IMITREX

Clinical safety rating: caution

Comprehensive clinical and safety monograph for IMITREX (IMITREX).

How it works

Selective serotonin 5-HT1B/1D receptor agonist; causes vasoconstriction of cranial blood vessels and inhibits release of pro-inflammatory neuropeptides.

What the body does with it

Metabolism	Hepatic via monoamine oxidase A (MAO-A) to indole acetic acid metabolite; also minor CYP450 involvement.
Excretion	Primarily renal excretion of unchanged drug and metabolites (approximately 80% of total clearance), with about 20% eliminated in feces via biliary excretion. About 40% of the dose is excreted unchanged in urine.
Half-life	Terminal elimination half-life is approximately 2.5 hours (range 2–3 hours). This short half-life supports its use for acute migraine attacks but may require repeat dosing for prolonged symptoms.
Protein binding	Approximately 14–21% bound to plasma proteins (mainly albumin).
Volume of Distribution	Volume of distribution is approximately 2.4 L/kg (range 1.8–3.2 L/kg). This large Vd indicates extensive tissue distribution, including penetration into the central nervous system.
Bioavailability	Oral: approximately 15% (due to extensive first-pass metabolism); subcutaneous: 97% (nearly complete); intranasal: approximately 17% (range 11–24%).
Onset of Action	Oral: 30–60 minutes; subcutaneous: 10–15 minutes; intranasal: 15–30 minutes. Onset is fastest with subcutaneous administration due to rapid absorption.
Duration of Action	Clinical effect lasts approximately 4–6 hours for a single dose. Pain relief may persist up to 24 hours in some patients, but recurrence of headache is common, often requiring a second dose after 2 hours.

Classification & Brands

Dosing & administration

50 mg to 100 mg orally at onset of migraine; may repeat after 2 hours if needed, max 200 mg/day. Alternatively, 6 mg subcutaneously once, may repeat after 1 hour, max 12 mg/day. Intranasal: 5 mg to 20 mg in one nostril at onset; may repeat after 2 hours, max 40 mg/day.

Dosage form	TABLET
Renal impairment	No dose adjustment needed for mild to moderate renal impairment. Hemodialysis: Avoid use; no data.
Liver impairment	Contraindicated in severe hepatic impairment (Child-Pugh C). For mild to moderate impairment, caution with oral; subcutaneous dose unchanged. No specific dose reductions defined.
Pediatric use	Adolescents ≥12 years: 50 mg orally at onset; may repeat after 2 hours (max 100 mg/day). Subcutaneous: 3 mg to 6 mg once; may repeat after 1 hour (max 12 mg/day). Not recommended under 12 years.
Geriatric use	Lower starting doses recommended due to increased risk of adverse events (e.g., coronary artery disease). No specific dose adjustments defined; use with caution.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for IMITREX (IMITREX).

Breastfeeding	Sumatriptan is excreted into breast milk in low amounts; infant relative dose is approximately 3-15% of maternal weight-adjusted dose. M/P ratio not established. Caution advised; monitor infant for adverse effects such as diarrhea or vomiting.
Teratogenic Risk	Pregnancy Category C. First trimester: Limited human data; animal studies show embryotoxicity and increased resorptions at maternal toxic doses. Second/third trimester: No well-controlled studies; potential for uterine hypertonus and reduced placental perfusion. Avoid use in pregnancy unless benefit outweighs risk.

Warnings & precautions

■ FDA Black Box Warning

Not recommended for use in patients with history of coronary artery disease, myocardial infarction, or uncontrolled hypertension due to risk of coronary vasospasm.

Side Effect Profile

Serious Effects

Absolute Contraindications

["History of ischemic heart disease or coronary artery vasospasm","Uncontrolled hypertension","Hemiplegic or basilar migraine","Concurrent MAO-A inhibitor use or within 2 weeks","Severe hepatic impairment"]

Clinical Precautions

Precautions

["Risk of myocardial ischemia, infarct, and vasospasm","Serotonin syndrome risk with SSRIs/SNRIs","Rebound headache with overuse","Not for hemiplegic or basilar migraine","Avoid within 24 hours of ergotamine or another triptan"]

Clinical Tips & Counseling

Drug interactions

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IMITREX

Clinical safety rating: caution

Comprehensive clinical and safety monograph for IMITREX (IMITREX).

How it works

Selective serotonin 5-HT1B/1D receptor agonist; causes vasoconstriction of cranial blood vessels and inhibits release of pro-inflammatory neuropeptides.

What the body does with it

Metabolism	Hepatic via monoamine oxidase A (MAO-A) to indole acetic acid metabolite; also minor CYP450 involvement.
Excretion	Primarily renal excretion of unchanged drug and metabolites (approximately 80% of total clearance), with about 20% eliminated in feces via biliary excretion. About 40% of the dose is excreted unchanged in urine.
Half-life	Terminal elimination half-life is approximately 2.5 hours (range 2–3 hours). This short half-life supports its use for acute migraine attacks but may require repeat dosing for prolonged symptoms.
Protein binding	Approximately 14–21% bound to plasma proteins (mainly albumin).
Volume of Distribution	Volume of distribution is approximately 2.4 L/kg (range 1.8–3.2 L/kg). This large Vd indicates extensive tissue distribution, including penetration into the central nervous system.
Bioavailability	Oral: approximately 15% (due to extensive first-pass metabolism); subcutaneous: 97% (nearly complete); intranasal: approximately 17% (range 11–24%).
Onset of Action	Oral: 30–60 minutes; subcutaneous: 10–15 minutes; intranasal: 15–30 minutes. Onset is fastest with subcutaneous administration due to rapid absorption.
Duration of Action	Clinical effect lasts approximately 4–6 hours for a single dose. Pain relief may persist up to 24 hours in some patients, but recurrence of headache is common, often requiring a second dose after 2 hours.

Classification & Brands

Dosing & administration

Dosage form	TABLET
Renal impairment	No dose adjustment needed for mild to moderate renal impairment. Hemodialysis: Avoid use; no data.
Liver impairment	Contraindicated in severe hepatic impairment (Child-Pugh C). For mild to moderate impairment, caution with oral; subcutaneous dose unchanged. No specific dose reductions defined.
Pediatric use	Adolescents ≥12 years: 50 mg orally at onset; may repeat after 2 hours (max 100 mg/day). Subcutaneous: 3 mg to 6 mg once; may repeat after 1 hour (max 12 mg/day). Not recommended under 12 years.
Geriatric use	Lower starting doses recommended due to increased risk of adverse events (e.g., coronary artery disease). No specific dose adjustments defined; use with caution.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for IMITREX (IMITREX).

Breastfeeding	Sumatriptan is excreted into breast milk in low amounts; infant relative dose is approximately 3-15% of maternal weight-adjusted dose. M/P ratio not established. Caution advised; monitor infant for adverse effects such as diarrhea or vomiting.
Teratogenic Risk	Pregnancy Category C. First trimester: Limited human data; animal studies show embryotoxicity and increased resorptions at maternal toxic doses. Second/third trimester: No well-controlled studies; potential for uterine hypertonus and reduced placental perfusion. Avoid use in pregnancy unless benefit outweighs risk.

Warnings & precautions

■ FDA Black Box Warning

Not recommended for use in patients with history of coronary artery disease, myocardial infarction, or uncontrolled hypertension due to risk of coronary vasospasm.