Imitrex Injection

— THERAPEUTIC CATEGORIES —
  • Migraine and headache
PAGE CONTENTS
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  • Generic Name & Formulations
  • Indications
  • Dosage and Administration
  • Contraindications
  • Boxed Warnings
  • Warnings/Precautions
  • Pharmacokinetics
  • Interactions
  • Adverse Reactions
  • Clinical Trials
  • Note
  • Patient Counseling

    • Imitrex Injection Generic Name & Formulations

    Legal Class

    Rx

    General Description

    Sumatriptan (as succinate) 4mg/0.5mL, 6mg/0.5mL; for SC inj.

    Pharmacological Class

    Selective 5-HT1B/1D receptor agonist.

    See Also

    How Supplied

    STATdose kit (2 prefilled cartridges + 1 Pen)—1; Refills (2 prefilled cartridges)—1; Single-dose vials (6mg/0.5mL)—5; Tabs—9; Nasal spray (single dose)—6

    How Supplied

    Imitrex Injection is supplied as a clear, colorless to pale yellow, sterile, nonpyrogenic solution as either prefilled syringe and/or autoinjector pen. The needle shield of the prefilled syringe contains dry natural rubber (a latex derivative).

    • Imitrex STATdose System, 4 mg, containing 1 Imitrex STATdose Pen, 2 prefilled single-dose syringe cartridges, and 1 carrying case.

    • Imitrex STATdose System, 6 mg, containing 1 Imitrex STATdose Pen, 2 prefilled single-dose syringe cartridges, and 1 carrying case.

    • Two 4-mg single-dose prefilled syringe cartridges for use with Imitrex STATdose System.

    • Two 6-mg single-dose prefilled syringe cartridges for use with Imitrex STATdose System.

    Storage

    Imitrex Injection – Store between 2° and 30°C (36° and 86°F). Protect from light.

     

    Manufacturer

    GlaxoSmithKline

    Mechanism of Action

    The vascular 5-HT1 receptor subtype to which sumatriptan binds selectively, and through which it presumably exerts its antimigrainous effect, is present on cranial arteries in both dog and primate, on the human basilar artery, and in the vasculature of the isolated dura mater of humans. In these tissues, sumatriptan activates this receptor to cause vasoconstriction, an action in humans correlating with the relief of migraine and cluster headache.

    Imitrex Injection Indications

    Indications

    Acute treatment of migraine or cluster headaches.

    Limitations of Use

    Confirm diagnosis of migraine or cluster headache. Do not use for the prevention of migraine or cluster headache attacks.

    Imitrex Injection Dosage and Administration

    Adult

    ≥18yrs: 6mg SC (may start at lower dose if 6mg not tolerated). Reevaluate if no response. May repeat after 1 hour; max two 6mg doses in 24 hours.

    Children

    <18yrs: not recommended.

    Administration

    • For the autoinjector device (Imitrex STATdose Pen), the needle penetrates approximately 1/4 inch (5 to 6 mm). The injection is intended to be given subcutaneously. Avoid intramuscular or intravascular administration. Instruct patients on the proper use of Imitrex STATdose Pen and direct them to use injection sites with an adequate skin and subcutaneous thickness to accommodate the length of the needle. The needle shield of the prefilled syringe contains dry natural rubber (a latex derivative).

    Imitrex Injection Contraindications

    Contraindications

    Ischemic coronary artery disease (eg, angina pectoris, silent ischemia, history of MI). Coronary artery vasospasm (eg, Prinzmetal's variant angina). Wolff-Parkinson-White Syndrome or arrhythmias associated with other cardiac conduction pathway disorders. Uncontrolled hypertension. History of stroke or transient ischemic attack (TIA). History of basilar or hemiplegic migraine. Peripheral vascular disease. Ischemic bowel disease. Severe hepatic impairment. Within 24 hours of ergot-type drugs (eg, methysergide, dihydroergotamine), or other 5-HT1 agonists. During or within 2 weeks after discontinuing MAO-A inhibitors (MAOI type A).

    Imitrex Injection Boxed Warnings

    Not Applicable

    Imitrex Injection Warnings/Precautions

    Warnings/Precautions

    Confirm diagnosis. Avoid excessive use. Exclude underlying cardiovascular disease, supervise 1st dose, and consider monitoring ECG in patients with likelihood of unrecognized coronary artery disease (eg, postmenopausal women, hypercholesterolemia, men over age 40, hypertension, obesity, diabetes, smokers, strong family history). Monitor cardiovascular function in long-term intermittent use. Peripheral vascular or colonic ischemia following other 5-HT1 agonists. Hepatic or renal dysfunction. Seizure risk. Latex allergy (Inj). Instruct patient on use of autoinjector. Elderly: not recommended. Pregnancy. Nursing mothers (avoid nursing for 12 hours after treatment).

