An experimental study of irritant effects of urea in different vehicles

Abstract

The properties ofureaas anirritantwere investigated. Seventeen healthy volunteers were patch tested with 20%ureausing petrolatum and water, respectively, asvehicles.Irritanteffectsofureawere assessed by clinical evaluation of patch test reactions as well as by various non-invasive methods. The inflammatory response was quantified by laser Doppler flowmetry measuring the superficial blood flow, and by ultrasound A-scan reflecting the edema formation. Impairment of the barrier function was indicated by measurement of transepidermal water loss (TEWL). It is concluded that 20%ureain petrolatum applied under occlusion for 24 h elicits significant inflammation (i.e. increase in blood flow and skin thickness) and causes impairment of the skin barrier (i.e. increased TEWL). Theirritantimpact ofureaon the skin depends upon thevehicleused, theirritanteffectbeing intensified whenureais dispensed in petrolatum compared with water.