Memantine (Namenda) is an Alzheimer’s drug that has been used for the treatment of pain and migraine headaches. This drug blocks the NMDA receptor in the brain, which is involved in the processing of pain messages and in other neurological conditions such as epilepsy, stroke and traumatic brain injuries.
NMDA receptor antagonist dizocilpine, or MK801 was a drug with a potential to treat all these conditions, but unfortunately it had serious side effects and after spending hundreds of millions of dollars, Merck stopped its development. It is possible that strong inhibition of the NMDA receptor will always lead to serious side effects. We do have several other milder NMDA inhibitors, besides memantine – dextromethorphan, which is used as a cough suppressant and ketamine.
Memantine, 10 to 20 mg a day was studied in 28 patients with migraines that were not responding to at least two standard medications and was found to be effective. A double-blind, placebo-controlled trial of 10 mg of memantine in 52 patients was also positive. Another double-blind placebo-controlled trial of 60 patients also showed some benefit. A review of case reports and two controlled studies concluded that memantine, 10 to 20 mg a day may be an effective treatment for the prevention of migraines. A study of 40 mg of memantine for chronic tension-type headaches did not show any efficacy, although women seemed to benefit more than men. The only side effects of this relatively high dose (the Alzheimer’s dose is 20 mg) were nausea and dizziness. Overall, memantine tends to be well tolerated, even in the elderly with Alzheimer’s.
I do occasionally prescribe memantine and tend to increase the dose to 20 mg twice a day. I have only a few patients who obtained very good relief and remain on the drug. It is certainly not the first, second, or third drug I prescribe, but when many other drugs fail, it is worth a try since potential side effects are relatively mild.
