A dynamic random-effects model for recovery of skin barrier function: evaluation of the efficacy of different skin care products

Apparently, the use of mathematical and statistical models to describe the structure and function of the skin barrier is rather limited. The skin barr ier protects the body against uncontrolled loss of water and desiccation, a nd prevents environmental substances from entering the skin. A simple measu re of the barrier function is the transepidermal water loss (TEWL), which i s easy to measure. Healthy skin has low TEWL values, whereas various skin d iseases result in high TEWL values and eventually in the development of dry skin. The use of skin care products can protect and prevent dry skin. In t his study several different trial formulations are compared with respect to their abilities as skin care products. The study is performed as a longitu dinal study on mice, where the skin barrier is broken by means of acetone a nd then treated with one of the formulations. We analysed the data by means of a semimechanistic random-effects model with similarities to pharmacokin etic models. In the model each formulation is characterized by two paramete rs: one that corresponds to the initial barrier restoration effect and one that corresponds to the elimination rate.