All of the following drugs are used in Migraine prophylaxis EXCEPT:

(B) Sumittriptan # Sumatriptan is structurally similar to serotonin (5HT), and is a 5-HT (types 5-HT1D and 5-HT1B) agonist.> Specific receptor subtypes it activates are present on the cranial arteries and veins. Acting as an agonist at these receptors, Sumatriptan reduces the vascular inflammation associated with migraine.> The specific receptor subtype it activates is present in the cranial and basilar arteries. Activation of these receptors causes vasoconstriction of those dilated arteries.> Sumatriptan is also shown to decrease the activity of the trigeminal nerve, which, it is presumed, accounts for sumatriptan's efficacy in treating cluster headaches.> It is given at the onset of an attack.