For a first or second-line therapy, common drugs of choice include verapamil (Calan) and the tricyclic antidepressant nortriptyline (Pamelor). For verapamil, “We use it in a very low dosage, below levels that we would use for blood pressure control,” said Aaron Benson, MD, clinical adjunct professor of otolaryngology head and neck surgery at the University of Michigan and Michigan State University. “I find that to be very effective in my patients and it has the lowest side effect profile of the medications that I can normally offer to patients,” said Dr. Benson, also medical director of the Ohio Hearing and Balance Institute at St. Luke’s Hospital in Maumee.
Explore This IssueJune 2011
Dr. Foster agreed, noting that verapamil is a good choice for patients with hypertension or arrhythmias. How the drug works is less clear, especially in light of the uncertain etiology of migraines. One hypothesis suggests symptoms may be related to a vasospasm of the blood supply to the posterior fossa. Another posited that the condition results from a disruption of calcium ion channels. Either way, Dr. Benson said calcium channel blockers make sense as a first-line therapy. “A calcium channel blocker relaxes vessels so it would work if it’s vasospasm, and if it’s a calcium ion channel problem, well, it’s a calcium channel blocker,” he said. “I find that to be an extremely effective medication.”
Dr. Goebel often starts with the relatively inexpensive nortriptyline, which he prefers over its chemical cousin amitriptyline (Elavil) because it is less sedating and patients aren’t as likely to gain weight. Dr. Foster noted that amitriptyline’s sedative effect can be a plus for patients with poor sleep patterns, thereby also removing lack of sleep as a potential migraine trigger. Other side effects can include dry eyes and a dry mouth, and both drugs are usually contraindicated for pregnant women.
The potential mechanism for action by tricyclic antidepressants in addressing migraine is poorly understood, though some researchers suggest that regulation of the serotonin neurotransmitter may play a role. Experts also note that antidepressants have been widely used for pain control.
Among the few promising new drugs, Dr. Foster pointed to Namenda (memantine), normally used to treat Alzheimer’s disease. The drug seems to work best in cases with prominent aura, she said, when the inner ear may be damaged by low blood flow, by blocking the NMDA [N-methyl-D-aspartate] receptor calcium channel. That channel is involved in excitotoxicity, or the death of nerve cells from excessive stimulation, a pathway that Dr. Foster has been exploring as the mechanism for severe attacks. “If you can block excitotoxicity, you can block the damage,” she said. “So for people with progressive damaging disorders who have migraine, blocking that kind of damage then prevents the disorder from progressing.”