Where do triptans act in the treatment of migraine?

Migraine headache is a pervasive but poorly understood primary pain disorder.Sumatriptan and the 'triptan' class of serotonin receptor subtype-selective drugs have well-established efficacy in treating the pain of migraine.Although sumatriptan was originally selected to target vasoactive properties thought to be fundamental to the etiology of migraine, other studies point to an action of triptans at several levels of the nervous system.To this day, however, it is not clear whether the antimigraine activity of the triptans involves an action only in the periphery or in the CNS as well.Because sumatriptan is hydrophilic, it penetrates the blood-brain barrier poorly, suggesting a peripheral site of action.On the other hand, it has been proposed that the barrier is compromised in migraineurs, so a CNS site of action has not been ruled out.Finally, the basis for the apparent selectivity of triptans in the treatment of migraine pain but not other kinds of somatic pain is still not understood.Determining that mechanism of triptan action will likely provide important new insights into the unique and essential features of migraine.