The aryl hydrocarbon receptor as the target structure for new drugs in psoriasis and atopic dermatitis

Coal tar therapy was used for centuries to treat skin disorders characterised by inflammation and skin barrier damage. It has been shown that the aryl hydrocarbon receptor (AhR) is the key target structure for these pharmacological effects of coal tar. Since coal tar has been used less and less because of the carcinogenicity of many ingredients of coal tar, other ligands of AhR were studied. Tapinarof is such a ligand and proved to be a promising newdrug to treat psoriasis and atopic dermatitis. Since many endogenous and exogenous ligands of AhR are known, it may be that this tarsmart product is a first example of a new drug family with which dermatologists can treat skin disorders that are characterized by inflammation and skin barrier damage.