Percutaneous absorption test – A case of effectiveness evaluation of skin-whitening cosmetics

To evaluate the effect of skin-whitening cosmetics, there is currently available a method to evaluate the degree of the disappearance of pigmented areas produced by ultraviolet irradiation by applying a sample to the skin. This method is convenient for evaluating a cosmetic formula. In animal models, this method shows much less individual differences, and due to the easiness in preparing animals to be tested, it is easier to obtain the number of experiments necessary for statistical analysis, providing an advantage in making an objective evaluation. However, fixing a live animal for irradiating with ultraviolet rays etc. may cause pain to the animal. By adopting an alternative method, we believe that "reduction in pain for testing animals" will become possible. In evaluating the effectiveness of a skin-whitening cosmetic, we produced a Percutaneous Absorption Test, in addition to the blackening reduction test in humans. This enabled us to predict the difference in the skin-whitening effect of a formula more clearly. This case proved the effectiveness of a formula of a skin-whitening cosmetic without use of a testing animal, and we described the evaluation of the