THE CALCIPOTRIOL DOSE-IRRITATION RELATIONSHIP - 48-HOUR OCCLUSIVE TESTING IN HEALTHY-VOLUNTEERS USING FINN CHAMBERS(R)

Calcipotriol is widely used in the treatment of psoriasis. Adverse les ional and perilesional irritation may occur. Allergy may occasionally be suspected. Allergy patch testing with calcipotriol may be difficult or impossible because calcipotriol is a local irritant. The aim of th e present study was to assess the calcipotriol dose-irritation relatio nship, and establish a non-irritant patch test concentration for calci potriol allergy patch testing. The study was a prospective, double-bli nd, randomized, dose titration evaluation in 180 healthy volunteers ne ver previously exposed to calcipotriol. All individuals were patch tes ted with a calcipotriol dilution series (range 0.016-250 mu g/mL). Cli nical reading of test sites and measurement of erythema using a Minolt a ChromaMeter were performed on days 2 and 3. Laser Doppler perfusion imaging of cutaneous blood now was performed on day 3. Doubtful reacti ons (score 1/2) and weak reactions (score 1) were frequent and observe d even at low dose exposure. Reactions declined in strength between th e readings on day 2 and day 3. Only score 3 reactions with moderate er ythema and some infiltration showed a threshold of no irritation. This threshold was confirmed by colorimetry and flowmetry. Cases of suspec ted allergy to calcipotriol may, to avoid irritant reaction and false positive readings, be patch tested with calcipotriol 2 mu g/mL citrate -buffered isopropanol solution applied under occlusion for 48 h using small Finn Chambers(R). Score 1/2 and 1 reactions are likely to reflec t irritation. A positive test should be repeated after a minimum perio d of 3 months to ensure its consistency over time. A repeated open app lication test may be indicated.