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Eight patients suffering from pigmented contact dermatitis caused by the commercial Brilliant Lake Red R were patch tested with purified Sudan I and its several chemical analogues. Positive reactions were observed to Sudan I, Orange SS, Brilliant Lake Red R, Vacanceine Red, Yellow OB and Sudan II. Negative patch tests were obtained with Toluidine Red, Permanent Orange, Lithol Red and Sudan III. We found that the commercial Brilliant Lake Red R which had been said to be the most important causative agent of pigmented contact dermatitis, contained Sudan I as a major impurity. The patients reacting to Brilliant Lake Red R always gave a positive reaction to Sudan I, but those reacting to Sudan I did not always give a positive reaction to Brilliant Lake Red R. This suggests that Sudan I is a potent sensitizer and may induce contact sensitivity and that Brilliant Lake Red R itself is a weak sensitizer or a cross-reacting substance. [ABSTRACT FROM AUTHOR]

Eight patients suffering from pigmented contact dermatitis caused by the commercial Brilliant Lake Red R were patch tested with purified Sudan I and its several chemical analogues. Positive reactions were observed to Sudan I, Orange SS, Brilliant Lake Red R, Vacanceine Red, Yellow OB and Sudan II. Negative patch tests were obtained with Toluidine Red, Permanent Orange, Lithol Red and Sudan III. We found that the commercial Brilliant Lake Red R which had been said to be the most important causative agent of pigmented contact dermatitis, contained Sudan I as a major impurity. The patients reacting to Brilliant Lake Red R always gave a positive reaction to Sudan I, but those reacting to Sudan I did not always give a positive reaction to Brilliant Lake Red R. This suggests that Sudan I is a potent sensitizer and may induce contact sensitivity and that Brilliant Lake Red R itself is a weak sensitizer or a cross-reacting substance. [ABSTRACT FROM AUTHOR]

Twenty-three patients suffering from pigmented contact dermatitis caused by cosmetics containing Brilliant Lake Red R were observed. Commercial samples of Brilliant Lake Red R proved to contain many ethyl acetate extractable impurities: 1-phenylazo-2-naphthol and azobenzene were isolated and identified. To determine the responsible allergens, five patients were examined by patch tests with purified samples of azo-dyes and the unidentified fractions of ethyl acetate extractable impurities. Three out of five showed weaker reactions to purified samples of Brilliant Lake Red R and the other two showed equal reactions compared to the commercial product. 1-Phenylazo-2-naphthol was found to be a strong allergen in all cases but none showed a positive reaction to azobenzene. Some unidentified fractions also gave positive results. Patch tests were performed with 4-phenylazo-1-naphthol, 4-phenylazo-1-naphthol-2-carboxylic acid, and 2,4-bis(phenylazo)-1-naphthol, as structurally related compounds derived from 1-naphthol. All gave negative and they were not detected in the ethyl acetate extractable impurities by thin-layer chromatography. [ABSTRACT FROM AUTHOR]

A sixty-year-old man, with four year history of gout, used indomethacin ointment for painful episodes. He then used the same ointment on the lower leg for itchy skin. After some time, an erythema developed on the extensor surface of legs and lesions gradually worsened. Treatment with oral antihistamine and topical steroid was ineffective. Oral prenisolone was given and resulted in rapid healing of the skin condition. The patient was first tested by the topical application of indomethacin ointment, which was applied at the back. An itchy eruption was seen at the application site after two days.