Use of sumatriptan evolved due to the role of serotonin (5-hydroxytryptamine, 5-HT) in the pathophysiology of migraine. Vasodilatation within the cerebral circulation was recognized to contribute to the severity of headache. Intravenous serotonin was shown to alleviate migraine headache, although side effects were considerable (Kimball et al 1960). Sumatriptan resembles serotonin in its structure and, as a 5-HT1 agonist, was developed to stimulate the 5-HT receptors on the blood vessels, reduce vasodilatation, and, thus, reduce headache. Events leading to the development of sumatriptan have been reviewed elsewhere (Saxena and Ferrari 1992). Clinical trials with sumatriptan started around 1989, and the product is now used worldwide. Six other triptan products have received FDA approval since the 1990s, but sumatriptan remains the most widely prescribed product.