Comparison between TEWL and laser scanning microscopy measurements for the in vivo characterization of the human epidermal barrier.

The analysis of the skin barrier properties is important in various fields of medical treatment and cosmetology. The development and improvement of topically applied substances require an objective analysis of the skin barrier characteristics. Transepidermal water loss (TEWL) measurement is the standard method to characterize epidermal barrier function. The most important disadvantage of this method though, is that it can be affected by different exogenous and endogenous factors, e.g. water content of the applied formulation and room temperature. In the present study, TEWL measurements are compared to laser scanning microscopic (LSM) measurements, concerning the use of these two methods for the non-invasive in vivo characterization of the epidermal barrier function. The investigations were performed prior and subsequent to treatment of dry skin with a gel mixture, developed for skin treatment after radiotherapy for cancer. The present results indicate that in vivo laser scanning microscopy is an appropriate method for the characterization of the skin barrier structure without interference by external factors.

Clobetasol propionate--where, when, why?

Clobetasol propionate is the most potent of all topical steroids. It is successfully applied in the treatment of various skin diseases such as atopic dermatitis, psoriasis and vulvar lichen sclerosus. The therapy is, however, mainly symptomatic. A preventive effect is only reported in the treatment of the latter. Clobetasol propionate exerts antiinflammatory, immunosuppressive and antimitotic effects influencing the growth, differentiation and function of various cells and inhibiting cytokine production. Seven different dosage forms are available to deliver the drug to the living cells of the skin. Their choice might additionally affect patient compliance. The potency of clobetasol propionate, however, is accompanied by local and systemic side effects, such as skin atrophy and hypothalamic-pituitary-adrenal axis suppression. Patients applying clobetasol propionate must be well instructed in how to use it. Physicians prescribing clobetasol propionate should consider a diversity of factors and be able to answer the questions where, when and why.