Clozapine-induced systemic lupus erythematosus.

Objective: To report a case of classic clozapine-induced systemic lupus erythematosus that also developed on rechallenge.

Case Summary: A 32-year-old white woman diagnosed with schizophrenia presented in 1996 with clinical characteristics and laboratory markers consistent with drug-induced lupus (DIL). Clozapine, started 1 year prior, was withdrawn, with complete biological and clinical remission within 3 months. In 2004, 1 week after rechallenge with clozapine for uncontrolled schizophrenia, the patient developed clinical and biological signs and symptoms consistent with the diagnosis of DIL. Again, discontinuation of clozapine was followed by full remission within 2-3 months.

Discussion: DIL was first described more than 50 years ago, with multiple drugs implicated in the causation. Clozapine-induced lupus was reported recently, but does not meet the usual criteria for a diagnosis of DIL. We report a classic case of clozapine-induced lupus that, according to the Naranjo probability scale, demonstrates a highly probable relationship between DIL and clozapine.

Conclusions: DIL demands a high index of suspicion for diagnosis. Although clozapine has an extensive safety profile, DIL must be considered as one of its serious adverse effects.