    Warnings/Precautions

    Myocardial Ischemia, Myocardial Infarction, and Prinzmetal Angina

    • Imitrex is contraindicated in patients with ischemic or vasospastic coronary artery disease (CAD). Rare reports of serious cardiac adverse reactions, including acute myocardial infarction, have occurred within a few hours following administration.

    • Prior to treatment, perform a cardiovascular evaluation in triptan-naïve patients who have multiple cardiovascular risk factors (eg, increased age, diabetes, hypertension, smoking, obesity, strong family history of CAD). Do not administer if there is evidence of CAD or coronary artery vasospasm (see Contraindications). For patients with multiple cardiovascular risk factors who have a negative cardiovascular evaluation, consider administering the first Imitrex dose in a medically-supervised setting and performing an electrocardiogram (ECG) immediately following administration and consider periodic cardiovascular evaluation in intermittent long-term users of Imitrex Injection. 

    Arrhythmias

    • Life-threatening disturbances of cardiac rhythm including ventricular tachycardia and ventricular fibrillation leading to death have been reported within a few hours following the administration of 5-HT1 agonists. Discontinue Imitrex if these disturbances occur. 

    • Imitrex is contraindicated in patients with Wolff-Parkinson-White Syndrome or arrhythmias associated with other cardiac accessory conduction pathway disorders.

    Chest, Throat, Neck and Jaw Pain/Tightness/Pressure

    • Perform a cardiac evaluation if patients who are at high cardiac risk experience sensations of tightness, pain, and pressure in the chest, throat, neck, and jaw after treatment with Imitrex. 

    • Imitrex is contraindicated in patients with CAD or Prinzmetal’s variant angina.

    Cerebrovascular Events

    • Cerebral hemorrhage, subarachnoid hemorrhage, and stroke have occurred in patients treated with 5-HT1 agonists, and some have resulted in fatalities. 

    • Exclude other potentially serious neurological conditions before treating headaches in patients not previously diagnosed as migraineurs, and in migraineurs who present with symptoms atypical for migraine. 

    • Discontinue Imitrex if a cerebrovascular event occurs. Imitrex is contraindicated in patients with a history of stroke or transient ischemic attack.

    Other Vasospasm Reactions

    • May cause non-coronary vasospastic reactions, such as peripheral vascular ischemia, gastrointestinal vascular ischemia and infarction (presenting with abdominal pain and bloody diarrhea), splenic infarction, and Raynaud’s syndrome. 

    • Rule out a vasospastic reaction before receiving additional doses of Imitrex in patients who experience symptoms or signs suggestive of a non-coronary vasospastic reaction following the use of any 5-HT1 agonist.

    • Reports of transient and permanent blindness and significant partial vision loss have been reported with the use of 5-HT1 agonists. A causal relationship between visual  disorders and the use of 5-HT1 agonists has not been clearly established. 

    Medication Overuse Headache

    • Overuse of acute migraine drugs (eg, ergotamine, triptans, opioids, or a combination of drugs for 10 or more days per month) may lead to exacerbation of headache (medication overuse headache).

    • Medication overuse headache may present as migraine-like daily headaches or as a marked increase in frequency of migraine attacks. 

    • May be necessary to detoxify patients, including withdrawal of the overused drugs, and treatment of withdrawal symptoms (which often includes a transient worsening of headache). 

    Serotonin Syndrome

    • May occur when Imitrex is coadministered with SSRIs, SNRIs, TCAs, and MAO inhibitors.

    • The onset of symptoms usually rapidly occurs within minutes to hours of receiving a new or a greater dose of a serotonergic medication. 

    • Discontinue if serotonin syndrome is suspected.

    Increase in Blood Pressure

    • Significant elevations in blood pressure, including hypertensive crisis with acute impairment of organ systems, have been reported in patients treated with 5-HT1 agonists including patients without a history of hypertension. 

    • Monitor blood pressure. Imitrex is contraindicated in patients with uncontrolled hypertension.

    Hypersensitivity Reactions

    • Hypersensitivity reactions, including angioedema and anaphylaxis, have occurred which may be life-threatening or fatal.

