Sumatriptan

Sumatriptan is a triptan used to treat acute migraine and, with certain injection products, cluster headache attacks in adults. It is not a preventive medicine — it is taken to stop an attack that has already begun.

• Acute treatment of migraine with or without aura in adults — all forms and brands
• Acute treatment of cluster headache in adults — Imitrex injection, Sumatriptan injection, and Sumatriptan Succinate injection only
• Zembrace SymTouch (subcutaneous injection): acute migraine only; not approved for cluster headache
• Onzetra Xsail (nasal capsule), nasal sprays, and tablets: acute migraine only; not established for cluster headache
• No sumatriptan product is indicated for the prevention of migraine or cluster headache

Sumatriptan binds with high affinity to serotonin receptors called 5-HT1B and 5-HT1D, found on blood vessels and sensory nerves inside the skull. Activating these receptors causes the blood vessels to constrict (narrow) and blocks the release of inflammatory chemicals from the trigeminal nerve — the nerve network at the root of migraine pain. The result is relief from the pain and other symptoms of a migraine or cluster headache attack.

Sumatriptan is available in several forms: tablets taken by mouth, nasal sprays, a breath-powered nasal capsule (Onzetra Xsail), and injections given just under the skin. The form, timing, and maximum daily amount differ by product — always follow your prescriber's instructions. Tablets can be taken with or without food, though a high-fat meal may slightly increase absorption. If a first dose helps but the headache returns, a second dose may be taken after the required waiting period, but only if the first dose gave you some relief. Do not use sumatriptan every day to prevent headaches — it is for treating attacks only, and overuse can actually worsen headaches over time.

The most common side effects with sumatriptan include:

• Tingling or numbness
• Warm, hot, or burning sensations
• Feeling of heaviness or pressure
• Flushing (skin redness or warmth)
• Dizziness
• Feeling of tightness
• Injection site reactions (with subcutaneous forms)
• Nasal or throat burning, numbness, or discharge (with nasal forms)

Seek medical help right away if you have chest pain, severe rise in blood pressure, signs of a stroke or heart attack, a serious allergic reaction (swelling, hives, difficulty breathing), or symptoms of serotonin syndrome such as agitation, rapid heartbeat, or high fever.

• Heart risks: Serious cardiac events including heart attack and dangerous heart rhythms have been reported, sometimes in people without known heart disease. Anyone with multiple cardiovascular risk factors needs a cardiac evaluation before starting sumatriptan.
• Stroke and cerebrovascular events: Stroke and bleeding in or around the brain have occurred with triptans. Sumatriptan is contraindicated in anyone with a history of stroke or TIA.
• Blood pressure: Significant blood pressure spikes — including hypertensive crisis — have been reported, even in people without high blood pressure. Sumatriptan is contraindicated in uncontrolled high blood pressure.
• Vasospasm elsewhere in the body: Sumatriptan can cause blood vessel spasm in the gut, limbs, or other areas, leading to symptoms like abdominal pain, bloody diarrhea, or limb coldness.
• Serotonin syndrome: A potentially dangerous buildup of serotonin activity can occur, especially when sumatriptan is combined with certain antidepressants (SSRIs, SNRIs, TCAs) or MAO inhibitors.
• Medication overuse headache: Using acute headache treatments on too many days per month can cause headaches to become more frequent and harder to treat.
• Seizures: Seizures have been reported; use with caution if you have epilepsy or a condition that lowers your seizure threshold.

Sumatriptan has several important drug interactions that can be dangerous:

• Ergot-containing drugs (e.g., dihydroergotamine, methysergide) — cannot be used within 24 hours of sumatriptan; both cause blood vessel constriction and the effects are additive
• Other triptans or 5-HT1 agonists — cannot be combined within 24 hours; same reason as ergots
• MAO-A inhibitors — cannot be used together or within 2 weeks; they dramatically increase sumatriptan levels in the blood (up to 7-fold), raising the risk of serious side effects
• SSRIs, SNRIs, tricyclic antidepressants, and MAO inhibitors — using these together with sumatriptan raises the risk of serotonin syndrome

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

• Tell your prescriber if you have any history of heart disease, angina, heart attack, or arrhythmias such as Wolff-Parkinson-White syndrome
• Tell your prescriber if you have had a stroke, TIA (mini-stroke), or certain types of migraine (hemiplegic or basilar) — sumatriptan is contraindicated in these cases
• Tell your prescriber if you have peripheral vascular disease, ischemic bowel disease, or uncontrolled high blood pressure
• Tell your prescriber if you have liver disease — tablets are contraindicated in severe liver impairment; dose limits apply for mild to moderate impairment
• Tell your prescriber about all other medications, especially antidepressants and any MAO inhibitors
• Pregnancy: Animal studies showed possible fetal harm; discuss the risks and benefits with your doctor before using
• Breastfeeding: Sumatriptan passes into breast milk; consider avoiding nursing for 12 hours after a dose to reduce infant exposure
• Children and adolescents under 18: Effectiveness has not been established; not recommended for this age group
• Older adults: Use cautiously; a cardiovascular evaluation is recommended if heart risk factors are present
• Latex-sensitive patients: the needle shield on some prefilled syringes (Imitrex and Sumatriptan Succinate injection) contains natural rubber latex — alert your provider

If too much sumatriptan is taken, watch for signs such as seizures, tremor, weakness or paralysis, breathing problems, and bluish skin color. The drug has a short half-life of about 2.5 hours, but monitoring should continue for at least 10 hours after an overdose or while any symptoms persist. If you suspect an overdose, contact poison control or seek emergency medical care immediately.

Sumatriptan causes constriction of cranial blood vessels by activating 5-HT1B/1D receptors. Studies in healthy volunteers did not find a clinically significant increase in resistance in small peripheral (outer body) arteries at therapeutic doses. However, significant rises in blood pressure — including hypertensive crisis — have been reported in some patients, with and without a history of high blood pressure. Changes in blood pressure during clinical trials were generally not accompanied by significant changes in heart rate.

When taken by mouth, sumatriptan has an oral bioavailability (the fraction that actually reaches the bloodstream) of only about 15%, mainly because the liver breaks much of it down before it enters circulation. Blood levels peak later during a migraine attack than during a headache-free period. Sumatriptan is broken down primarily by an enzyme called MAO-A, mostly in the liver, and the resulting breakdown products are inactive; only about 3% of a dose leaves the body unchanged. The elimination half-life — the time it takes the body to clear half the drug — is approximately 2.5 hours, with most of the drug leaving through the urine and some through the stool. In people with liver disease, blood levels can be significantly higher than normal, which is why dose adjustments are needed and tablets are contraindicated in severe liver impairment.

Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) (See USP controlled Room Temperature.