A 32-year-old woman with acute migraine is prescribed sumatriptan. What is the complete pharmacological basis of sumatriptan's anti-migraine efficacy?

• A 5-HT2A antagonism reducing central pain sensitization in the trigeminal nucleus caudalis
• B Selective dopamine D3 receptor blockade reducing nausea and intracranial vascular tone
• C Non-selective 5-HT agonism with additional CGRP receptor blockade providing dual-mechanism headache relief
• D 5-HT1B/1D receptor agonism causing cranial vasoconstriction, inhibition of trigeminal nociceptive transmission, and reduced release of vasoactive neuropeptides (CGRP, substance P) from trigeminal nerve terminals ✓

Explanation

Sumatriptan is a selective 5-HT1B/1D agonist. Activation of 5-HT1B receptors on cranial blood vessels (particularly dural vessels) causes vasoconstriction, countering migraine-associated vasodilation. Activation of presynaptic 5-HT1D receptors on trigeminal nerve endings and neurons in the trigeminal nucleus caudalis inhibits nociceptive signal transmission and blocks release of pro-inflammatory vasoactive neuropeptides including CGRP and substance P. This dual vascular and neuronal mechanism underlies its efficacy in aborting migraine attacks.

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

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Written and medically reviewed by the StethoPrep medical team.