Poor availability due to presystemic metabolism
Volume of distribution 2.7 L/kg [subcutaneous dosing]
Selective agonist of vascular serotonin ((5-hydroxytryptamine; 5-HT) type 1-like receptors, likely the 5-HT1D and 5-HT1B subtypes
The 5-HT1B and 5-HT1D receptors function as autoreceptors
Adenylate cyclase activity is inhibited via regulatory G proteins; increases intracellular calcium, and affects other intracellular events
Inhibits the firing of serotonin neurons and cause a reduction in the synthesis and release of serotonin upon activation
Has no significant affinity or pharmacological activity at:
5-HT2, 5-HT3 receptor subtypes
Alpha1-, alpha2-, or beta-adrenergic receptors
Dopamine1 or 2 receptors
This results in vasoconstriction and inhibtion of sensory nociceptive (trigeminal) nerve firing and vasoactive neuropeptide release.
In vitro studies with human microsomes suggest that sumatriptan is metabolized by monoamine oxidase (MAO), predominantly the A isoenzyme.
Only 3% of the dose is excreted in the urine as unchanged sumatriptan
42% of the dose is excreted as the major metabolite, the indole acetic acid analogue of sumatriptan
Half-life 2.5 hrs
Symptoms of overdose include convulsions, tremor, paralysis, inactivity, ptosis, erythema of the extremities, abnormal respiration, cyanosis, ataxia, mydriasis, salivation, and lacrimation