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Difficulty: MediumPsychopharmacology and Psychological Therapies

A 29-year-old woman is brought to the emergency department by her partner due to worsening confusion, extreme restlessness, and tremors. Her temperature is 39.4∘C39.4^{\circ}\text{C} (102.9∘F102.9^{\circ}\text{F}), heart rate is 132/min132\text{/min}, and blood pressure is 164/98 mm Hg164/98\text{ mm Hg}. Physical examination reveals profuse diaphoresis, mydriasis, hyperreflexia, and sustained clonus in the bilateral lower extremities. Her medical history is significant for major depressive disorder treated with sertraline. Two days ago, she began taking an over-the-counter dextromethorphan syrup for a cough. Arrange the following therapeutic interventions in the most appropriate sequential order for managing this patient's condition, starting from the immediate first step to treatments reserved for progressively severe or refractory toxicity.

  1. 1Discontinue all serotonergic medications
  2. 2Administer intravenous fluids and lorazepam
  3. 3Administer oral cyproheptadine
  4. 4Initiate endotracheal intubation and non-depolarizing neuromuscular blockade

Answer

The correct sequence of interventions is: Discontinue all serotonergic medications, followed by administering intravenous fluids and lorazepam, then administering oral cyproheptadine, and finally, if necessary, initiating endotracheal intubation and non-depolarizing neuromuscular blockade.
The correct sequence follows the standard stepwise algorithm for managing serotonin syndrome. The immediate priority is discontinuing the offending serotonergic agents. If symptoms persist, supportive care with intravenous fluids and benzodiazepines (e.g., lorazepam) is initiated to control agitation, lower blood pressure, and reduce heart rate. If the patient's symptoms are moderate to severe and refractory to benzodiazepines, cyproheptadine (a 5-HT2A receptor antagonist) is administered. Finally, in critically severe cases presenting with life-threatening hyperthermia (e.g., >41.1∘C> 41.1^{\circ}\text{C}) and extreme rigidity that threatens respiratory function, endotracheal intubation and non-depolarizing neuromuscular blockade are required to prevent fatal complications.

Step-by-Step Solution

1
Diagnose the patient's condition based on the clinical presentation.
The combination of autonomic instability, altered mental status, and neuromuscular irritability (hyperreflexia, clonus) in the context of taking sertraline and dextromethorphan strongly indicates serotonin syndrome.
Accurate diagnosis is required to determine the appropriate treatment algorithm and anticipate potential complications.
2
Determine the immediate first step in management.
The immediate priority is to stop the offending agents (sertraline and dextromethorphan).
Toxicity will continue or worsen as long as the precipitating serotonergic medications are present.
3
Identify the standard first-line supportive medical treatments.
Supportive care with intravenous fluids and benzodiazepines (such as lorazepam) should be initiated to control agitation and decrease muscle hyperactivity.
Benzodiazepines help manage the hyperdynamic vitals and muscle contractions, serving as the standard initial medical therapy for mild to moderate cases.
4
Identify the next pharmacological step if supportive care fails.
Cyproheptadine should be administered if symptoms are refractory to initial supportive measures.
Cyproheptadine is a specific 5-HT2A receptor antagonist that acts as an antidote, but it is typically reserved for moderate to severe cases not responding adequately to benzodiazepines.
5
Determine the treatment of last resort for extreme, life-threatening toxicity.
Intubation and non-depolarizing neuromuscular blockade are reserved for critically severe cases.
Paralysis prevents further heat generation from extreme muscle rigidity, which is crucial for treating severe hyperthermia (e.g., temperature >41.1∘C> 41.1^{\circ}\text{C}) and preventing rhabdomyolysis.

Key Concept

The management of serotonin syndrome follows a stepwise algorithmic approach: immediate discontinuation of serotonergic agents, supportive care with benzodiazepines, administration of the serotonin antagonist cyproheptadine for refractory cases, and finally intubation/paralysis for life-threatening hyperthermia.
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Topics

Psychopharmacology and Psychological Therapies

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