Namenda (memantine) is a well established, treatment for moderate to severe Alzheimer’s Disease. Namenda acts to reduce the activity of a set of receptors in the brain and spinal cord called NMDA receptors.
Overstimulation of NMDA receptors is believed to contribute to the increased pain sensitivity in Fibromyalgia. Therefore, treating Fibromyalgia patients with memantine should, in theory, decrease Fibromyalgia pain.
But, for the last decade no one was willing to invest the funds needed to put this theory to the test. But, now that has changed. A very capable Spanish research team has done a double-blind study. The results: Fibromyalgia patients treated with memantine had less pain, better cognition and better day-to-day function compared to a control group, who took a placebo.
If these results are confirmed by future studies – as always the funding issue – memantine could quickly become a mainstay choice Fibromyalgia treatment.
This key research study was done in Spain. Subjects who met the American College of Rheumatology 1990 case definition for Fibromyalgia were recruited to take either memantine or a placebo.
During the six-month trial subjects taking memantine had substantially less pain, improved cognitive ability, and better day-to-day function than did patients taking a placebo. Statistically significant improvement occurred within the first month and persisted throughout the entire six months long trial.
Memantine’s side effects tend to be mild. There are relatively few adverse interactions with other drugs. So, if these encouraging results are confirmed by further studies, Namenda (memantine) could quickly become a mainstay treatment.
Dr. Barbara Olivan-Blazquez, Dr. Javier Garcia-Campayo and their team from Zaragosa University recruited about 60 long-term fibromyalgia patients. Half received memantine, the others took a placebo.
They measured pain status in two different ways. First, they used a visual analogue scale where patient rate their subjective perception of pain on a scale of zero to 10. Zero means no pain. Ten is the worst pain possible.
After one month on memantine, the average visual analogue score decreased from 6.56 to 4.83. That is, the memantine patients reported less pain. In contrast, subjects taking placebo modestly increased their pain score from 6.48 to 6.64. The difference favoring the memantine group was highly significant (P=0.001). Significant differences favoring the memantine group continued throughout the six-month long study.
A second way to measure pain was to pump up a blood pressure cuff. At baseline, the memantine group subjects complained of pain when the blood pressure cuff average reading was 97.9 millimeters of Mercury (mmHg). One month later, it required an average blood pressure of 112 mmHg. before pain was noted. Thus, pain sensitivity had decreased. Patients on the placebo showed the opposite – a mild increase in their sensitivity to blood pressure cuff induced pain.
The degree of pain improvement was moderate for most memantine patients, although it was dramatic in a few. Only sixteen percent of the memantine-treated subjects achieved a 50% improvement in pain (5 of 31subjects). BUT none (0%) of the subjects on placebo had that much improvement.
Subjects on memantine also did significantly better than those on placebo for the mini-mental status test of cognitive function, on a depression scale and on several measures of functional activity. The bottom line: Subjects taking memantine tended to feel better while also being more active.
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Is it reasonable for a physician to consider using memantine as an “off label” treatment for fibromyalgia? We have only one fairly small study. So we cannot say for sure if memantine “really works.” But, as medicines go, memantine is considered to be fairly safe. Among Alzheimer’s patients, the most common side effects are dizziness, headache, confusion and constipation. Adverse drug interactions are few. But one should avoid mixing memantine with other NMDA receptor antagonist medicines such as amantadine, ketamine and dextromethorphan (the cough suppressant in Delsym).
The Spanish researchers started treating at 5 mg once daily. They titrated over one month to a final dose of 10 mg twice daily. Since people with fibromyalgia tend to be very sensitive to medicine side effects, I would tend to increase the dose even more slowly until we are sure that the patient tolerates the medicine.
The big obstacle I foresee is how to gain funding sufficient to repeat the Spanish study. Memantine is available as a generic. So there may be little incentive for Forest Laboratories (who makes brand name Namenda) or the generic manufacturers to spend the millions of dollars that would be needed to obtain FDA approval for them to promote memantine as a Fibromyalgia treatment.
Happily, the Spanish government provided major financial support for the Zaragosa research.
We do owe profound thanks to Dr Olivan-Blazquez, Dr. Garcia-Campayo and the Zaragoza group for putting memantine on our map.
I hope that we at ProHealth.com can help create a mechanism through which physicians and patients who take memantine “off label” can tell others in the Fibro community how their treatment went.
This is the Key Article:
Olivan-Blazquez, B…. Garcia-Campayo, J, Efficacy of memantine in the treatment of fibromyalgia: A double-blind randomized, controlled trial with 6-month follow-up. Pain 155 (2014): 2517-2515.
You can see the complete accepted but unedited manuscript at: http://www.thblack.com/links/RSD/Pain2014_inpress_memantine4FM-1stCT-32p.pdf
Fayed, N…Garcia-Campayo, J, Changes in Metabolites after Treatment with Memantine in Fibromyalgia. A double-blind randomized Controlled Trial with Magnetic Resonance Spectroscopy with a 6-month follow-up, CNS Neuroscience & Therapeutics, 20(2014): 999-1007
Serra, G, …Kahn, D, Memantine in the Treatment and Prophylaxis of Bipolar II Disorder and Comorbid Fibromyalgia: A case Report, Journal of Psychiatric Practice 20 (2014): 232-6
Richard Podell, M.D., MPH is a graduate of Harvard Medical School and the Harvard School of Public Health. He has been treating patients with ME-CFS and Fibromyalgia for more than 20 years. A clinical professor at New Jersey's Robert Wood Johnson Medical School, Dr. Podell see patients at his Summit, NJ and Somerset, NJ offices. His website is www.DrPodell.org