Search for a new anti-migraine drug started at Glaxo in 1972. Studies in the 1960s showed that vasoconstriction from 5-HT, ergotamine and noradrenaline could reduce migraine attacks. Research also showed that platelet 5-HT level is reduced during migraine. Because there are too many side-effects for 5-HT to be used as a drug, scientists started research on the receptors of 5-HT in order to discover and develop a more specific agonist for 5-HT receptors. Research on the 5-HT receptors and their effect led to discovery of several types and subtypes of 5-HT. AH24167 showed a vasodilation effect instead of vasoconstriction due to the agonist effect on another type of 5-HT receptors later assigned the name 5-HT. AH25086 was the second compound developed and showed a vasoconstriction effect but was not released as a drug due to low per oral bioavailability. Continued research led to the discovery of the first triptan drug, sumatriptan, that had both vasoconstriction effect, as well as better oral bioavailability. Sumatriptan was first launched in the Netherlands in 1991 and became available in the United States during 1993.