. The study indicated that the concentration of either chitosan and CS/TPP ratio affected to nanoparticles size. Nanoparticles were characterized for morphology by TEM images and conformational changes were detected by CD and FTIR, it show a slightly effect of preparation process to sCT conformation. Microparticles were prepared by co-spray drying of 3:1 CS/TPP nanoparticles with 70, 80 and 90% of lactose and mannitol, with respect to nanoparticle weights and excipient concentration, as well as spray drying conditions, were investigated. In vitro inhalation parameters including fine particle fraction (FPF) and emitted dose percentage (ED%) were measured by the Andersen cascade impactor (ACI). The in vitro deposition data indicated that processing of nanoparticles with mannitol improved the aerosolization properties of sCT loaded CS-NPs dry powder significantly. 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 sCT levels following intratracheal administration to rats revealed that the microencapsulated sCT-loaded CS NPs induced a more pronounced and promote peptide absorption compared to the controls. Accordingly, the developed system constitutes a promising alternative to systemically deliver therapeutic macromolecules to the lungs.