Chlorpromazine‐induced lupus anticoagulant and associated immunologic abnormalities

Abstract

Chronic administration of chlorpromazine is associated with the development of a lupus-like circulating anticoagulant and a variety of immunological abnormalities. The prevalence of these findings was studied in 123 psychiatric patients. The anticoagulant was present in 11 of 30 patients receiving chlorpromazine (CPZ), in none of 17 patients who had been off phenothiazine therapy for over a year and in none of 53 controls. It was also seen in 5 of 13 patients who had been switched from CPZ to another phenothiazine even after several years being off CPZ. The anticoagulant was characterized by prolongation of the partial thromboplastin time, thromboplastin dilution test, and Russell's viper venom time. Washed frozen platelets partially corrected the abnormality induced by the anticoagulant. In all but one case the anticoagulant was associated with positive antinuclear antibody test and/or increased serum IgM. Six of 16 patients also had decreased complement levels, and two had a positive direct Coombs' test. None of these patients manifested bleeding, hemolysis, splenomegaly, or other clinical features of systemic lupus erythematosus.