Antidepressants
The type of antidepressants that I normally prescribe for migraine prevention are the tricyclic antidepressants . The one that has the best data in the literature and is often prescribed is amitriptyline (Elavil); I prefer a cousin to this medicine, nortriptyline. I prescribe tricyclics because many of my migraine patients have 2 other comorbid problems: depression and trouble staying asleep at night. Amitriptyline tends to cause drowsiness and can help patients sleep. It can also cause dry mouth, trouble urinating (especially in men), constipation, weight gain, and can slow patients down mentally, so it should not be prescribed to elderly patients. These antidepressants should be prescribed in very low doses and taken an hour before bedtime. The dose should be increased gradually over several weeks to help reduce adverse events. The best dose for migraine is often lower than the antidepressant dose, so sometimes a depressed patient needs 2 types of antidepressants. The typical dose for migraine prevention is about 50 to 75 mg. For depression, it is about 150 mg.
The patient would then need to increase their dose gradually for a month and remain on the target dose for at least another month. At the end of 2 months, they would have some idea whether it was working for them. If it was not, I might increase the dose even further. It is important to set expectations with patients at the beginning of treatment and tell them it is going to take 2 to 3 months to see if it works. If it does not work, I tell them, we will have to try another one, and that is going to take 2 or 3 months as well, until we can switch to the newer medications, which start to work in the first month, often in the first few days.
Why wouldn’t we just start with the newer preventives? Insurance companies require patients to fail, on average, 2 categories of the older medications before they will pay for the newer ones. Medicare usually only covers the older generic medications.
New migraine preventive medications
Monoclonal Antibodies
mAbs that block CGRP for the prevention of migraine, such as erenumab, fremanezumab, galcanezumab, and eptinezumab, target either the CGRP ligand itself or block the receptor to CGRP. This class of medication became available about 5 years ago. The first one approved was erenumab (Aimovig). It was tried by a lot of headache specialists, many neurologists, and then some general physicians once it came to market. It is the only one in its class that grabs the ligand CGRP and prevents it from docking on its receptor. Recently, 5-year safety data indicated it is extremely safe with only a few side effects , (it has been shown to cause some constipation and hypertension). It does, however, tend to lower the number of migraine days per month by about 40% to 50%. At the beginning of erenumab’s availability , researchers took patients that had 8 to 22 days of migraine per month and put them in double-blind, placebo-controlled, randomized trials. They found that some patients' migraine days went down gradually to 10 to 12 days from 20 migraine days per month. Erenumab works quickly, and most patients improve within 2 weeks.