Effect of Various Formulation Parameters on the Properties of Hydrogel Wound Dressings

The work presented in this manuscript was undertaken to evaluate the effect of various formulation parameters on the essential properties of hydrogel wound dressings. PVA and PVP based hydrogel dressing systems were prepared by irradiation cross-linking and freeze thawing method. Prepared hydrogels were characterized for swelling index, water vapor transmission rate (WVTR), mechanical strength, gel fraction and in-vitro drug release. Hydrogel dressings prepared by irradiation method showed better physico-mechanical properties like swelling index, WVTR, and transparency as compared to hydrogels prepared by freeze thaw method, except the mechanical strength, which was less in case of hydrogels, prepared using irradiation method. An increase in concentration of PVP resulted in increase in tensile strength and swelling index, and decrease in gel fraction of hydrogel due to higher degree of cross linking. Overall, addition of PVP improves physico-mechanical properties of hydrogel as compared to Plain PVA containing hydrogels. An increase in irradiation dose increases tensile strength, but decreases equilibrium swelling of hydrogels. Gel fraction also increases with increase in irradiation dose up of 50 to 60 kGy, however further increase in irradiation dose decreases gel fraction of hydrogel, as polymer degradation process exceeds cross linking process. Finally, the drug release studies were performed using silver sulfadiazine (AgSD) as a model drug in hydrogel prepared by freeze-thaw method and drug release was found to be zero-order suggesting constant drug availability on the hydrogel applied wound, which is highly desirable.