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.