A patient taking tranylcypromine attends a party and consumes aged cheese and red wine. Two hours later he presents with severe headache, blood pressure 220/130 mmHg, and sweating. The mechanism of this hypertensive crisis is:

• A Direct alpha-1 agonist action of tyramine on vascular smooth muscle
• B Displacement of stored norepinephrine from adrenergic nerve terminals by tyramine ✓
• C Inhibition of norepinephrine reuptake at central synapses
• D Potentiation of circulating epinephrine by reduced COMT activity

Explanation

Tyramine is an indirectly acting sympathomimetic taken up by transport into noradrenergic terminals, where it displaces stored norepinephrine from vesicles. Normally intestinal and hepatic MAO-A destroys dietary tyramine; with MAO inhibition it reaches the circulation intact and triggers a massive pressor response. Option D fails because COMT inhibition by itself is clinically insignificant for this interaction.

Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.