Neuroleptic malignant syndrome during a change from haloperidol to risperidone

OBJECTIVE: TO report a case of neuroleptic malignant syndrome (NMS) in a pa tient whose therapy was being switched from haloperidol to risperidone. CASE REPORT: A 57-year-old African-American man, treated for schizophrenia with haloperidol for several years, developed NMS within 48 hours of the ad dition of low doses of risperidone and mirtazapine to his regimen. Symptoms , which included fever, generalized rigidity, and altered mental status, re solved after discontinuation of psychotropics, supportive management, and s everal weeks of treatment with bromocriptine and dantrolene. He was subsequ ently treated with olanzapine without adverse effects. DISCUSSION: Several cases of NMS have been reported with risperidone, but n one under these circumstances. NMS most likely occurred in this patient as a result of the additive dopamine, receptor blocking of haloperidol and ris peridone. Sympathetic hyperactivity secondary to mirtazapine may also have been a contributing factor. If NMS may be induced by the simultaneous use o f older, high-potency antipsychotics and newer, atypical antipsychotics suc h as risperidone, switching patients from older to newer antipsychotics may at times be difficult, since completely stopping one antipsychotic before starting the second may place patients at risk for psychotic relapse. CONCLUSIONS: Clinicians should closely monitor patients receiving both halo peridol and risperidone or combinations of similar medications.