Zomig - Drug Monograph

Introduction

Zomig (zolmitriptan) is a selective serotonin 5-HT₁B/1D receptor agonist ("triptan") indicated for the acute treatment of migraine attacks with or without aura in adults. It is one of seven triptans available in the United States and is distinguished by multiple routes of administration (oral tablet, orally disintegrating tablet, and nasal spray) and a relatively short half-life. Zomig is widely used in clinical practice as a first-line abortive therapy for moderate-to-severe migraine attacks that do not respond adequately to simple analgesics.

Drug Class and Overview

• Class: Selective 5-HT₁B/1D receptor agonist; second-generation triptan.
• Related agents: Sumatriptan, rizatriptan, naratriptan, almotriptan, eletriptan, frovatriptan.
• Distinguishing features:
• Available in oral, orally disintegrating (ZMT), and intranasal formulations.
• Active metabolite (N-desmethyl-zolmitriptan) is also a 5-HT₁B/1D agonist with greater potency at the receptor.
• Hepatic metabolism primarily via CYP1A2, with secondary contribution from MAO-A.
• Onset of action: ~30 minutes (oral); ~10–15 minutes (nasal spray).

Mechanism of Action

Zolmitriptan binds with high affinity to serotonin 5-HT₁B and 5-HT₁D receptors located on intracranial blood vessels and trigeminal nerve terminals. Activation of 5-HT₁B receptors produces vasoconstriction of dilated cranial extracerebral vessels, while activation of 5-HT₁D receptors inhibits the release of pro-inflammatory neuropeptides (such as calcitonin gene-related peptide [CGRP] and substance P) from perivascular trigeminal sensory neurons. Together, these actions reverse the vasodilation and neurogenic inflammation thought to underlie migraine pain. The drug does not possess analgesic activity in non-migraine pain models and is not effective for migraine prophylaxis.

Indications

• Acute treatment of migraine with aura in adults.
• Acute treatment of migraine without aura in adults.
• Not indicated for the prevention of migraine, the treatment of cluster headache, or the treatment of hemiplegic or basilar migraine.

Dosage and Administration

Adults (≥18 years):

• Oral tablet: Initial dose 1.25 mg or 2.5 mg; may repeat after 2 hours if response is inadequate. Maximum single dose 5 mg; maximum daily dose 10 mg.
• Orally disintegrating tablet (ZMT): Same dosing as oral tablet; place on tongue and allow to dissolve.
• Nasal spray: 2.5 mg or 5 mg single dose into one nostril; may repeat after 2 hours. Maximum 10 mg/day.

Renal impairment: No dose adjustment generally required; use caution in severe impairment (limited data). Hepatic impairment: Use with caution in moderate-to-severe hepatic impairment; consider lower initial dose (1.25 mg). Pediatric patients: Not established for children <18 years (safety and efficacy not demonstrated). Geriatric patients: Use cautiously; efficacy and safety in patients >65 years not well studied. Pregnancy: Category C; use only if potential benefit justifies potential risk.

Pharmacokinetics

• Absorption: Rapidly absorbed after oral administration; bioavailability ~40%. Onset of action ~30–60 minutes (oral); ~10–15 minutes (nasal).
• Distribution: Protein binding ~25%; volume of distribution ~7 L/kg; crosses the blood-brain barrier.
• Metabolism: Hepatic; converted to N-desmethyl-zolmitriptan (active, 2–6× more potent) via CYP1A2, with secondary metabolism by MAO-A. Both parent and metabolite contribute to clinical effect.
• Elimination: Renal excretion (~65%) and fecal (~30%); mean total clearance ~25 mL/min/kg.
• Half-life: Approximately 3 hours for zolmitriptan and its active metabolite.

Contraindications

• Ischemic heart disease (angina pectoris, history of myocardial infarction, documented silent ischemia).
• Coronary artery vasospasm (Prinzmetal angina) or other significant underlying cardiovascular disease.
• Uncontrolled hypertension.
• Concurrent use (within 24 hours) with another 5-HT₁ agonist (e.g., another triptan) or ergotamine-containing/ergot-type medications (e.g., dihydroergotamine, methysergide).
• Concurrent use with MAO-A inhibitors or within 2 weeks of discontinuing MAO-A inhibitors.
• Known hypersensitivity to zolmitriptan or any component of the formulation.
• Hemiplegic or basilar migraine (lack of safety data).

Warnings and Precautions

• Cardiovascular risk: Triptans can cause coronary vasospasm; not recommended in patients with multiple cardiovascular risk factors unless a cardiovascular evaluation provides reassurance.
• Cerebrovascular events: Rare reports of stroke, subarachnoid hemorrhage, and intracerebral hemorrhage; discontinue if suspected.
• Serotonin syndrome: Risk when used concomitantly with SSRIs, SNRIs, TCAs, MAO inhibitors, or other serotonergic drugs; monitor for agitation, hyperreflexia, clonus, hyperthermia.
• Medication overuse headache: Risk with frequent use (>10 days/month); limit use to ≤2–3 days per week.
• Hypertension: May increase blood pressure; caution in controlled hypertension.
• Seizures: Use cautiously in patients with a history of seizures.
• Pregnancy and lactation: Use only if clearly needed; excreted in breast milk.