    • The needle shield of the prefilled syringe contains dry natural rubber (a latex derivative) that has the potential to cause allergic reactions in latex-sensitive individuals.

    Seizures

    • Use caution in patients with a history of epilepsy or conditions associated with a lowered seizure threshold.

    Pregnancy Considerations

    Risk Summary

    • Data from a prospective pregnancy exposure registry and epidemiological studies of pregnant women have not detected an increased frequency of birth defects or a consistent pattern of birth defects among women exposed to sumatriptan compared with the general population. 

    Clinical Considerations

    • Women with migraine may be at increased risk of preeclampsia during pregnancy.

    Nursing Mother Considerations

    Risk Summary

    • There are no data on the effects of sumatriptan on the breastfed infant, or the effects of sumatriptan on milk production. 

    • Consider the developmental and health benefits of breastfeeding along with the mother’s clinical need for Imitrex and any potential adverse effects on the breastfed infant from sumatriptan or from the underlying maternal condition.

    Clinical Considerations

    • Avoid breastfeeding for 12 hours after treatment with Imitrex.

    Pediatric Considerations

    Safety and effectiveness in pediatric patients have not been established. Imitrex is not recommended for use in patients younger than 18 years of age.

    Geriatric Considerations

    • Clinical trials of Imitrex did not include sufficient numbers of patients aged 65 years and older to determine whether they respond differently from younger patients.  In general, use caution with dose selection for an elderly patient, usually starting at the low end of the dosing range.

    • Perform cardiovascular evaluation for geriatric patients who have other cardiovascular risk factors (eg, diabetes, hypertension, smoking, obesity, strong family history of CAD) prior to receiving Imitrex.

    Imitrex Injection Pharmacokinetics

    Absorption

    The bioavailability of sumatriptan via subcutaneous site injection to 18 healthy male subjects was 97% ± 16% of that obtained following intravenous injection.

    Distribution

    Protein binding, determined by equilibrium dialysis over the concentration range of 10 to 1,000 ng/mL is low, approximately 14% to 21%. The effect of sumatriptan on the protein binding of other drugs has not been evaluated.

    Following a 6-mg subcutaneous injection into the deltoid area of the arm in 9 males (mean age: 33 years, mean weight: 77 kg) the volume of distribution central compartment of sumatriptan was 50 ± 8 liters and the distribution half‑life was 15 ± 2 minutes.

    Metabolism

    In vitro studies with human microsomes suggest that sumatriptan is metabolized by MAO, predominantly the A isoenzyme. Most of a radiolabeled dose of sumatriptan excreted in the urine is the major metabolite indole acetic acid (IAA) or the IAA glucuronide, both of which are inactive.

    Elimination

    After a single 6-mg subcutaneous dose, 22% ± 4% was excreted in the urine as unchanged sumatriptan and 38% ± 7% as the IAA metabolite.

    Following a 6-mg subcutaneous injection into the deltoid area of the arm, the systemic clearance of sumatriptan was 1,194 ± 149 mL/min and the terminal half-life was 115 ± 19 minutes.

    Imitrex Injection Interactions

    Interactions

    Ergotamines, other 5-HT1 agonists, MAOIs: see Contraindications. Serotonin syndrome with SSRIs (eg, citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline) or SNRIs (eg, duloxetine, venlafaxine).

    Imitrex Injection Adverse Reactions

    Adverse Reactions

    Tingling, warm/hot sensation, flushing; chest/neck/sinus/jaw discomfort; dizziness/vertigo, muscle pain/weakness, numbness, fatigue, drowsiness, anxiety, sweating, local reactions, seizures, colonic ischemia, drug overuse headache (discontinue if occurs), hypersensitivity reactions; rare: serious cardiac and cerebrovascular events (including fatalities), vision loss. Nasal spray: also dysgeusia, local irritation.

    Imitrex Injection Clinical Trials

    Clinical Trials

    Migraine (Study 1)

    • Study 1 compared 6 different doses of Imitrex Injection (n=30 each group) to placebo (n=62) in a single-attack, parallel-group design. The efficacy outcome was the percentage of patients with relief at 10 minutes, 30 minutes, 1 hour, and 2 hours, defined as the reduction of moderate or severe pain to no or mild pain after dosing without use of rescue medication.

