Development and characterization of in situ gel system for nasal insulin delivery

The objective of the present study was to develop a thermosensitive in situ gel system based on chitosan and poly vinyl alcohol (PVA) for nasal delivery of insulin. The hydrogel was prepared by mixing chitosan and PVA. The concentration of the components was optimized during formulation development. The prepared hydrogel was characterized for gelation temperature, gelation time, viscosity changes, degree of swelling, in vitro release and in vivo hypoglycemic effect. The prepared hydrogel was liquid at room temperature while underwent thermal transition from solution below or at room temperature to non-flowing hydrogel when incubated at 37 degrees C for approximately 12 minutes with increased viscosity. The in vitro release of insulin from gel network was observed spectrophotometrically which was good enough to maintain blood glucose level for six hour. Furthermore, the formulation when evaluated for their in vivo hypoglycemic effect, demonstrated its ability to reduce glucose level. The observed in vitro and in vivo results indicate that the proposed thermosensitive in situ gelling system has substantial potential as nasal delivery system for insulin.