Migraines are likely due to local cranial vasodilatation and/or to the release of sensory neuropeptides through nerve endings in the trigeminal system. The therapeutic activity of Zolmitriptan?for the treatment of migraine headache is thought to be due to the agonist effects at the 5-HT1B/1D receptors on intracranial blood vessels and sensory nerves of the trigeminal system which results in cranial vessel constriction and inhibition of pro-inflammatory neuropeptide release.