Examkin

Question

Difficulty: HardPharmacologic Interventions

A 5858-year-old woman is evaluated in the intensive care unit for altered mental status, severe agitation, and fever. She has a history of major depressive disorder, generalized anxiety disorder, and chronic back pain. Her home medications include fluoxetine, tramadol, and cyclobenzaprine. Two days ago, she was admitted for severe community-acquired pneumonia and was started on broad-spectrum antimicrobial therapy, including intravenous linezolid. Today, she is diaphoretic and confused. Temperature is 39.4∘C39.4^\circ\text{C} (102.9∘F102.9^\circ\text{F}), blood pressure is 165/100165/100 mmHg, heart rate is 128128/min, and respiratory rate is 2424/min. Physical examination reveals mydriasis, excessive diaphoresis, hyperactive bowel sounds, and inducible myoclonus in the bilateral lower extremities. Which of the following are the most appropriate immediate pharmacologic interventions? (Select all that apply)

  1. Discontinue fluoxetine, tramadol, cyclobenzaprine, and linezolidAnswer
  2. Administer intravenous lorazepamAnswer
  3. Administer cyproheptadine via nasogastric tubeAnswer
  4. D
    Administer intravenous fentanyl for analgesia
  5. E
    Administer intravenous dantrolene

Answer

The correct interventions are to discontinue all serotonergic medications (fluoxetine, tramadol, cyclobenzaprine, and linezolid), administer intravenous lorazepam, and administer cyproheptadine via nasogastric tube.
The correct pharmacologic interventions address the severe serotonin syndrome caused by the interaction between linezolid (an MAOI) and the patient's home serotonergic medications (fluoxetine, tramadol, cyclobenzaprine). The first step is to discontinue all offending agents. Intravenous lorazepam is administered to control agitation and muscle hyperactivity, which subsequently helps reduce hyperthermia. Because the patient has severe toxicity (temperature > 39°C, marked autonomic instability), the specific serotonin antagonist cyproheptadine is indicated and can be administered via a nasogastric tube.

Step-by-Step Solution

1
Identify the underlying toxidrome based on clinical presentation.
The patient presents with autonomic instability, altered mental status, and neuromuscular hyperactivity (myoclonus, hyperreflexia, hyperactive bowel sounds).
These signs form the classic clinical triad of serotonin syndrome, distinguishing it from other hyperthermic syndromes like neuroleptic malignant syndrome.
2
Determine the precipitating pharmacologic cause.
The addition of intravenous linezolid to a home regimen of fluoxetine, tramadol, and cyclobenzaprine.
Linezolid is a reversible, nonselective monoamine oxidase inhibitor (MAOI) that strongly interacts with other serotonergic agents, frequently precipitating severe serotonin syndrome.
3
Select the appropriate immediate pharmacologic management steps.
Discontinue all offending agents, provide supportive care with benzodiazepines, and administer a specific serotonin antagonist.
Immediate withdrawal of serotonergic drugs is essential. Lorazepam controls agitation and hyperthermia. Given the severity (temperature > 39°C), cyproheptadine is indicated as a targeted antidote.

Key Concept

Management of severe serotonin syndrome requires the immediate discontinuation of all serotonergic agents, supportive care with benzodiazepines (e.g., lorazepam) to control agitation and muscle hyperactivity, and the administration of cyproheptadine as a specific serotonin antagonist. Linezolid is a common iatrogenic trigger due to its MAOI properties.
Rate this question

Topics

Pharmacologic Interventions

More questions from this topic