Almotriptan binds with high affinity to human 5-HT1B and 5-HT1D receptors leading to cranial blood vessel constriction.
Almotriptan is a selective 5-hydroxytryptamine receptor subtype agonist indicated for the acute treatment of migraine attacks with or without aura in adults. Almotriptan is not intended for the prophylactic therapy of migraine or for use in the management of hemiplegic or basilar migraine. Almotriptan is an agonist for a vascular 5-hydroxytryptamine receptor subtype (probably a member of the 5-HT1D family) having only a weak affinity for 5-HT1A, 5-HT5A, and 5-HT7 receptors and no significant affinity or pharmacological activity at 5-HT2, 5-HT3 or 5-HT4 receptor subtypes or at alpha1-, alpha2-, or beta-adrenergic, dopamine1, ; dopamine2; muscarinic, or benzodiazepine receptors. This action in humans correlates with the relief of migraine headache. In addition to causing vasoconstriction, experimental data from animal studies show that Almotriptan also activates 5-HT1 receptors on peripheral terminals of the trigeminal nerve innervating cranial blood vessels, which may also contribute to the antimigrainous effect of Almotriptan in humans.