From the Guidelines
Imitrex (sumatriptan) is a vasoconstrictor, not a vasodilator. This medication belongs to the triptan class of drugs and works by narrowing blood vessels in the brain, which helps relieve migraine headaches. Sumatriptan specifically targets serotonin receptors (5-HT1B and 5-HT1D) in cerebral blood vessels, causing them to constrict 1. This vasoconstriction helps counteract the abnormal dilation of blood vessels that occurs during migraine attacks, which is believed to contribute to migraine pain. Because of its vasoconstrictive properties, Imitrex is contraindicated in patients with certain cardiovascular conditions, including coronary artery disease, uncontrolled hypertension, and history of stroke or transient ischemic attack, as noted in the study published in the American Family Physician in 2002 1. Patients should be aware that side effects may include chest tightness, neck pain, or pressure sensations, which are related to its vasoconstrictive effects.
Some key points to consider when prescribing Imitrex include:
- Contraindications: ischemic vascular conditions, vasospastic coronary disease, uncontrolled hypertension, or other significant cardiovascular disease 1
- Dosage: 6 mg subcutaneously, repeated in one hour; maximal dosage, 12 mg per 24 hours; or 25 to 100 mg orally every two hours, maximal dosage: 200 mg per day 1
- Adverse reactions: nausea, warmth, vomiting, vertigo, malaise, headache, injection site reactions, chest pressure and heaviness 1
It is essential to carefully evaluate patients for these conditions before prescribing Imitrex and to monitor them for potential side effects. By understanding the vasoconstrictive properties of Imitrex and its potential risks, healthcare providers can make informed decisions about its use in patients with migraines.
From the FDA Drug Label
Sumatriptan presumably exerts its therapeutic effects in the treatment of migraine headache through agonist effects at the 5-HT1B/1D receptors on intracranial blood vessels and sensory nerves of the trigeminal system, which result in cranial vessel constriction and inhibition of pro-inflammatory neuropeptide release.
Sumatriptan is a vasoconstrictor. 2
From the Research
Imitrex Mechanism of Action
- Imitrex, also known as sumatriptan, is a selective agonist at the vascular 5HT1 receptor, which mediates constriction of certain large cranial blood vessels 3.
- The drug inhibits the release of vasoactive neuropeptides from perivascular trigeminal axons in the dura mater following activation of the trigeminovascular system 3.
- Sumatriptan is thought to relieve migraine attacks by several mechanisms, including cranial vasoconstriction and peripheral and central neural inhibition 4.
Vasoconstrictor Effects
- The evidence suggests that sumatriptan is a vasoconstrictor, as it causes constriction of certain large cranial blood vessels 3, 4.
- This vasoconstrictor effect is likely responsible for the drug's ability to relieve migraine headaches 3, 4.
- However, it is worth noting that sumatriptan's vasoconstrictor effects can also lead to adverse events, such as chest symptoms and myocardial ischemia, in rare cases 3, 5.
Clinical Efficacy
- Sumatriptan has been shown to be effective in relieving migraine headaches, with response rates ranging from 52 to 78% in clinical trials 6.
- The drug is also effective in relieving associated migraine symptoms, such as nausea and photophobia 3, 6.
- Sumatriptan has been compared to other antimigraine treatments, including ergotamine and dihydroergotamine, and has been shown to be similarly effective or more effective in some cases 4, 7.