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Difficulty: HardPharmacologic Interventions

A 55-year-old man with a history of recurrent major depressive disorder, generalized anxiety disorder, and chronic neuropathic pain is brought to the emergency department by his wife due to confusion, severe agitation, and profuse sweating that began earlier today. His home medications include fluoxetine and gabapentin. Three days ago, he was prescribed tramadol by an orthopedic surgeon for worsening back pain and linezolid by his primary care physician for a suspected methicillin-resistant *Staphylococcus aureus* skin infection. Vital signs are temperature 39.2°C (102.6°F), blood pressure 168/98 mmHg, heart rate 122/min, and respiratory rate 22/min. Physical examination reveals a diaphoretic, agitated man. Neurologic examination shows bilateral hyperreflexia and inducible myoclonus in the lower extremities. Bowel sounds are hyperactive.

Which of the following pharmacologic interventions are appropriate in the immediate management of this patient? (Select all that apply)

  1. Discontinue fluoxetine, tramadol, and linezolidAnswer
  2. Administer intravenous lorazepamAnswer
  3. C
    Administer intravenous bromocriptine
  4. D
    Administer intravenous physostigmine
  5. E
    Administer intravenous fentanyl for pain management

Answer

The appropriate interventions are to immediately discontinue all serotonergic agents (fluoxetine, tramadol, and linezolid) and to administer intravenous lorazepam for symptom control.
The correct interventions involve discontinuing fluoxetine, tramadol, and linezolid, and administering intravenous lorazepam. This patient's presentation of altered mental status, autonomic instability (hyperthermia, tachycardia, hypertension, diaphoresis), and neuromuscular hyperactivity (hyperreflexia and inducible myoclonus) in the context of taking multiple newly prescribed medications confirms the diagnosis of serotonin syndrome. Fluoxetine is a selective serotonin reuptake inhibitor (SSRI), tramadol inhibits serotonin reuptake, and linezolid is an antibiotic that possesses reversible, nonselective monoamine oxidase inhibitor (MAOI) activity. The concomitant use of these drugs profoundly increases intrasynaptic serotonin levels. The cornerstone of acute management is the immediate discontinuation of all serotonergic agents. Additionally, intravenous benzodiazepines (such as lorazepam or diazepam) are the primary pharmacologic therapy used to control agitation, tremor, and autonomic instability.

Step-by-Step Solution

1
Identify the patient's toxidrome based on clinical findings.
The patient exhibits altered mental status, autonomic hyperactivity (fever, tachycardia, hypertension, diaphoresis), and neuromuscular excitability (hyperreflexia, myoclonus).
Recognizing the classic triad of symptoms is essential for diagnosing serotonin syndrome and distinguishing it from other toxidromes.
2
Analyze the patient's recent medication history for interacting agents.
The patient is taking fluoxetine (SSRI), tramadol (SNRI/opioid), and linezolid (an antibiotic that also acts as a nonselective MAOI).
The combination of these multiple serotonergic mechanisms (reuptake inhibition and decreased breakdown) precipitated the severe serotonin toxicity.
3
Determine the appropriate immediate pharmacologic management steps.
Immediate discontinuation of all offending agents and administration of supportive care with benzodiazepines.
Removing the pharmacologic triggers halts further toxicity, while benzodiazepines effectively control agitation, seizures, and hyperdynamic vital signs.

Key Concept

The recognition and acute management of serotonin syndrome, emphasizing the immediate discontinuation of all serotonergic agents (including unexpected culprits like linezolid and tramadol) and the initiation of supportive care with benzodiazepines.
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Pharmacologic Interventions

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