n. any of a class of vasoconstrictor drugs used in the treatment of migraine headache, the prototype of which is sumatriptan. Triptans exert their therapeutic effect by acting as serotonin agonists at 5-HT1B and 5-HT1D receptors, causing the constriction of cerebral blood vessels. Triptans should not be administered concurrently with monoamine oxidase inhibitors and should be used cautiously with SSRIs to avoid the risk of precipitating a serotonin syndrome.