An unexpected and serious complication of treatment with the atypical antipsychotic drug clozapine.

A 49-year-old man developed acute renal failure due to interstitial nephritis during treatment with the drug clozapine. Referral and diagnosis were delayed through a failure to consider complications of treatment other than neuroleptic malignant syndrome. Although this association has not previously been reported in the literature, we include details of a further 7 cases of acute renal failure in association with clozapine therapy reported to the Committee On Safety Of Medicines in the UK.