Nitrosalicyl-imine-chitosan hydrogels based drug delivery systems for long term sustained release in local therapy.

The paper focuses on the synthesis and characterization of new drug delivery systems for local therapy. They were prepared by in situ hydrogelation of chitosan biopolymer with nitrosalicylaldehyde in the presence of a model drug, varying the crosslinking density. The structural, supramolecular and morphological characteristics of the systems were studied by FTIR spectroscopy, X-ray diffraction and, POM and SEM microscopy. In vitro release of the drug has been explored in simulated physiological conditions and in vivo release was investigated by the somatic pain model on rats. Information on the biodegradation of the systems was gain by simulating experiments of enzymatic degradation. The systems were biodegradable and showed a prolonged drug release, assuring an in vivo efficient therapeutic effect over 5 days, with no systemic toxicity. All these findings demonstrated that the new hydrogels based on nitrosalicyl-imine-chitosan provides a practical approach for sustained drug delivery for local chemotherapy.