Abstract
Five amino acids (L-lysine hydrochloride, glycine, sodium L-glutamate L-proline, and L-threonine) were used in this study. Their percutaneous absorption from pH 7.4 aqueous solution (PBS buffered saline) were investigated on human cadaver skin. The effects of glycerin, sodium PCA etc. on the absorption of L-proline were also investigated. Amino acids did not penetrate into the reservoir within a few hours but the amounts of adsorbed amino acid in stratum corneum were increased when glycerin or sodium PCA was incorporrated. A negative correlation between flux and log P (n-octand/water) was observed when the amino acid penetration into the receiver solution reached steady state. These resulls suggest not only the possibility of micro channels for amino acid permeation into human skin but also the possibility of incorporating amino acids into skin surface to subserve skin function.
