Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI)

Applicability of an exaggerated forearm wash test for efficacy testing of two corticosteroids, tacrolimus and glycerol, in topical formulations against skin irritation induced by two different irritants.

PMID 20923463


Alternatives to corticosteroids in the treatment of irritant contact dermatitis (ICD) are needed and may include glycerol and topical immunomodulators like tacrolimus. Because the efficacy of different treatments in experimentally induced ICD may vary depending on the irritant applied, we tested the efficacy of four anti-irritant compounds using the two different irritants sodium lauryl sulfate (SLS) and nonanoic acid (NON). In a randomized, double-blind, controlled trial, healthy volunteers were exposed to 5% SLS and 50% NON (the right and the left forearm, respectively) in a cumulative wash test. Induction of ICD was obtained by three daily washings for 7 days, followed by a maintenance phase with two daily washings for 12 days. Treatment (triamcinolone acetonide, clobetasol propionate, tacrolimus and glycerol ointment) was started at day 7 and applied immediately after washing. Vehicle and no treatment served as the control. Reactions were evaluated clinically and instrumentally. No treatments were significantly better than the other treatments and controls. There was a tendency toward a dose-dependent response to corticoid treatment, and a trend toward worsened irritancy by tacrolimus on SLS-irritated skin. Explained variance in the experiment by anova revealed a very small effect of treatments compared with an immense and significant subject effect. No claims of effective anti-irritant properties for any of the ointments can be maintained. Application of the present wash test as a tool for anti-irritant efficacy testing may be complicated by the small observed variance explained by treatment.