    • Results showed that a greater percentage of patients treated with Imitrex Injection 1mg through 8mg achieved adequate relief compared with placebo:

      • Placebo: 5% at 10min; 15% at 30min; 24% at 1hr; 21% at 2hrs

      • Imitrex 1mg: 10% at 10min; 40% at 30min; 43% at 1hr; 40% at 2hrs

      • Imitrex 2mg: 7% at 10min; 23% at 30min; 57% at 1hr; 43% at 2hrs

      • Imitrex 3mg: 17% at 10min; 47% at 30min; 57% at 1hr; 60% at 2hrs

      • Imitrex 4mg: 13% at 10min; 37% at 30min; 50% at 1hr; 57% at 2hrs

      • Imitrex 6mg: 10% at 10min; 63% at 30min; 73% at 1hr; 70% at 2hrs

      • Imitrex 8mg: 23% at 10min; 57% at 30min; 80% at 1hr; 83% at 2hrs

    Migraine (Study 2 and Study 3)

    • In Studies 2 and 3, Imitrex Injection 6mg was compared with placebo in 1104 patients with moderate or severe migraine pain. Headache relief was defined by a reduction in pain from severe or moderately severe to mild or no headache.

    • 70% of patients treated with Imitrex Injection 6mg achieved headache relief within 1 hour. Approximately 82% and 65% of patients treated with Imitrex 6mg had headache relief and were pain free within 2 hours, respectively.

    • Patients treated with Imitrex experienced relief of photophobia, phonophobia, nausea and vomiting associated with migraine attacks.

    Cluster Headache (Study 4 and Study 5)

    • The efficacy of Imitrex Injection 6mg was evaluated in 2 randomized, double-blind, placebo-controlled, 2-period crossover trials (Studies 4 and 5). Patients were instructed to treat a moderate to very severe headache within 10 minutes of onset. Headache relief was defined by a reduction in headache severity to mild or no pain.

    • In Study 4, a greater proportion of patients treated with Imitrex 6mg achieved pain relief at 5min, 10min, and 15min post-injection compared with those treated with placebo, respectively:

      • For Imitrex 6mg – 21% at 5min; 49% (P <.05) at 10min; 74% (P <.05) at 15min

      • For placebo – 8% at 5min; 10% at 10min; 26% at 15min

    • In Study 5, a greater proportion of patients treated with Imitrex 6mg achieved pain relief at 5min, 10min, and 15min post-injection compared with those treated with placebo, respectively:

      • For Imitrex 6mg – 23% (P <.05) at 5min; 49% (P <.05) at 10min; 75% (P <.05) at 15min

      • For placebo – 7% at 5min; 25% at 10min; 35% at 15min

    Imitrex Injection Note

    Notes

    Register pregnant patients exposed to sumatriptan by calling (800) 336-2176.

    Imitrex Injection Patient Counseling

    Patient Counseling

    Risk of Myocardial Ischemia and/or Infarction, Prinzmetal’s Angina, Other Vasospastic Reactions, and Cerebrovascular Events 

    • Inform patients that Imitrex Injection may cause serious cardiovascular adverse reactions such as myocardial infarction or stroke, which may result in hospitalization and even death. Instruct patients to be alert for the signs and symptoms of chest pain, shortness of breath, weakness, slurring of speech, and instruct them to ask for medical advice when observing any indicative sign or symptoms; serious cardiovascular reactions may occur without warning symptoms. Instruct patients to seek medical advice if they have symptoms of other vasospastic reactions.

    Hypersensitivity Reactions

    • Anaphylactic reactions have occurred in patients receiving Imitrex Injection. Instruct patients to seek immediate medical attention if anaphylactic symptoms develop.

    Concomitant Use with Other Triptans or Ergot Medications

    • Inform patients that use of Imitrex Injeciton within 24 hours of another triptan or an ergot-type medication (eg, dihydroergotamine or methysergide) is contraindicated.

    Serotonin Syndrome

    • Inform patients about the risk of serotonin syndrome with the use of Imitrex Injection or other triptans, particularly during combined use with SSRIs, SNRIs, TCAs, and MAO inhibitors.

    Medication Overuse Headache

    • Inform patients that use of drugs to treat acute migraines for 10 or more days per month may lead to an exacerbation of headache, and encourage patients to record headache frequency and drug use (e.g., by keeping a headache diary). 

    Pregnancy 

    • Advise patients to notify their healthcare provider if they are pregnant or plan to become pregnant.

    Lactation 

    • Advise patients to notify their healthcare provider if they are breastfeeding or plan to breastfeed.

    Ability to Perform Complex Tasks

    • Imitrex Injection may cause somnolence and dizziness. Instruct patients to evaluate their ability to perform complete tasks after administration.

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