Sumatriptan is effective in acute migraine. A patient with migraines also has Prinzmetal's (variant) angina. Sumatriptan is CONTRAINDICATED in this patient because:

• A Sumatriptan inhibits serotonin reuptake, increasing synaptic 5-HT and triggering vasospasm in coronary vessels
• B Sumatriptan blocks CGRP receptors, removing CGRP-mediated coronary vasodilation and unmasking vasospasm
• C Sumatriptan is a 5-HT1B/1D agonist; 5-HT1B receptor activation causes vasoconstriction in intracranial AND coronary vessels, precipitating coronary vasospasm ✓
• D Sumatriptan inhibits COX-2 in cardiac endothelium, reducing prostacyclin and promoting platelet aggregation in coronary vessels

Explanation

Sumatriptan is a selective 5-HT1B/1D receptor agonist. 5-HT1B receptors are present on intracranial blood vessels (where their activation produces therapeutic cranial vasoconstriction and anti-migraine effect) but ALSO on coronary arteries. In patients with Prinzmetal's angina (who have hyperreactive coronary smooth muscle), 5-HT1B-mediated coronary vasoconstriction can precipitate life-threatening coronary vasospasm and myocardial ischemia. Sumatriptan does not inhibit serotonin reuptake, does not block CGRP receptors (gepants do), and has no COX inhibitory activity.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.