Generic Name

Rizatriptan

Mechanism

Rizatriptan is a selective serotonin (5‑HT₁B/5‑HT₁D) receptor agonist.
• Vasoconstriction of cranial meningeal vessels reduces cerebral blood‑flow mediated pain.
• Inhibition of neuropeptide release (e.g., CGRP, substance P) lowers trigeminovascular activation.
• Modulation of central pain pathways dampens pain transmission in the trigeminal nucleus caudalis.

Pharmacokinetics

Rizatriptan reaches peak plasma concentration in ~1 hour; bioavailability is ~70 %.
• Distribution: moderate volume of distribution; crosses the blood‑brain barrier.
• Metabolism: primarily glucuronidation by UGT1A1, minor CYP3A4 activity.
• Elimination: renal excretion of metabolites; mean half‑life ~2.5–3 h.
• Food effect: high‑fat meals delay absorption by ~30 min but do not change overall exposure.

Indications

Rizatriptan is approved for:
• Acute treatment of migraine (with or without aura) in adults and adolescents (≥12 yrs).
• Short‑term management of cluster headaches (oral dosing).

Contraindications

• Cardiovascular disease: myocardial infarction, unstable angina, significant coronary artery disease.
• Uncontrolled hypertension (SBP ≥ 180 mm Hg or DBP ≥ 110 mm Hg).
• History of cerebrovascular disease (stroke, TIA).
• Known hypersensitivity to triptans or excipients.
• Pregnancy: Category B; use only if benefits outweigh risks.
• Concurrent use of MAO inhibitors or other serotonergic agents—risk of serotonin syndrome.
• Drug interactions: strong CYP3A4 or UGT1A1 inhibitors may elevate serum levels.

Dosing

Rizatriptan (doses in mg):
• Initial dose: 10 mg orally (taken with water).
• Re‑dose: ≤1 h after initial dose if symptoms persist; second dose ≤2 h after first, not to exceed 20 mg total within 24 h.
• Maximum: 20 mg per 24‑hour period.
• Administration: orally, sublingual, or via nasal spray (20 µg per spray; max 6 sprays/24 h).

Adverse Effects

Common (≤10 % incidence):
• Tingling, pruritus, warmth or pressure in chest/face.
• Dizziness, fatigue, dysphonia.

Serious (≤1 % incidence):
• Cardiovascular: chest discomfort, palpitations, severe hypertension.
• Neurological: seizures, visual disturbances.
• Serotonin syndrome: agitation, hyperthermia, clonus.
• Rebound headache (if exceeding recommended daily dose).

Monitoring

• Blood pressure and heart rate before first dose in patients with cardiovascular risk.
• Serum electrolytes only if renal dysfunction is suspected.
• Liver function tests: routine monitoring not required but advised if concomitant hepatotoxic drugs.
• Pregnancy status: document prior to use.
• Patient diary: track headache frequency/response to adjust therapy.

Clinical Pearls

• "Fast‑action rule": Because absorption is rapid, skip meals for 30–45 min after a dose to maximize onset.
• Re‑dose window: Use the second dose only if symptoms persist after the first 30–60 min; avoid exceeding 20 mg/24 h to prevent vasospasm.
• Sublingual advantage: For patients with nausea/vomiting or rapid onset need, the sublingual tablet bypasses first‑pass metabolism.
• Combination therapy: Pair with non‑steroidal anti‑inflammatory drugs (NSAIDs) for synergy but be cautious of gastric ulcer risk.
• Prophylactic use: For frequent migraine sufferers, consider a preventive medication; triptans should not be used more than 2‑3 times per week.

These concise, evidence‑based points provide a quick reference for students and practicing clinicians seeking a structured overview of Rizatriptan.