The exact mechanisms that occur to cause a migraine headache are not fully understood. Migraine headaches occur after acute constriction and then relaxation and dilation of blood vessels in the brain. Several neurochemicals are involved in the development of migraines and treatments often include medications that cause vasoconstriction, to restore normal blood vessel tone. These medications often have side effects that make them dangerous for some patients, especially those with heart disease or circulatory problems, where constriction of blood vessels can lead to blockage of an artery.
Preventive therapy may be needed if patients have frequent attacks, severe symptoms that disrupt their lives, or attacks that last a long time. Preventive therapy may include blood pressure medications (propranolol), seizure medications (divalproex, gabapentin) or antidepressants (nortriptyline).
A new class of medications is now available and may offer relief for patients who have not had success with other preventive therapies. These new drugs are called calcitonin gene-related peptide (CGRP) inhibitors. These drugs block the action of CGRP which is a neurochemical involved in the initial constriction of the blood vessels in the brain that occurs before the migraine starts.
By using a medication that specifically targets migraine pathophysiology, side effects are fewer than what we see with some of the other preventive medications. We can also expect fewer drug interactions since these drugs are monoclonal antibodies (complex proteins) that are broken down via different pathways than traditional drugs which are less complex molecules.
There are CGRP inhibitors currently available: erenumab (Aimovig), fremanezumab (Ajovy), and galcanezumab (Emgality). These drugs are given as monthly injections.
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