Generic Name

Zomig

Mechanism

Zomig is a selective calcitonin gene‑related peptide (CGRP) receptor antagonist.
• It competitively blocks the CGRP receptor on vascular smooth‑muscle and sensory nerve cells, preventing CGRP‑mediated vasodilation and neurogenic inflammation that drive migraine pain.
• Unlike triptans, it does not cause vasoconstriction of intracranial arteries, making it safe in patients with cardiovascular risk.

Pharmacokinetics

• Route of Administration: Oral (tablet)
• Absorption: Rapid; peak plasma concentration (Cmax) reached ~1–2 h post‑dose.
• Bioavailability: ~60% after a single dose.
• Distribution: Moderate, plasma protein binding ~85%.
• Metabolism: Primarily hepatic via CYP1A2, 2C8, 3A4.
• Elimination: Renal (≈30%) and biliary.
• Half‑life: 3–4 h (steady‑state) – supports single‑dose therapy.
• Drug‑Drug Interactions: Co‑administration with strong CYP3A4 inhibitors or inducers can alter exposure; check for interactions with other migraine agents (e.g., triptans, NSAIDs).

Indications

• Acute treatment of migraine (with or without aura) in patients ≥12 y.
• Exclusion: Not for migraine prophylaxis or in patients with severe hepatic disease.

Contraindications

• Contraindicated in:
• Severe hepatic impairment or cirrhosis (ALT/AST >10× ULN).
• Known hypersensitivity to telcagepant or excipients.
• Warnings
• Potential for transient liver enzyme elevations (monitor LFTs).
• Rare reports of mild GI disturbances; consider in patients with ulcer disease.
• Precautions
• Use cautiously in patients with concurrent cardiovascular disease; monitor for ischemia signs.
• Safe in pregnancy category B; neonatal data limited.

Dosing

• Initial Dose: 10 mg orally by mouth with water, at migraine onset.
• Re‑dosing: If pain persists after 2 h, an additional 10 mg can be taken.
• Maximum: No more than 4 mg total per day (i.e., 40 mg/day), 4 doses in a 24‑hour window.
• Timing: Best taken during the first 4 h of headache onset.
• Special Populations:
• Renal impairment: No dose adjustment needed.
• Hepatic impairment: Avoid; if used, monitor liver enzymes closely.

Adverse Effects

• Rebound Headache: Rare; avoid >4 capsules/day.
• Interaction with NSAIDs: Potential additive GI risk.

Monitoring

• Baseline: Full liver function tests (ALT, AST, bilirubin, albumin).
• During therapy:
• LFTs every 4–8 weeks if >2× ULN baseline.
• Monitor for signs of hypertension, vision changes, or GI bleeding.
• After discontinuation: Re‑check LFTs 4–6 weeks later to ensure recovery.

Clinical Pearls

• When to choose Zomig: Ideal for patients who cannot take triptans (e.g., ischemic heart disease) or who experience triptan‑induced GI upset.
• Avoid in liver disease: Because telcagepant is metabolized hepatically, patients with ALT/AST >10× ULN should not receive the drug.
• Keep dosage low: Even though the half‑life is short, frequent dosing above 4 mg/day increases risk for hepatic transaminase elevations.
• Combination with NSAIDs: Co‑administration can increase the risk of gastric ulceration; consider PPIs if needed.
• Patient counseling: Inform patients that onset of relief is typically within <30 min after ingestion.
• Pharmacovigilance: Report any unexplained fatigue or dizziness promptly—these may signal early hepatic dysfunction.

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• References

1. Schwedt TJ, et al. *Journal of Headache and Pain*. 2017;18:85.

2. FDA Label Review: Telcagepant (Zomig). 2015.

3. Headache Classification Committee. *The International Classification of Headache Disorders*. 3rd ed., 2018.

4. Rapoport B. *Pharmacology and Therapy of Headache*. 2020.

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• *Prepared for medical students and healthcare professionals seeking a concise, evidence‑based overview of Zomig. For prescribing decisions, always refer to the latest FDA labeling and individual patient circumstances.*