Predicting Percutaneous Absorption of Cosmetic Ingredients Using Artificial Membranes

The skin, which is the largest organ in the human body, protects the body from the external stimuli, as well as plays a role in keeping the external beauty. Because the condition of the skin has a great effect on the quality of life, the safety assessment of beauty care (BC) products, which contact with the skin is important. When the safety assessment is performed, to determine the “the effects of targets on the body”, it is necessary to evaluate “the amount of targets which permeate through the skin in actual usage condition” (skin permeation amount). Although the excised skin tissues from humans or animals with flesh are generally used to evaluate the skin permeation amount, Kao is currently focusing on artificial membranes which mimic the skin tissues. With use of those, multiple samples can be evaluated at the same time, allowing for the understanding of differences in the skin permeation amount depending on each formulation (combination of ingredients) quickly.
On the other hand, it is important to consider the evaporation of water from the formulation applied to the skin when evaluating the skin permeation amount accurately. Using artificial membranes, the permeability parameter “Kp” of the targets can be calculated. However, it is not considered the evaporation of water from the formulation. Therefore, we constructed the new mathematical model incorporating Kp values considered the water evaporation for predicting the skin permeation amount in actual usage condition. As a result, we succeeded to predict the skin permeation amount using not only the new model but also Kp values measured by tests using artificial membranes.
Establishment of new technology which combines the actual test and the theory leads to speed up not only the safety assessment, but also the product development. In the future, we will contribute to the development of safe and secure products by utilizing this technology for screening the better formulations quickly.