Fibromyalgia: Memantine Reduced Pain in Small, Blinded Trial

Jennifer Garcia

October 08, 2014

Memantine, a drug primarily used to treat patients with Parkinson's disease and Alzheimer's disease, reduced pain and improved quality of life in patients with fibromyalgia, according to a study published online September 15 in Pain.

"This is the first randomised, controlled study of memantine for the treatment of fibromyalgia," write Bárbara Oliván-Blázquez, from the Department of Psychology and Sociology at the University of Zaragoza, Spain, and colleagues. "Consistent with our hypothesis, memantine was significantly effective in the treatment of pain in patients with fibromyalgia relative to placebo, as it was shown to increase pain threshold and decrease pain perception in this disorder."

The randomized, double-blind trial compared a 6-month course of memantine (20 mg daily) with placebo in 63 adult patients with fibromyalgia. Patients receiving other treatments for fibromyalgia were excluded or went through a 1-week washout period before enrollment in the study. Baseline characteristics between the intervention and placebo groups were similar.

The researchers evaluated patients at baseline and 1, 3, and 6 months after initiating therapy. They assessed pain using a pain visual analog scale, and pain tolerance was measured with a sphygmomanometer. They also used standardized questionnaires, including the Fibromyalgia Impact Questionnaire, to evaluate secondary variables such as state of anxiety and depression, cognitive state, and quality of life.

Compared with placebo, patients in the memantine group had a significant decrease in their pain visual analog scale (Cohen's d = 1.43) and pain tolerance (d = 1.05) after 6 months of treatment (P = .001 for both). Secondary outcomes, with the exception of anxiety, also improved among patients in the memantine group.

With respect to adverse events, dizziness was reported in 25.8% of patients in the memantine group versus 12.5% in the placebo group; headache was reported with similar frequency between the two groups (12.9% in the memantine group vs 15.6% in the placebo group).

"These side effects don't seem any worse than the average side effect profile seen with other centrally acting medications" Daniel J. Clauw, MD, from the Chronic Pain and Fatigue Research Center at the University of Michigan, Ann Arbor, told Medscape Medical News.

Dr Clauw, who was not associated with the study, also noted that although other studies that replicate these findings will be needed, "this is a really important study because it theoretically provides another drug treatment for individuals with fibromyalgia."

The authors acknowledged limitations to the study, such as the small sample size, the short follow-up period, and the fact that it was not a multicenter study.

Despite the limitations, one of the study authors, Javier Garcia-Campayo, MD, from the Miguel Servet University Hospital, Zaragoza, Spain, told Medscape Medical News that the drug could be considered an option for these patients. "I think that memantine can be used as an adjuvant pharmacological treatment associated with antidepressants (such as duloxetine) and pain killers (such as pregabalin)."

"Memantine is a very safe and tolerated treatment," noted Dr Garcia-Campayo. "In our study, and in others on dementia and other disorders, withdrawals with memantine are rather low and side effects temporary and mild."

"[A]lthough additional studies with larger samples and longer follow-ups are needed to confirm these results, this study provides preliminary evidence of the utility of memantine for the treatment of many clinical domains in [fibromyalgia]," conclude the authors.

Funding for this study was provided by the Department of Science, Technology and University of the Government of Aragon and by the Carlos III Institute of Health. The authors have disclosed no relevant financial relationships. Dr Clauw has done consulting for and had research funded by Forest Laboratories.

Pain. Published online September 15, 2014. Abstract

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