EFFECTS OF CALCIPOTRIOL ON STRATUM-CORNEUM BARRIER FUNCTION, HYDRATION AND CELL RENEWAL IN HUMANS

Calcipotriol, a vitamin D analogue utilized for psoriasis, has irritat ion as its most frequent reported adverse event, However, studies on i ts irritant properties in humans have produced conflicting data, This study evaluates the effect of calcipotriol on stratum corneum barrier function, hydration and cell turnover in healthy volunteers, compared with sodium lauryl sulphate (SLS) as a model irritant, Calcipotriol 0. 005% ointment and 1% aqueous SLS solution were applied for 60 min once daily for 2 weeks (5 consecutive days weekly) on untreated and on dan syl-chloride-labelled skin. Irritant responses were documented by visu al scoring and by measurement of the transepidermal water loss (TEWL) and stratum corneum hydration (electrical capacitance), until day 18. Stratum corneum turnover time (SCTT) was the time in days between stai ning (day 0) and the disappearance of dansyl fluorescence. SLS caused more erythema, scaling, and a significant TEWL increase for 18 days, I n contrast, calcipotriol induced erythema, and slightly but significan tly increased TEWL on day 11 only, as compared with the vehicle contro l (P < 0.05), SLS, but not calcipotriol, caused skin dryness from day 4 to day 18, The shortest SCTT was obtained at SLS-exposed sites (11.2 +/-0.7 days: mean +/- SD), Calcipotriol significantly shortened SCTT ( 16.3 +/- 1.1 days) when compared with its vehicle. Compared with the s kin irritation induced by SLS, under these test conditions, calcipotri ol is a far weaker irritant on normal human skin, In addition, calcipo triol accelerates stratum corneum turnover to a significantly greater extent than its vehicle.