The Chronic Pain Team at Kaiser prescribed memantine for me, and it reduced the severe neuropathy in my legs by a whopping 80%—and that has continued for well over a year.
It’s an old drug used to treat Alzheimer’s disease, so it’s well known and inexpensive. I’ve had no side effects. You have to ramp up your dose over one month, and it took that long to be sure it was starting to help, and a total of 6 weeks to be sure.
It fills the same receptors as ketamine—I had to stop taking the little 25-mg ketamine “pills” that you melt under your tongue which I had been using PRN (as needed) for breakthrough pain. (No problem—-memantine worked 24/7 and didn’t make me “spacy” like ketamine did. )
In my Chronic Pain support group two other people tried it. One woman also got good pain relief; another didn’t, but I’m not sure how long she was on it.