Establishment of an Evaluation Method to Detect Drug Distribution in Hair Follicles

In the 2018 study, researchers developed a method to assess drug distribution in hair follicles using a cyanoacrylate biopsy (CB) method. They tested this on porcine skin with caffeine (CAF), a hydrophilic drug, and 4-butylresorcinol (BR), a lipophilic drug. The study showed that both drugs were detectable in hair follicles shortly after topical application, with lipophilic BR showing significantly higher amounts than hydrophilic CAF. The CB method produced hair follicle replicas around 175 µm in height, and the recovery ratio of the method decreased with more applications. The findings suggest that the CB method could be useful for evaluating the disposition of topically applied drugs, especially those targeting hair follicles, and could help in establishing an in vitro-in vivo correlation for skin permeation studies. The study was funded by the Hoyu Science Foundation and reported no conflicts of interest.