In Vitro Skin Permeation of Hinokitiol Loaded in Vesicles Composed of Behenyltrimethylammonium Chloride and Stearic Acid

The study investigated the use of vesicles composed of behenyltrimethylammonium chloride (BTAC) and stearic acid (SA) for enhancing the skin permeation of hinokitiol (HKL), a compound of interest for hair growth promotion. The vesicles were prepared using a precipitation method. The results showed that no vesicles formed at a molar ratio of BTAC/SA/HKL of 1/1/0, but at ratios of 1/1/0.4, vesicles appeared alongside agglomerates. When the HKL content was further increased to ratios of 1/1/0.8 and 1/1/1.2, exclusively vesicles were observed. In vitro skin permeation studies using hairless mouse skin demonstrated that the flux of HKL through the skin was less than 1 mg/cm2/h when dissolved in alcoholic solutions. However, when HKL was encapsulated in the vesicles, the flux increased to approximately three times higher than that of the alcoholic solutions. The conclusion drawn from the study was that these vesicles could potentially be used to promote hair growth.