CONTACT PHOTOALLERGY TO TRIBROMSALICYLANILIDE

SUMMARY. . It has been demonstrated that 5,4′ ‐dibromsalicylanilide (5,4′DBS) and 4′‐monobromsalicy Ianilide (4′MBS) are produced by irradiating 3,5,4′‐tribromsalicylanilide (TBS) and 5,4′DBS respectively in vitro. By further irradiation a coloured product is produced. In patients photosensitized by TBS, experimental photopatch tests have been carried out with these substances and some related agents. The photopatch reactions to 4′MBS were on a level with the reactions to TBS and 5,4′DBS, while only few and weak reactions were elicited with 3,5 DBS and salicylanilide. In 8 of 14 patients 4′MBS elicited positive simple patch tests, the reactions being intensified by u.v. The coloured product evoked strong photopatch test reactions, the simple patch tests being negative in all patients but one. As 4′MBS has been reported not to be affected by u.v. it is suggested that in photosensitization to TBS the 4′‐position and the halogen substituted here is a key point in the sensitization process. Copyright © 1969, Wiley Blackwell. All rights reserved