Analysis of the Pretreatment Effect of Ethanol on the Stratum Corneum and Hair Follicular Penetration of Drugs Using the Hair Follicle Plugging Method

The study investigated the impact of ethanol (EtOH) pretreatment on drug penetration through the skin and hair follicles using the hair follicle-plugging method. In vitro experiments with excised pig ear skin and four model drugs showed that hair follicle-plugging reduced the skin permeation of ionized lidocaine (LC), fluorescein (FL), and fluorescein isothiocyanate (FITC)-dextran 4 kDa (FD-4). Specifically, hair follicle-plugging prevented the permeation of FL and FD-4 in EtOH-pretreated skin but did not affect isosorbide mononitrate (ISMN). The effect on ionized LC varied with different pretreatment conditions. The findings suggested that EtOH pretreatment significantly influenced the aqueous pathways in the stratum corneum and hair follicles.