EVALUATION OF SKIN IRRITATION OF PERCUTANEOUS-ABSORPTION PROMOTERS BYMEANS OF FRACTAL DIMENSION OF RAT SKIN-STRUCTURE

A fractal dimension of skin structure was determined in order to evalu ate tl-e pathological damages evoked by percutaneous absorption promot ers such as d-limonene and Atone in the hairless rat. As a model derma tological system, indomethacin hydrogels containing each of these enha ncers were applied to the hairless rat abdominal skin. The application site of the skin was excised, fixed with glutaraldehyde and osmic aci d, and then lyophilized. Boundary lines between the outermost lipid la yer and the underlying protein parts in the skin cross section were ta ken by the CCD camera as image data, and these images were fed into a computer to estimate the fractal dimension. The boundary line of the s kin cross section was observed to be a typical fractal morphology and the structure changes of skin evoked by the promoters could be quantif ied as a non-integral fractal dimension. A linear relationship between the fractal dimension and pathological irritation score was clearly o bserved, suggesting the usefulness and reliability of the fractal dime nsion as a novel method for evaluating the skin damage.