Release of chlororotetracycline hydrochloride from novel hydrogels based on crosslinked chitosan and PVA

Hydrogels based on hydrochloride polyvinyl alcohol (PVA) containing chlortetracycline and crosslinked chitosan (CS) by glutaraldehyde (GLA) were prepared by the freeze-thawing method and then characterized. The swelling properties and gel fraction of these hydrogels were studied and characterized by FTIR spectroscopy, the thermal and mechanical properties were evaluated by DSC and rheology. Controlled release of chlortetracycline hydrochloride from these hydrogels was studied by UV-Visible spectroscopy. The gel fraction decreases with increase of crosslinked chitosan concentration in hydrogel but the swelling was more important due to the relaxation of the hydrogel, and the extension of macromolecular chains in the system. The crystallinity of these hydrogels increased with increasing PVA concentration. All these hydrogels exhibited a gel character with a high crosslinking degree and possessed a network structure. The release of chlortetracycline hydrochloride from these hydrogels was occurred by fickian diffusion, faster at 37°C than at 25°C because hydrogels were more swollen at 37°C and their network densities were decreased to perfect the release of drugs from hydrogels.