CHLOROMETHYLISOTHIAZOLONE METHYLISOTHIAZOLONE (CMI MI) USE TEST WITH A SHAMPOO ON PATCH-TEST-POSITIVE SUBJECTS - RESULTS OF A MULTICENTER DOUBLE-BLIND CROSSOVER TRIAL/

A randomized, multicentre, double-blind, 2-period crossover study with 2 shampoos was performed on subjects patch-test-positive to 100 ppm C MI/MI. One shampoo was preserved with 15 ppm a.i. CMI/MI, the other wi th 0.3% imidazolidinyl urea (IU). 27 subjects from 5 European dermatol ogy clinics participated. 1 subject discontinued use after severe adve rse reactions to the CMI/MI-preserved shampoo and did not evaluate the other shampoo. Another 2 subjects developed moderate symptoms with th e CMI/MI-preserved shampoo and discontinued its use, but tolerated the IU-preserved shampoo for the full 2-week period. 2 subjects discontin ued use after 1 or 2 washes after severe adverse reactions to the IU-p reserved shampoo. 1 of these subjects tolerated the CMI/MI-preserved s hampoo for 2 weeks without any untoward effects. However, the majority of subjects had negative findings on the scalp, face, neck, and hands for both shampoos. The physicians' global evaluation data indicated t hat shampoo with CMI/MI caused fewer skin problems than shampoo with I U (38% versus 27%, n.s.), with over 1/3 of the subjects (35%) having n o skin problems with either preservative. The current study showed tha t most subjects previously sensitized to CMI/MI can successfully use s hampoo preserved with CMI/MI. Since some subjects previously sensitize d to CMI/MI, or possibly to IU, may develop clinical reactions, it wou ld still be prudent for the clinician to advise alternative products t o patients with sensitivity to a shampoo or cosmetic ingredient. Full ingredient labelling will ensure that this is possible. As the overall rate of adverse effects in sensitized individuals was low, studies of this nature should also be conducted for other allergens. This will b e helpful in determining the relevance of patch test data.