Development of In Situ Intranasal System Based on Chitosan Formate.

We studied the potential of using a salt form of chitosan as a pH-sensitive in situ matrix. Among common chitosan salts obtained by heterogeneous synthesis, chitosan formate exhibiting the highest pH-sensitivity was selected. However, the low mucoadhesion strength of the composition, as well as high pH required for the phase transition necessitate designing a polycomponent compound with a poloxamer to additionally provide a thermosensitive phase transition. Compared with the use of pure poloxamer, the chitosan complex demonstrated improved mucoadhesion in in vitro studies, and the phase transition parameters were optimal for intranasal administration. An in vivo study revealed no locally irritating effect of the composition, which allows its further development.