Neuroleptic malignant syndrome associated with the use of prochlorperazine in a patient with a recent history of antipsychotic-induced neuroleptic malignant syndrome

Ann Pharmacother. 2011 Nov;45(11):e61. doi: 10.1345/aph.1Q325. Epub 2011 Oct 4.


Objective: To describe a case of neuroleptic malignant syndrome (NMS) associated with the use of prochlorperazine in a patient recently hospitalized for NMS secondary to olanzapine.

Case summary: A 28-year-old African American male with a history of schizophrenia was hospitalized 22 days prior to the current admission for an episode of olanzapine-induced NMS. The patient was discharged from our hospital to an outside psychiatric facility. At this facility, the patient developed nausea and was given 2 doses (unknown amount and route) of prochlorperazine. Over the next 24 hours, the patient exhibited signs and symptoms of NMS including fever, agitation, and muscle rigidity. He was transported to the emergency department and became increasingly agitated. Upon admission, the patient was hyperthermic (rectal temperature 39 °C) and tachycardic (heart rate 138 beats/min), with an elevated white blood cell count of 13.5 × 10(3)/μL, creatine kinase 431 units/L, serum sodium 150 mEq/L, blood urea nitrogen 25 mg/dL, and creatinine 1.1 mg/dL. A diagnosis of NMS was speculated and infectious causes were excluded. The patient was treated with aggressive fluid resuscitation and rapid cooling measures, as well as bromocriptine and lorazepam. Cooling measures were used for 48 hours, during which time the creatine kinase, white blood cell count, sodium, blood urea nitrogen, and creatinine gradually normalized. The patient was discharged to a psychiatry facility with a treatment regimen of oxcarbazepine 600 mg twice daily, lorazepam 2 mg 3 times daily, and clozapine 25 mg at bedtime, which was titrated over 2 months to 200 mg twice daily. There have been no further occurrences of NMS.

Discussion: The patient had all of the major characteristics of NMS with no other likely causative factors that may have contributed to his illness. Use of the Naranjo probability scale suggested that NMS was probably related to prochlorperazine. This case highlights the potential increased risk with the use of prochlorperazine in a patient with a history of olanzapine-induced NMS.

Conclusions: NMS should be considered as a rare complication of therapy with antipsychotics and agents that alter dopamine activity, especially in patients with a history of the syndrome. Careful consideration should be given regarding the risks and benefits of using non-antipsychotic dopamine antagonists in patients with a history of antipsychotic-induced NMS.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Antipsychotic Agents / adverse effects*
  • Antipsychotic Agents / therapeutic use
  • Benzodiazepines / adverse effects
  • Benzodiazepines / therapeutic use
  • Humans
  • Male
  • Neuroleptic Malignant Syndrome / drug therapy*
  • Neuroleptic Malignant Syndrome / etiology*
  • Olanzapine
  • Prochlorperazine / adverse effects*
  • Prochlorperazine / therapeutic use
  • Schizophrenia / drug therapy


  • Antipsychotic Agents
  • Benzodiazepines
  • Olanzapine
  • Prochlorperazine