Contact dermatitis to phenothiazine drugs.

Since the advent of use of phenothiazine derivatives as "tranquilizing" drugs, physicians have become aware of the occurrence of severe contact dermatitis in response to administration or handling of certain members of this chemical group (1—3). In addition, clinical observations (4) of the course of jaundice in patients taking oral doses of tranquilizers of this group strongly suggest that other side reactions, notably chlorpromazine hepatitis, may well be allergic manifestations. Hepatitis, as well as agranulocytosis, has been accompanied by skin reactions, and the course of the liver sensitization and desensitization, studied in a group of patients on a protracted course of chlorpromazine therapy, seems to indicate that a similar mechanism of drug sensitivity is involved (5). A peculiar type of retinal toxicity, which also seems to have an allergic basis, has been reported with a phenothiazine drug (6). In this paper we report on a patient in whom skin sensitization developed after exposure to an experimental phenothiazine derivative. Several other analogues were examined by patch testing in order to pinpoint the structural component to which this patient was sensitive. Results seem to indicate a rather specific structure-activity relationship between chlorpromazine and its analogues in causing this cross-reaction.