Hydrogels of natural origin in wound healing : formulation devolopment

Abstract

Hydrogels made of chitosan has a well-established place in drug delivery for the skin. Our particular interest were hydrogels for wound healing. Hydrogels from low, medium and high molecular weight were prepared in different concentrations for texture and release characterization incorporating liposomes and chloramphenicol as a model drug. A method for comparing viscosity between gels was established with a Texture analyser and back-extrusion method. The method proved to be able to distinguish differences between gels with standard deviations varying with less than 2%. Different liposomal chitosan hydrogels were prepared with or release studies with the model drug chloramphenicol. The release study proved that liposomal hydrogels could act as vehicles for antibiotics in depot formulations. Chitosan preparations were also tested under both accelerated stability testing and freeze-thaw test. Stability was improved with glycerine in the hydrogels. Stability seemed to be dependant on molecular weight and concentration of chitosan. The low molecular weight chitosan gels were the least stable, and higher concentrations can give more stable gels.