Development of photocrosslinked polyacrylic acid hydrogel as an adhesive for dermatological patches: involvement of formulation factors in physical properties and pharmacological effects.

Photocrosslinked polyacrylic acid hydrogel is a promising candidate adhesive for dermatological patches. In this study, we investigated the effects of the composition and molecular weight of the polymer on the characteristics of the hydrogel. Several photocrosslinkable polymers with different photocrosslinkable moieties or molecular weights were prepared, and various physical properties were measured. Differences in photocrosslinkable modifications markedly affected the swelling behavior of the hydrogel. The molecular weight of the polymer had a significant effect on various physical properties, such as the viscosity of the polymer solution, gel formation, and the swelling behavior of the prepared hydrogels. The pharmacological effects of the hydrogel were also evaluated using carrageenan-induced edema in rats. Application of the hydrogels maintained the skin surface at a reduced temperature throughout the experimental period, and the cooling effect was accompanied by an anti-inflammatory response. Because we can freely control the physical properties of the hydrogel and anticipate the significant pharmacological effects, photocrosslinked polyacrylic acid hydrogel is an attractive candidate adhesive for dermatological patches.