The effect of tacrolimus compared with betamethasone valerate on the skin barrier in volunteers with quiescent atopic dermatitis

Summary Background Atopic dermatitis (AD) is an inflammatory skin disease arising as a result of immune system and skin barrier defects. Topical corticosteroids are safe and effective treatments for AD, when used in short courses. Prolonged use is associated with skin barrier damage. Topical calcineurin inhibitors are alternative immune‐modulating treatments for AD purported to have no negative effects on the skin barrier. Objectives To compare the effects of betamethasone valerate 0·1% cream (BMVc) and tacrolimus 0·1% ointment (TACo) on the skin barrier. Methods Twenty volunteers with quiescent AD (no active signs for 6 months) participated in a randomized observer‐blind study, wherein BMVc was applied to one forearm and TACo to the other, twice daily for 4 weeks. The biophysical/biological properties of the stratum corneum were assessed before and after treatment. Nine volunteers with active disease and 10 with healthy skin were assessed at untreated sites. Results BMVc significantly reduced skin barrier function, integrity and cohesion, and the levels of pyrrolidone carboxylic acid (PCA) and urocanic acid (UCA) towards the subclinical barrier defect observed in patients with AD (nonlesional sites). TACo preserved skin barrier function, integrity, cohesion and PCA and UCA levels, while significantly increasing skin hydration to levels comparable with healthy skin. Both treatments reduced skin surface pH and trypsin‐like protease activity, with TACo doing so to a significantly greater degree. Conclusion In quiescent AD, 4 weeks of BMVc treatment adversely affected the biophysical properties of the skin and reduced the levels of natural moisturizing factor, whereas TACo improved the condition of the skin barrier. What's already known about this topic? Skin barrier breakdown is a key event in the development of atopic dermatitis (AD). Prolonged use of potent or moderately potent topical corticosteroids (TCS) disrupts the structure of the skin barrier, thins the stratum corneum (SC) and as a result reduces permeability barrier function. The effect of topical calcineurin inhibitors (TCI) on the skin barrier is still unclear. What does this study add? In subjects with quiescent AD, application of betamethasone valerate reduced skin barrier function, SC integrity and natural moisturizing factor (NMF) levels towards the level of the subclinical barrier defect observed in active disease at nonlesional sites. By comparison, a topical formulation containing tacroli