Adrenergic drugs: tyramine reaction: practice question

A Pharmacology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pharmacology · Adrenergic drugs: tyramine reaction

Sample item

A man on phenelzine for atypical depression eats mature cheese and red wine, and an hour later has a severe throbbing headache and blood pressure of 220/130 mmHg. Which drug is most appropriate for immediate treatment?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Intravenous phentolamine

Inhibition of intestinal and hepatic MAO-A allows dietary tyramine to enter the circulation and release large amounts of noradrenaline from nerve endings, causing hypertensive crisis. The pressor effect is alpha1-mediated, so an alpha-blocker such as phentolamine is used. A beta-blocker alone leaves alpha effects unopposed.

Option by option

  • A. Intravenous phentolamine (correct)

    Correct. Phentolamine blocks the alpha1-mediated vasoconstriction.

  • B. Intravenous propranolol

    Propranolol alone leaves alpha-mediated vasoconstriction unopposed and may worsen the pressure.

  • C. Intravenous atropine

    Atropine would add tachycardia and does not reduce vascular resistance.

  • D. Intramuscular adrenaline

    Adrenaline is a pressor and would aggravate the crisis.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

More Pharmacology questions

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is A, Intravenous phentolamine. Inhibition of intestinal and hepatic MAO-A allows dietary tyramine to enter the circulation and release large amounts of noradrenaline from nerve endings, causing hypertensive crisis.

Why is "Intravenous propranolol" not the answer?

Propranolol alone leaves alpha-mediated vasoconstriction unopposed and may worsen the pressure.

Why is "Intravenous atropine" not the answer?

Atropine would add tachycardia and does not reduce vascular resistance.

Why is "Intramuscular adrenaline" not the answer?

Adrenaline is a pressor and would aggravate the crisis.

What concept does this question test?

It tests Adrenergic drugs: tyramine reaction in Pharmacology. The pressor effect is alpha1-mediated, so an alpha-blocker such as phentolamine is used. A beta-blocker alone leaves alpha effects unopposed.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Adrenergic drugs: tyramine reaction?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.