Abstract
Stratum corneum which is the uppermost layer of skin acts as its barrier. Therefore, scarcely any kind of drug can be delivered into and through skin. In order to settle this problem, many agents and technology have been developed, for example transdermal absorption enhancers. In the field of cosmetics, high performance products containing moisturizers, or whitening agents have recently been developed. Regarding these products, the penetration of these cosmetic ingredients into skin have become of major importance for cosmetic developer. However, most of absorption enhancers cannot be utilized for cosmetics because of their tendency to cause skin roughness. We need a way in which no-irritation for skin is caused and therefore can be practically used for cosmetics. The purpose of this study is to increase accumulative quantity of cosmetic ingredients into stratum corneum/epidermis utilizing on for absorption carrier. Yucatan micropig (YMP) skin is used for this examination for it resembles the human skin histologically. dl-α-Tocopheryl nicotinate and butyl parahydroxybenzoate are used for oil soluble agents. From our experiments, we found that the oils which increase accumulative quantity of oil soluble agents were divided into two groups. The oils we call group A have high solubility parameter. The solubility parameter of these oils was in correlation with their accumulative quantity of the oil soluble agents. Another group of oils, group B, have specific solubility parameter from 16.0 to 17.5. The affinity of stratum corneum's keratin protein and these two groups of oils were investigated utilizing three dimensional solubility parameter.
