124 JOURNAL OF COSMETIC SCIENCE 0.3 0.2 0.1 o 250 1.5 A ............... Ocean Optics Cary 5G i i 300 350 400 • Roviparts © B x5 • 1- • 0.5- i•'.....-_ ....... lameliar cream '• ........... Rovisome 0- i i 250 300 350 400 5 )• Rovisome C 4- / •/•0% Vitamin E acetate • / ~ ,,' • Vitamin E acetate c 3 • / /" '"'i • •ovipa"s © ./'""- "'• '"..• ] + 10 % Vitamin E acetate ,•, '""% ...................................................?ill ..... i I 250 300 350 400 wavelength [nm] Figure 2. (A) Spectra of adhesive tapes measured by a minispectrometer (Ocean Optics) and a Cary 5G double monochromator spectrometer (the upper two spectra are offset for clarity). (B) Formulation com- ponents, (C) Rovisome ©- and Roviparts©-containinF= vitamin E acetate and pure vitamin E acetate.

VITAMIN E ACETATE PENETRATION STUDIES 125 0.20 0.15 0.10 calculated spe•tru"•"'-'- --- •_.... (offset) baseline-component '-'•--•--._.. comeocytes • •••v•amin E acetate 2(i0 280 300 320 340 3130 wavelength [nm] Figure 3. Component spectra, measured spectrum of a tape loaded with corneocytes and vitamin E acetate, and a calculated spectrum as a result from a spectral least-squares fit. RESULTS ACTIVATION/IRRITATION POTENTIAL The irritation assay using whole skin biopsies differentiates biochemically between the cytotoxic and irritant potential of substances applied to the skin surface. Using both parameters, the reversible (activation/irritancy) and the non-reversible (cytotoxicity) parts of the irritation potential of test material, depending on the skin barrier function, can be characterized (1 1). With lapses of 60 minutes after starting the application and 30 minutes after finishing the application, different results were observed with regard to the cytotoxic and irritant potential of the three types of emulsion in comparison to the untreated area, as shown in Figure 4. No major differences between the three emulsions (LC, RP, and RS) were manifested by the cytotoxicity assay (MTT). Generally, a negative deviation between 6% and 7% from the untreated control sites was found, which was within the biological variation. The results for the untreated site are characterized by normalized mean and standard deviation (100% + 5%). Compared to the untreated controls, the increase of the PGE 2 tissue concentration (activation/irritancy) induced by the LC using Rovisome © (RS) as liposomal carrier was higher (119% + 8%) than the concentration induced by the other emulsions (RP: 110% + 3% LC: 105% + 2%). ADHESIVE TAPE STRIP ANALYSIS: RESULTS OF THE HPLC METHOD The first set of 15 successively taken adhesive tape strips was analyzed by a conventional HPLC method, and the analytical results were calculated as pg/cm 2 per tape strip. This