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Difficulty: EasyAnxiety, OCD, and Trauma-Related Disorders

A 38-year-old woman with a history of severe social anxiety disorder and treatment-resistant panic disorder is brought to the emergency department by her roommate due to severe agitation, shivering, and confusion. She has been maintained on phenelzine for the past year. Three days ago, her primary care physician prescribed a new daily medication to better manage her ongoing anxiety symptoms, instructing her to stop the phenelzine immediately and start the new drug. Vital signs show a temperature of 39.2°C (102.5°F), blood pressure of 165/100 mm Hg, and pulse of 118/min. Physical examination reveals diaphoresis, dilated pupils, and prominent bilateral clonus in the lower extremities. Which of the following medications was most likely prescribed by the primary care physician?

  1. SertralineAnswer
  2. B
    Alprazolam
  3. C
    Propranolol
  4. D
    Haloperidol
  5. E
    Zolpidem

Answer

Sertraline
The correct answer is sertraline. The patient's presentation of hyperthermia, autonomic instability, altered mental status, and prominent neuromuscular irritability (specifically clonus and hyperreflexia) is the classic triad of serotonin syndrome. This life-threatening condition is most frequently caused by the concurrent use of multiple serotonergic agents. Phenelzine is a monoamine oxidase inhibitor (MAOI). When switching a patient from an MAOI to a selective serotonin reuptake inhibitor (SSRI) like sertraline, a minimum 14-day washout period is absolutely required to allow for the regeneration of the monoamine oxidase enzyme. The primary care physician's instruction to switch immediately precipitated a massive accumulation of serotonin.

Step-by-Step Solution

1
Analyze the patient's clinical presentation and physical examination findings.
The patient exhibits autonomic instability (fever, tachycardia, diaphoresis), altered mental status, and notable neuromuscular irritability (hyperreflexia, clonus).
To recognize the classic triad of symptoms indicative of serotonin syndrome.
2
Review the medication history and recent changes.
The patient was on phenelzine (an MAOI) and was immediately switched to a new medication without a necessary washout period.
To identify the pharmacological mechanism precipitating the acute toxidrome.
3
Determine which class of medication could interact with an MAOI to cause this syndrome.
Selective serotonin reuptake inhibitors (SSRIs) like sertraline strongly interact with MAOIs and require a 14-day washout period to prevent serotonin syndrome.
To select the correct medication from the given options that explains the clinical picture.

Key Concept

Serotonin syndrome is a potentially life-threatening condition caused by excess serotonergic activity, frequently precipitated by combining an MAOI with an SSRI without an adequate 14-day washout period; it classically presents with autonomic instability, altered mental status, and neuromuscular irritability (clonus).
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Topics

Anxiety, OCD, and Trauma-Related Disorders

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