Tokuoka Yoshikazu, Suzuki Megumi, Ohsawa Yumiko, Ochiai Akira, Ishizuka Masahiro, Kawashima Norimichi
Faculty of Biomedical Engineering, Toin University of Yokohama, Aoba-ku, Yokohama, Japan.
Drug Dev Ind Pharm. 2008 Jun;34(6):595-601. doi: 10.1080/03639040701831850.
Enhancing effect of l-menthol and its derivatives, l-menthyl formate, l-menthyl acetate, and l-menthyl propionate, on skin permeation of 5-aminolevulinic acid (ALA) through Yucatan micropig full-thickness skin was investigated using a Franz-type diffusion cell. ALA solutions were prepared using ethanol-water mixed solvents with l-menthol or the derivative. Skin permeation coefficients (Kp) of ALA with more than 3.0 wt% of l-menthol was significantly larger than that without l-menthol. In addition, Kp of ALA with the derivative increased as follows: l-menthol approximately l-menthyl propionate < l-menthyl formate < l-menthyl acetate. These results suggest that l-menthol and the derivative are effective to enhance ALA skin permeation.
