New formulations based on salicyl-imine-chitosan hydrogels for prolonged drug release.

The objective of this paper was to investigate the new formulations based on salicyl-imine-chitosan hydrogels as potential controlled drug release systems. They were prepared by in situ hydrogelation of chitosan with salicylaldehyde in the presence of diclofenac sodium salt (DCF) as model drug. FTIR, X-ray Spectroscopy, POM and SEM techniques were used to confirm the structural, supramolecular and morphological particularities of the formulations. Swelling test, in vitro enzymatic biodegradation and release profile were investigated in similar conditions mimicking the in vivo environment, and the release mechanism was assessed by fitting into five mathematical models. It was established that the formulations have the capacity to release DCF in a sustained manner for 10 days rate, the drug release rate being correlated to the crosslinking density and hydrogelation speed. The biodegradation occurred in three main stages, reaching a mass loss of 48% after 21 days. In order to be used in the biomedical field, the in vivo biocompatibility of the formulations was investigated on experimental rats. After 7 days of subcutaneous implantation, no influence on the hematologic profile, liver, kidney or immune defence capacity were observed, suggesting these formulations as valuable materials for biomedical devices.