SKIN PENETRATION PROPERTIES ! 5 3 1,6 1,2 0,4 0,0 1st 2rid 3rd 4th 5th 6th 7th 8th 9th loth Tape strip -•- untreated --•-w/o cream (1 h) --•-w/o cream ($ h) Figure I. Kinetics of vitamin E penetration (pg/cm 2 tape strip) from a w/o cream into the stratum corneum after exposure periods of one hour and five hours (SEM for n = 4). cream (12--14). These lameliar layers impede the free diffusion of vitamin E from the oil phase into the skin (10,15). There are no differences in the oil components and vitamin contents between both emulsion types and only small differences in emulsifiers. There- fore, the differences observed in the penetration properties are attributed mainly to the 1,2 0,8 0,4 0,0 1st 2nd 3rd 4th 5th 6th 7th 8th 9th loth Tape strip -e-untreated -x- o/w cream (1 h) -•- o/w cream ($ h)l Figure 2. Kinetics of vitamin E penetration (pg/cm 2 tape strip) from a lameilar o/w cream into the stratum corneum after exposure periods of one hour and five hours (SEM for n = 4).

154 JOURNAL OF COSMETIC SCIENCE 5,0 •4,0 3,0 1,0 0,0 1st 2nd 3rd 4th 5th 6th 7th 8th 9th loth Tape strip --•-w/o cream (1 h) --*-w/o cream (5 h)] Figure 3. Kinetics of D-panthenol penetration (tig/cm 2 tape strip) from a w/o cream into the stratum corneum after exposure periods of one hour and five hours (SEM for n = 4). different phase and viscosity behavior of the emulsions in the course of drying on the skin. After passing the stratum corneum, which represents the actual penetration barrier, the vitamins enter into deeper skin layers. Therefore, for vitamin E not only adhesive tape 1,0 .......... , 0,0 1st 2nd 3rd 4th 5th 6th 7th 8th 9th loth Tape strip -•-o/w cream (1 h) -*-o/w cream (5 h)l Figure 4. Kinetics of D-panthenol penetration (pg/cm 2 tape strip) from a lameliar o/w cream into the stratum corneurn after exposure periods of one hour and five hours (SEM for n = 4).