Imitrex

Im·i·trex (m-trks)

A trademark for the drug sumatriptan and its succinate form.

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sumatriptan succinate

Imigran (UK), Imitrex

Pharmacologic class: Selective 5-hydroxytryptamine₁ (5-HT₁) agonist

Therapeutic class: Vascular headache suppressant

Pregnancy risk category C

Action

Selectively activates vascular 5-HT₁ receptor sites, causing vasoconstriction in intracranial arteries

Availability

Injection: 6 mg/0.5-ml prefilled syringes, 0.6 mg/0.5-ml vials, SELF dose injection kit (containing two prefilled syringes)

Nasal spray: 5 mg in 100-mcl unit dose spray device (package of six), 20 mg in 100-mcl unit dose spray device (package of six)

Tablets: 25 mg, 50 mg, 100 mg

⊘Indications and dosages

➣ Acute migraine

Adults: Initially, 25 mg P.O.; if response inadequate after 2 hours, may give up to 100 mg P.O. If migraine recurs, repeat dose q 2 hours, not to exceed 200 mg/day. Or 6 mg subcutaneously, repeated as needed after 1 hour, not to exceed 12 mg in 24 hours. If P.O. therapy will follow subcutaneous injection, additional P.O. sumatriptan may be given q 2 hours, not to exceed 100 mg/day. Or a single dose of 5, 10, or 20 mg intranasally in one nostril, repeated p.r.n. in 2 hours, not to exceed 40 mg in 24 hours.

Dosage adjustment

• Hepatic impairment

Contraindications

• Hypersensitivity to drug
• Hemiplegic or basilar migraine headache
• Ischemic cardiac, cerebrovascular, or peripheral vascular disease (such as a history of myocardial infarction, stroke, angina, or ischemic bowel)
• Uncontrolled hypertension
• Severe hepatic impairment
• MAO inhibitor use within past 14 days
• Use of other 5-HT₁ agonists, ergotamine-containing drugs, or ergot-type products within past 24 hours

Precautions

Use cautiously in:
• patients with cardiovascular risk factors (hypertension, hypercholesterolemia, smoking, obesity, diabetes, amily history of cardiovascular disease, men over age 40, menopausal women)
• elderly patients
• women of childbearing age
• pregnant or breastfeeding patients
• children younger than age 18 (safety not established).

Administration

☞ If patient has risk factors for coronary artery disease, know that first dose should be given in medical setting with emergency equipment at hand.
☞ Don't give within 14 days of MAO inhibitors.
☞ Don't administer within 24 hours of other 5-HT₁ agonists, ergotamine-containing drugs, or ergot-type products.

Route	Onset	Peak	Duration
P.O.	Within 30 min	2-2.5 hr	Unknown
Subcut.	10-20 min	Unknown	Unknown
Intranasal	Unknown	Unknown	Unknown

Adverse reactions

CNS: headache, malaise, dizziness, drowsiness, fatigue, vertigo, anxiety, tight feeling in head, numbness

CV: angina, chest pressure or tightness, transient hypertension, ECG changes, coronary vasospasm, myocardial infarction

EENT: vision changes, nasal sinus discomfort, throat discomfort

GI: abdominal discomfort, dysphagia

Musculoskeletal: jaw discomfort, muscle cramps, myalgia, neck pain or stiffness

Skin: flushing; tingling; warm, cool or, burning sensation

Other: injection site reaction, feeling of heaviness or tightness

Interactions

Drug-drug. Dihydroergotamine, ergotamine, methysergide: increased risk of vasospastic reaction

Lithium, MAO inhibitors, selective serotonin reuptake inhibitors: weakness, hyperreflexia, incoordination

Drug-herbs. Horehound: enhanced serotonergic effects

Patient monitoring

☞ Monitor cardiovascular status closely. Be aware that drug may cause serious and possibly fatal cardiac disorders.
• Watch for neurologic and vision changes. Institute safety measures as needed to prevent injury.
• Monitor patient's response to drug. Assess need for repeat doses.
• Watch for injection site reaction, which should subside within 1 hour.

Patient teaching

• Instruct patient to take as soon as possible after migraine onset.
☞ Teach patient to recognize and immediately report serious cardiovascular reactions.
• Explain proper drug use. Stress that drug is effective only in treating diagnosed migraine, not other headache types. Tell patient it doesn't prevent migraine.
• With subcutaneous use, instruct patient to inject dose using spring-loaded injector system included in package. If headache recurs after dose, tell him he may take a second dose, but should wait at least 1 hour after initial dose and shouldn't exceed two 6-mg injections in a 24-hour period. Instruct him to report injection site reaction that doesn't subside within 1 hour.
• With oral use, tell patient he may take a second dose 2 hours after first dose if migraine recurs. Tell him he may repeat oral doses every 2 hours as needed, up to 200 mg in a 24-hour period.
• With intranasal use, tell patient to spray 5, 10, or 20 mg into one nostril, as prescribed. Tell him he may repeat dose after 2 hours but shouldn't exceed 40 mg in a 24-hour period.
• Advise patient not to use drug for more than four episodes per month.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and herbs mentioned above.