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Difficulty: MediumPsychopharmacology and Psychological Therapies

A 38-year-old man is brought to the emergency department by his husband due to a sudden, severe, pounding headache, blurred vision, and chest palpitations. The symptoms began approximately 45 minutes ago. The patient has a history of severe, treatment-resistant major depressive disorder. He recently started a new psychiatric medication after trials of several selective serotonin reuptake inhibitors and a serotonin-norepinephrine reuptake inhibitor failed to improve his mood. Earlier this evening, he attended a holiday party where he consumed multiple glasses of tap beer, aged cheddar cheese, and cured sausages. His temperature is 37.2°C (99.0°F), blood pressure is 218/124 mm Hg, pulse is 122/min, and respirations are 18/min. Physical examination reveals a diaphoretic and tremulous man. Neurological examination shows no focal deficits, and an unenhanced head CT scan reveals no abnormalities. Which of the following medications is this patient most likely taking?

  1. A
    Venlafaxine
  2. B
    Amitriptyline
  3. C
    Bupropion
  4. TranylcypromineAnswer
  5. E
    Escitalopram

Answer

Tranylcypromine
The correct answer is tranylcypromine, which is a nonselective monoamine oxidase inhibitor (MAOI). MAOIs (such as tranylcypromine, phenelzine, and isocarboxazid) are highly effective but are typically reserved for treatment-resistant major depressive disorder or atypical depression due to their severe side effect profile and dietary restrictions. Monoamine oxidase-A (MAO-A) in the gastrointestinal tract and liver is responsible for breaking down dietary tyramine, a naturally occurring sympathomimetic amine found in aged cheeses, cured and smoked meats, fermented products, and tap beer. When a patient taking an MAOI consumes these tyramine-rich foods, the un-metabolized tyramine enters the systemic circulation and is taken up by sympathetic nerve terminals. Once inside, it displaces massive amounts of stored norepinephrine from presynaptic vesicles into the synaptic cleft. This sudden surge of catecholamines causes severe alpha-1 adrenergic receptor stimulation, resulting in widespread vasoconstriction and an acute hypertensive crisis. Patients classically present with a sudden severe headache, blurred vision, palpitations, diaphoresis, and dangerously elevated blood pressure. Immediate treatment with an alpha-adrenergic antagonist, such as phentolamine, is often required.

Step-by-Step Solution

1
Evaluate the patient's acute clinical presentation and vital signs.
The patient presents with a severe headache, palpitations, diaphoresis, and severe hypertension (blood pressure 218/124 mm Hg).
Identifying a hypertensive emergency with target organ symptoms (headache, blurred vision) is the first step in determining the underlying etiology.
2
Analyze the patient's psychiatric history and activities prior to symptom onset.
The patient recently started a new medication for treatment-resistant depression and consumed tap beer, aged cheese, and cured meats just before the onset of symptoms.
Connecting the dietary intake of tyramine-rich foods to the onset of the hypertensive crisis narrows the differential diagnosis to a specific drug-diet interaction.
3
Identify the psychiatric medication class associated with this specific dietary interaction.
Monoamine oxidase inhibitors (MAOIs) prevent the gastrointestinal breakdown of dietary tyramine, leading to a profound sympathetic surge.
Tyramine is a sympathomimetic amine that displaces norepinephrine from presynaptic vesicles when its metabolism by MAO-A is inhibited.
4
Select the MAOI from the given pharmacological options.
Tranylcypromine is the only MAOI listed among the options.
Recognizing the specific generic names of MAOIs is required to determine the correct medication causing this patient's crisis.

Key Concept

MAOI-induced hypertensive crisis triggered by tyramine-rich foods
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Topics

Psychopharmacology and Psychological Therapies

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