Sumatriptan
Sumatriptan
Generic Name
Sumatriptan
Mechanism
Sumatriptan is a selective 5‑HT1B/1D serotonin receptor agonist that
• stimulates peripheral 5‑HT1B receptors on cranial blood vessels, causing vasoconstriction and decreased inflammatory mediator release;
• activates 5‑HT1D receptors on trigeminal afferents, inhibiting neuropeptide release and neurotransmission;
• ultimately aborts the acute migraine attack by reducing neurogenic inflammation and cranial arterial dilation.
Pharmacokinetics
- Absorption: Rapid oral absorption (∼70 % bioavailability); nasal spray achieves ∼80 % systemic exposure, subcutaneous injection 100 %.
- Onset: 15–30 min (oral), 4–5 min (nasal), 3–5 min (SC).
- Distribution: Moderate protein binding (~50 %).
- Metabolism: Mainly hepatic via CYP1A2, CYP2C19/2A6; negligible renal excretion.
- Elimination: T½ ~3.5–4 h; 10–15 % excreted unchanged in urine.
- Drug interactions: Strong CYP1A2 inhibition or induction alters exposure; caution with monoamine‐oxidase inhibitors, other triptans, and serotonin‑reuptake inhibitors.
Indications
- Acute migraine attacks (with or without aura) in adults and children 12 y+;
- Acute cluster headache (nasal spray and SC formulations).
- Auxiliary indications: acute headaches in certain surgical settings (e.g., post‑operative), prophylaxis not indicated.
Contraindications
- Contraindications:
- Known allergy to sumatriptan or excipients;
- Severe cardiovascular disease (ischemic heart disease, uncontrolled hypertension, arrhythmias);
- History of stroke or cerebrovascular disease;
- Severe hepatic impairment.
- Warnings:
- Serotonin syndrome risk when combined with serotonergic agents;
- Potential for vasospasm in patients with high cardiovascular risk;
‑ Monitor for ischemia symptoms in patients with pre‑existing cardiac disease;
• Not recommended during pregnancy (Category C) and postpartum lactation.
Dosing
| Formulation | First dose | Max daily dose | Timing | Notes |
| Oral tablet (75–100 mg) | 75 mg (≤2 mg/m²) | ≤200 mg / day | 1–2 h after symptom onset | If inadequate, repeat after 2 h (max 200 mg/day). |
| Oral tablet (50 mg) | 50 mg | 200 mg / day | 2–3 h | Adjust dose in renal/hepatic compromise. |
| Nasal spray (20 µg/actuation) | 1–2 sprays | 1 spray per hour | 0–5 min | Useful in patients with nausea or vomiting. |
| Subcutaneous injection (6 mg) | 1 mg | 6 mg / day | 15–30 min | Preferred for severe migraine or when oral/NAS inadequate. |
| Intramuscular injection (6 mg) | 1 mg | 6 mg / day | 15–30 min | Alternative in outpatient settings. |
Adverse Effects
Common (≥10 %)
• Fatigue, dizziness, paresthesia, flushing, myalgia, nausea, shortness of breath, headache
• Palpitations, abdominal pain, blurred vision
Serious (≤1 %)
• Coronary vasospasm, transient ischemic attack (TIA), stroke, myocardial infarction, severe hypertension, pruritus, hypersensitivity reactions, serotonin syndrome, angina.
Rare
• Rhabdomyolysis (rare), peripheral edema, nephrotoxicity, hepatotoxicity.
Monitoring
- Vital signs: BP and heart rate before and during acute migraine treatment, especially in high‑cardiovascular‑risk patients.
- Cardiac: ECG in patients with cardiac history or if chest pain/eggs.
- Liver function: baseline ALT/AST for patients with hepatic disease or on potent CYP1A2 inhibitors.
- Serotonin toxicity: assess for agitation, confusion, hyperthermia if co‑administered with serotonergic drugs.
Clinical Pearls
- Onset Advantage: The nasal spray reaches peak plasma concentration in 30 min.
- Storage Tip: Keep nasal sprays in their original tube and tablets in a cool, dry place; avoid exposure to high temperatures.
--
• Knowledge distilled with up‑to‑date pharmacology insights—use confidently in both academic coursework and clinical practice.