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Difficulty: HardPharmacologic Interventions

A 45-year-old man is brought to the emergency department by his family due to altered mental status, severe muscle stiffness, and high fever that began 24 hours ago. His medical history is significant for schizoaffective disorder, for which he has been taking clozapine and lithium for several years. Two days ago, he was prescribed oral haloperidol at an urgent care clinic for an acute exacerbation of severe agitation.

Vital signs are temperature 39.4°C (102.9°F), pulse 122/min, respirations 22/min, and blood pressure 168/100 mmHg. Physical examination reveals a diaphoretic, confused man. Neurologic examination is notable for severe, generalized "lead-pipe" muscle rigidity and decreased bowel sounds. Hyperreflexia and clonus are absent.

Laboratory studies show:
Leukocyte count: 16,500/mm³
Serum creatine kinase: 15,400 U/L
Serum creatinine: 2.1 mg/dL (baseline 0.9 mg/dL)

Which of the following pharmacologic interventions are appropriate in the management of this patient's current condition? (Select all that apply)

  1. Administration of bromocriptineAnswer
  2. Administration of dantroleneAnswer
  3. Aggressive intravenous fluid resuscitationAnswer
  4. D
    Administration of cyproheptadine
  5. E
    Administration of intravenous benztropine

Answer

The appropriate interventions are administration of bromocriptine, administration of dantrolene, and aggressive intravenous fluid resuscitation.
The patient is presenting with Neuroleptic Malignant Syndrome (NMS), a life-threatening neurologic emergency caused by dopamine receptor blockade (precipitated here by haloperidol). Classic findings include altered mental status, autonomic instability, severe hyperthermia, and "lead-pipe" muscle rigidity. A major complication of this prolonged rigidity is rhabdomyolysis (evidenced by severely elevated creatine kinase), which subsequently causes acute kidney injury (elevated creatinine). The most critical initial step in management is the immediate discontinuation of the offending neuroleptic agent. From a pharmacologic standpoint, management requires aggressive supportive care, primarily consisting of aggressive intravenous fluid resuscitation to maintain renal perfusion, clear myoglobin, and prevent worsening of acute kidney failure. In moderate to severe cases, specific targeted pharmacotherapy is indicated. Dopamine agonists, such as bromocriptine or amantadine, are administered to directly overcome the dopamine receptor blockade. Dantrolene, a direct-acting skeletal muscle relaxant, is also utilized to rapidly reduce severe muscle rigidity and assist in managing hyperthermia.

Step-by-Step Solution

1
Diagnose the patient's acute toxidrome based on clinical presentation.
The patient has Neuroleptic Malignant Syndrome (NMS).
The recent initiation of haloperidol (a typical antipsychotic) followed by fever, autonomic instability, altered mental status, and classic "lead-pipe" rigidity confirms NMS.
2
Identify disease complications from the laboratory results.
The patient has rhabdomyolysis and acute kidney injury (AKI).
Severe muscle rigidity leads to muscle breakdown (creatine kinase 15,400 U/L), releasing myoglobin which causes nephrotoxicity (creatinine 2.1 mg/dL).
3
Select the appropriate targeted pharmacologic therapies and supportive measures.
Bromocriptine, dantrolene, and intravenous fluids are indicated.
Along with stopping haloperidol, dopamine agonists (bromocriptine) reverse the blockade, dantrolene relaxes muscles, and IV fluids treat rhabdomyolysis-induced AKI.

Key Concept

Pharmacologic management of Neuroleptic Malignant Syndrome (NMS)
Estimated Time:1m 30s
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Topics

Pharmacologic Interventions

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