According to the National Headache Foundation, about 30 million Americans suffer from migraine headaches. Sumatriptan, a prescription drug sold under the brand name Imitrex, was the first in a class of drugs called triptans that are used to treat migraines. Sumatriptan is available as an injectable, nasal spray and tablet.
The Migraine Process
Migraines begin with the nerves that surround arteries in the brain. Before a migraine, these nerves release a neurotransmitter called calcitonin gene-related peptide, or CGRP. This neurotransmitter causes the arteries to expand, or dilate. When arteries dilate, fluids and proteins leak out of the arteries into the surrounding tissues. This causes swelling in the tissues and triggers pain signals in the brain.
Function of Sumatriptan
Sumatriptan has a chemical structure similar to the neurotransmitter serotonin. In the body, Sumatriptan acts as a serotonin agonist. This means it mimics the action of serotonin. In the brain, serotonin prevents the release of the neurotransmitter CGRP. Serotonin also causes arteries in the brain to constrict, or narrow.
Side Effects
In most people, sumatriptan works better against migraines than ergot alkaloids such as dihydroergotamine (Migranal) and ergotamine mixtures such as Cafergot. Common side effects of sumatriptan include tingling, dizziness and chest pain. Because sumatriptan can also narrow the coronary arteries, it shouldn't be used by people with heart problems.
Dosage
The effects of sumatriptan may wear off before the migraine has abated, so many people need to take more than one dose over the course of the migraine.
The dosage for the oral form of sumatriptan is 25mg to 100mg at the onset of the headache, with a maximum of 200mg per day. For sumatriptan nasal spray, the dose is 5mg to 20mg at the onset of the headache, with a maximum daily dose of 40mg. The dosage for injectable sumatriptan is 6mg injected under the skin (subcutaneously). Another 6mg injection may be repeated two hours later, but no more than two injections can be given in a 24-hour period.
References
- Basic and Clinical Pharmacology; Bertram Katzung; 2007
- Imitrex Nasal Spray Prescribing Information
- Imitrex Injection Prescribing Information
