Skin moisturizing effect and skin penetration of ascorbyl palmitate entrapped in solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) incorporated into hydrogel

This study was performed as a complimentary to our previous study regarding the chemical stability of ascorbyl palmitate (AP) in solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC) and for comparison, in nanoemulsion (NE) incorporated into a hydrogel produced by high pressure homogenization. AP is known as an effective antioxidant that protects tissue integrity similar to vitamin C. Recently, its moisturizing activity in conventional topical formulations was found to be high. The aim of the present study was to investigate the moisturizing potential of AP in SLN and NLC incorporated into hydrogel as colloidal carrier systems. It has been known that SLN and NLC have occlusive effects, but AP incorporation moisturized skin significantly better than placebo in short-term (p < 0.001) and long-term trials (p < 0.01) for both SLN and NLC. In the second part of the study, SLN and NLC were found to sustain the penetration of AP through excised human skin about 1/2 and 2/3 times compared to NE (p < 0.001 and p < 0.01), respectively, due to the solid state of Witepsol E85 in the lipid phase.