1. Clinical Overview
Sumatriptan is a selective serotonin (5-HT1B/1D) receptor agonist, classified as a triptan, used for the acute treatment of migraine and cluster headache attacks. It is a first-line abortive therapy for moderate to severe migraine with or without aura. It works by causing vasoconstriction of cranial blood vessels, inhibiting neurogenic inflammation, and blocking pain pathways in the trigeminal system.
| Onset | Duration | Bioavailability |
|---|---|---|
| 10-15 minutes (nasal spray), 30-60 minutes (oral tablet) | Up to 24 hours for headache relief | Approximately 15% (oral), 17% (nasal spray) |
2. Mechanism of Action
Sumatriptan binds with high affinity to serotonin 5-HT1B and 5-HT1D receptors. Activation of 5-HT1B receptors on intracranial blood vessels (including arteriovenous anastomoses) leads to vasoconstriction, reversing the vasodilation associated with migraine. Activation of 5-HT1D receptors on sensory nerve endings of the trigeminal vascular system inhibits the release of pro-inflammatory neuropeptides (e.g., CGRP, substance P), thereby reducing neurogenic inflammation and pain signal transmission to the brainstem.
3. Indications & Uses
- Acute treatment of migraine attacks with or without aura
- Acute treatment of cluster headache episodes (typically using nasal spray or injection)
4. Dosage & Administration
Adult Dosage: Migraine: Oral: 50-100 mg as a single dose, may repeat after 2 hours if needed (max 200 mg/24h). Nasal Spray: 20 mg (one spray in one nostril). If headache recurs, may repeat once after 2 hours (max 40 mg/24h). Cluster Headache: SC Injection 6 mg (preferred) or Nasal Spray 20 mg.
Administration: Oral Tablet: Swallow whole with water. Take at the first sign of migraine pain. Nasal Spray: Prime the pump before first use. Blow nose gently. Close one nostril, tilt head slightly back, insert nozzle into other nostril. Breathe in gently while spraying. Avoid deep inhalation. Do not use if seal is broken. Do not use more than 2 doses in 24 hours.
5. Side Effects
Common side effects may include:
- Tingling/heat sensation (paresthesia)
- Heaviness/pressure sensation in chest/neck/throat (non-cardiac)
- Dizziness/vertigo
- Fatigue/drowsiness
- Nausea/vomiting
- Unpleasant taste (with nasal spray)
- Nasal discomfort/irritation (with nasal spray)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Monoamine Oxidase-A Inhibitors (e.g., Moclobemide, Clorgyline) | Markedly increased sumatriptan plasma levels and prolonged half-life. Risk of serotonin syndrome. | Contraindicated |
| Ergot Alkaloids (e.g., Ergotamine, Dihydroergotamine) | Prolonged vasospastic reactions. Additive vasoconstriction. | Contraindicated (within 24 hours) |
| Other Triptans (e.g., Rizatriptan, Zolmitriptan) | Additive vasoconstriction, increased risk of adverse effects. | Contraindicated (within 24 hours) |
| Selective Serotonin Reuptake Inhibitors (SSRIs) / SNRIs (e.g., Sertraline, Fluoxetine, Venlafaxine) | Increased risk of serotonin syndrome (weakness, hyperreflexia, incoordination). | Major |
| St. John's Wort | Increased serotonergic effects, risk of serotonin syndrome. | Major |
| Propranolol | Increased plasma concentration of sumatriptan (by ~50%). | Moderate |
7. Patient Counselling
- DO take at the first sign of migraine headache.
- DO NOT use for more than 2 days per week on a regular basis to avoid medication-overuse headache.
- DO NOT take a second dose for the same attack if the first dose provides no relief without consulting a doctor.
- DO NOT use to prevent migraines.
- DO lie down in a quiet, dark room after taking the dose if possible.
- DO inform your doctor of all other medications you are taking, especially antidepressants.
8. Toxicology & Storage
Overdose: Symptoms may include hypertension, cardiovascular collapse, tremor, seizures, paralysis, cyanosis, respiratory depression, and loss of consciousness. In animals, large overdoses led to convulsions, ataxia, and sedation.
Storage: Store below 30°C. Protect from light and moisture. Keep the nasal spray in its original container. Keep out of reach of children.