An investigation and characterization on alginate hydogel dressing loaded with metronidazole prepared by combined inotropic gelation and freeze-thawing cycles for controlled release.

The purpose of this study was to investigate the effect of combined Ca(2+) cross-linking and freeze-thawing cycle method on metronidazole (model drug) drug release and prepare a wound film dressing with improved swelling property. The hydrogel films were prepared with sodium alginate (SA) using the freeze-thawing method alone or in combination with ionotropic gelation with CaCl2. The gel properties such as morphology, swelling, film thickness, and content uniformity and in vitro dissolution profiles using Franz diffusion cell were investigated. The cross-linking process was confirmed by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. In vitro protein adsorption test, in vivo wound-healing test, and histopathology were also performed. The hydrogel (F2) composed of 6% sodium alginate and 1% metronidazole prepared by combined Ca(2+) cross-linking and freeze-thawing cycles showed good swelling. This will help to provide moist environment at the wound site. With the in vivo wound-healing and histological studies, F2 was found to improve the wound-healing effect compared with the hydrogel without the drug, and the conventional product.