Drug Interactions

• MAO-A inhibitors (e.g., phenelzine, tranylcypromine): Contraindicated; markedly increase zolmitriptan exposure.
• CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin): May increase zolmitriptan plasma concentrations; consider dose reduction.
• Ergot alkaloids (e.g., ergotamine, dihydroergotamine): Additive vasospasm risk; do not use within 24 hours of each other.
• Other triptans: Additive 5-HT agonist effects; do not use within 24 hours.
• SSRIs/SNRIs (e.g., fluoxetine, sertraline, venlafaxine): Increased risk of serotonin syndrome; use lowest effective doses and monitor.
• Propranolol: Increases zolmitriptan AUC by ~50%; consider lower initial dose.

Adverse Effects

Common (≥5%):

• Dizziness, paresthesia, somnolence, asthenia, nausea, dry mouth.
• Nasal spray: unusual taste, paresthesia of throat/nose, local irritation.

Serious/rare:

• Coronary vasospasm, myocardial infarction, ventricular arrhythmia.
• Stroke, subarachnoid hemorrhage.
• Serotonin syndrome.
• Anaphylaxis, angioedema.
• Medication overuse headache with frequent dosing.

Monitoring Parameters

• Cardiovascular: Baseline assessment of cardiac risk factors; periodic re-evaluation in patients with new or changing risk factors.
• Blood pressure: Especially in patients with hypertension.
• Headache frequency: Monitor for medication overuse headache (use >10 days/month).
• Signs of serotonin syndrome: When used with serotonergic agents.
• Renal/hepatic function: Consider in patients with severe impairment.

Patient Education

• Take at the first sign of migraine pain; not effective if taken during the aura alone.
• Do not use more than the prescribed dose; allow at least 2 hours between doses.
• Do not use more than 2–3 days per week to avoid medication overuse headache.
• Inform your clinician of any history of heart disease, stroke, hypertension, or seizures.
• Avoid concurrent use with ergot medications, other triptans, or MAO inhibitors.
• Seek emergency care for chest pain, tightness, severe dizziness, shortness of breath, or sudden severe headache different from prior migraines.
• Report symptoms of serotonin syndrome (agitation, tremor, fever, diarrhea) especially if taking antidepressants.
• Pregnancy and breastfeeding: discuss risks with your clinician.

Clinical Pearls

1. Triptans are most effective when taken early in the migraine attack, while pain is still mild—delaying treatment reduces efficacy.
2. Zolmitriptan is one of the few triptans available as a nasal spray, useful in patients with significant nausea/vomiting who cannot retain oral medications.
3. The active metabolite (N-desmethyl-zolmitriptan) is more potent than the parent drug, contributing to clinical effect and prolonging duration of action.
4. CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin) can significantly increase zolmitriptan exposure—consider dose reduction.
5. Triptans are contraindicated in patients with coronary artery disease due to risk of coronary vasospasm; obtain cardiovascular evaluation in patients with multiple risk factors before prescribing.
6. Combining triptans with SSRIs/SNRIs is common in practice but carries a small risk of serotonin syndrome—educate patients on warning symptoms.

References

1. AstraZeneca. Zomig (zolmitriptan) Prescribing Information. U.S. Food and Drug Administration.
2. American Headache Society. The American Headache Society Position Statement on Integrating New Migraine Treatments into Clinical Practice. Headache. 2019.
3. Ferrari MD, Goadsby PJ, Rami A, et al. Triptans (serotonin, 5-HT₁B/1D agonists) in migraine: detailed results and conclusions of a meta-analysis of 53 trials. Cephalalgia. 2002.
4. Dodick DW. Triptans and CNS side effects: a review. Headache. 2004.
5. Goodman & Gilman's The Pharmacological Basis of Therapeutics. 14th ed. McGraw-Hill Education.
6. Katzung BG, Trevor AJ. Basic and Clinical Pharmacology. 15th ed. McGraw-Hill Education.
7. International Headache Society. The International Classification of Headache Disorders, 3rd edition (ICHD-3). Cephalalgia. 2018.
8. World Health Organization. Model List of Essential Medicines. WHO.
9. Bigal ME, Lipton RB. The preventive treatment of migraine. N Engl J Med. 2007.
10. Tfelt-Hansen P. Efficacy and adverse events of subcutaneous, oral, and intranasal sumatriptan used for migraine treatment: a systematic review based on number needed to treat. Cephalalgia. 1998.