Although sumatriptan's mechanism of action has not been established , suppression of migraine headaches may result from sumatriptan –induced decreases in the firing of serotonergic (5-HT ) neurons. Specifically , it is thought that agonist activity at the 5- HT1D receptor subtype provides relief of acute headache . It has been proposed that constriction of cerebral blood vessels resulting from 5-HT1D receptor stimulation reduces the pulsation that may be responsible for the pain of vascular headaches . It has also been proposed that neurogenic inflammation in areas innervated by the trigeminal nerve may contribute to the development of migraine headaches ; there is some evidence that serotonergic mechanisms may be involved . Sumatriptan may also relieve migraines by decreasing release of neuropeptides and other mediators of inflammation and by reducing extravastion of plasma proteins.

Sumatriptan is indicated to relieve acute migraine headaches ( with or without aura ) in patients who do not obtain sufficient relief with analgesics . Sumatriptan also relieves the nausea , vomiting , photophobia , and phonophobia that frequently occur in association with migraine headaches . Sumatriptan is not recommended for long –term migraine prophylaxis and for treatment of basilar artery migraine or hemiplegic migraine.

Dizziness; Flushing ; Weakness ; Drowsiness ; Lightheadedness ; Fatigue ; Nausea; Vomiting ; Pain or sensations of tingling , heaviness , heat , pressure , or tightness in chest and/or neck ; Hypotension ; Bradycardia or tachycardia ; Palpitations ; Visual disturbances ; Minor disturbances in liver function ; Seizures ; Skin rashes ; Anaphylaxis ; Muscle aches , cramps , or stiffness ; Anxiety

Hypersensitivity to sumatriptan or any component of the formulation ; Patients with ischemic heart disease ; Cerebrovascular syndromes ; Peripheral vascular syndromes ( including ischemic bowel disease ) ; Uncontrolled hypertension ; Use within 24 hours of ergotamine derivatives ; Use within 24 hours of another 5-HT1 agonist ; Concurrent administration or within 2 weeks of discontinuing a MAO inhibitor , specifically MAO type A inhibitors ; Management of hemiplegic or basilar migraine ; Prophylactic treatment of migraine ; Severe hepatic impairment.

Sumatriptan is indicated only in patients > or = 18 years of age with a clear diagnosis of migraine . Safety and efficacy in pediatric patients have not been established . Do not give to patients with risk factors for CAD until a cardiovascular evaluation has been performed . Use with caution in patients with history of seizure disorder or in patients with a lowered seizure threshold.

Ergot –containing drugs (dihydroergotamine , ergotamine or methysergide) prolong vasospastic reactions ; do not use sumatriptan with them within 24 hours of each other . MAO inhibitors type A (furazolidone , isocarboxazid , meclobemide , phenelzine , toloxatone , and tranylcypromine ) reduce sumatriptan clearance ; concurrent use is contraindicated ; wait at least 2 weeks after discontinuing MAO inhibitor type A to start sumatriptan . While not specifically contraindicated , combination with selegiline ( a selective MAO inhibitor type B) may best be avoided until further study . Concurrent use of sumatriptan with SSRIs ( fluoxetin , fluvoxamine , paroxetine , sertraline ) can lead to symptoms of hyper –reflexia , weakness , and incoordination ; careful monitoring is recommended . Use sumatriptan cautiously in patients receiving concomitant medications that can lower the seizure threshold.

• Usual adult dose: Oral , 25,50 or 100 mg as a single dose . If necessary , additional doses up to 100 mg may be taken at intervals of at least two hours , up to 200 mg a day . For relief of migraine headache that returns after an initial treatment with sumatriptan tablets : the dose may be repeated after two hours , up to a maximum of 200 mg once a day.
• Usual adult prescribing limits: Oral , not more than 200 mg in 24 hours.
• Usual pediatric dose: Safety and efficacy in patients up to 18 years of age have not been established.

• USP DI, 2004
• Up To Date, Vol. 13.1 (2005)
• Martindale, The Complete Drug Reference, 33 rd edition 2002