What is the recommended dosing for Imitrex (sumatriptan) in a patient with migraine symptoms, considering their medical history and potential contraindications such as cardiovascular disease, hypertension, and impaired renal or liver function?

Imitrex (Sumatriptan) Dosing for Migraine

Standard Dosing Regimens

The recommended starting dose of oral sumatriptan is 50 mg or 100 mg at migraine onset, with the option to repeat once after 2 hours if needed, not exceeding 200 mg in 24 hours. 1

Oral Dosing Options

• 50-100 mg oral tablets: Take at onset of migraine headache (not during aura phase). The 50 mg and 100 mg doses provide greater effect than 25 mg, though 100 mg may not provide substantially greater benefit than 50 mg 1
• Second dose: If headache persists or returns after initial improvement, repeat the same dose after at least 2 hours 1
• Maximum daily dose: 200 mg in 24 hours 2, 1
• 25 mg dose: Reserved for patients requiring lower doses due to tolerability concerns or those who respond adequately to this strength 2, 3

Subcutaneous Dosing

• 6 mg subcutaneous injection: Most effective route with 59-70% achieving complete pain relief by 2 hours, with onset within 15 minutes 2, 4, 5
• Repeat dosing: May repeat once after 1 hour if needed 2
• Maximum daily dose: 12 mg in 24 hours 2
• Best for: Patients with rapid progression to peak intensity, severe nausea/vomiting, or inadequate response to oral formulations 4

Intranasal Dosing

• 5-20 mg (one to two sprays) in one nostril: Alternative for patients with significant nausea 2, 4
• Repeat dosing: May repeat after 2 hours 2
• Maximum daily dose: 40 mg per day 2

Critical Frequency Limitation

Limit sumatriptan use to no more than 2 days per week (approximately 8-9 treatment days per month) to prevent medication-overuse headache. 2, 4, 6

• Using triptans more than twice weekly transforms episodic migraine into chronic daily headache 4, 6
• Maximum safe prescription: 18 tablets per month (9 treatment days × 2 tablets per attack) 6
• The FDA states that safety of treating more than 4 headaches in a 30-day period has not been established 1

Dosing Modifications for Special Populations

Hepatic Impairment

• Maximum single dose: 50 mg in patients with mild to moderate hepatic impairment 2, 1
• Sumatriptan is contraindicated in severe hepatic impairment 2

Cardiovascular Disease

Sumatriptan is absolutely contraindicated in patients with:

• Coronary artery disease or history of myocardial infarction 2, 5
• Prinzmetal (variant) angina 5
• Uncontrolled hypertension 2, 5
• Hemiplegic or basilar migraine 2
• Cerebrovascular disease or previous stroke 4

Renal Impairment

• No specific dose adjustment required for renal impairment, though dihydroergotamine (an alternative) is contraindicated in renal impairment 2

Drug Interactions and Contraindications

Do not use sumatriptan within 24 hours of:

• Ergotamine derivatives or dihydroergotamine 2
• Other triptans 2

Do not use sumatriptan within 14 days of:

• MAOIs (monoamine oxidase inhibitors) 2

Use with caution when combined with:

• SSRIs (selective serotonin reuptake inhibitors) - increased risk of serotonin syndrome 2
• Propranolol or other beta-blockers 2

Efficacy Expectations

• 2-hour headache relief: 52-57% with oral sumatriptan vs 17-26% with placebo 7, 3, 8
• 4-hour headache relief: 65-78% with oral sumatriptan vs 19-38% with placebo 3, 8
• Headache recurrence: Approximately 40% of initial responders experience recurrence within 24 hours, effectively treated with a second dose 5
• Number needed to treat (NNT): 3.4 for 100 mg dose, 3.2 for 50 mg dose at 2 hours 7

Common Adverse Events

• Oral formulation: Nausea, warmth, vomiting, vertigo, malaise, headache, chest pressure and heaviness 2
• Subcutaneous formulation: Injection site reactions (30%), chest symptoms (3-5%), nausea, warmth 2, 5
• Number needed to harm (NNH): 7.1 for 100 mg dose (minor adverse events) 7

Clinical Decision Algorithm

1. Start with 50-100 mg oral for most patients with moderate to severe migraine 1, 3
2. Switch to subcutaneous 6 mg if oral route fails after 2-3 migraine episodes, or if rapid onset needed 4, 9
3. Try different triptan if sumatriptan fails after adequate trial, as failure of one triptan does not predict failure of others 4
4. Add NSAID (naproxen 500 mg) to triptan for superior efficacy compared to either agent alone 4
5. Initiate preventive therapy immediately if requiring acute treatment more than twice weekly 2, 4

Critical Pitfalls to Avoid

• Never administer during aura phase - wait until headache begins 5
• Never exceed frequency limits - this creates medication-overuse headache requiring withdrawal and preventive therapy 2, 4, 6
• Never combine with ergotamines within 24 hours due to additive vasoconstrictive effects 2
• Never use in pregnancy - sumatriptan is contraindicated 2
• Screen cardiovascular risk before first dose in patients over 40, with multiple cardiac risk factors, or known vascular disease 2, 4