Effect of topically applied evening primrose oil on epidermal barrier function in atopic dermatitis as a function of vehicle

The aim of this study was to establish the effect on barrier function in atopic dermatitis of topical evening primrose oil in an amphiphilic and a stable water-in-oil emulsion. The studies were vehicle-controlled in two populations of 20 atopic subjects. Barrier function was assessed in terms of transepidermal water loss and stratum corneum hydration after a 4-week treatment period and a 1-week treatment-free period. A barrier function test with sodium lauryl sulphate (SLS) and nicotinic acid ester was also carried out. Evening primrose oil proved to have a stabilising effect on the stratum corneum barrier, but this was apparent only with the water-in-oil emulsion, not the amphiphilic emulsion. The choice of Vehicle is therefore an extremely important factor in the efficacy of topically applied evening primrose oil.