In this study, topically applicable o/w microemulsion (ME), o/w simple emulsion (SE) and solid lipid nanoparticle (SLN) cosmetic delivery systems were prepared containing vitamin E. Characterization of the systems was performed by various techniques, particle size and zeta potential measurement, X-ray diffraction, NMR, vitamin E quantification by validated HPLC method. Release properties of vitamin E from the formulations were determined in vitro using Franz diffusion cells with a synthetic membrane (0.22 fim). Antioxidant effects of the formulations prepared were investigated in vitro by 2,2-diphenyl-1-picrylhydrazyl (DPPH) test. Antioxidant efficacy was also tested in vivo by measuring net skin elasticity and skin roughness values. Vitamin E could be incorporated successfully into ME, SE and SLN delivery systems. The best long-term physical stability was obtained for the microemulsion system. As a result of skin efficacy tests, it can be concluded that SLN formulation containing vitamin E improves skin moisture while decreasing skin roughness (p≤ 0.01) indicating an antiaging efficacy. ME and SE formulations were also found to decrease skin roughness (p≤ 0.001).

Keywords: Vitamin E, Microemulsion, Emulsion, Solid lipid nanoparticle, In vivo evaluation on skin