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October 16, 2007 (Prague, Czech Republic) -- Fluoxetine (Prozac) may help reduce the number of new brain lesions in patients with multiple sclerosis (MS), according to a study presented here at the ECTRIMS 2007: 23rd Congress of the European Committee for Treatment and Research in Multiple Sclerosis.

The study, which was conducted by Jop P. Mostert, MD, and colleagues at the University of Groningen, the Netherlands, shows a trend toward a reduction in new enhancing lesions with fluoxetine treatment in patients with relapsing-remitting or relapsing secondary progressive MS.

Why Fluoxetine?

Fluoxetine, a selective serotonin reuptake inhibitor, was approved by the US Food and Drug Administration in 1987 and is frequently prescribed for the treatment of various psychiatric disorders, including major depression. However, fluoxetine also has a number of immunomodulatory effects, and previous studies have indicated that it might be beneficial for patients with MS, Dr. Mostert said in his presentation.

One of these earlier studies, which was first presented at the 1997 Annual Meeting of the American Association of Neurology, showed that fluoxetine reduced disease activity in experimental autoimmune encephalomyelitis, the animal model of MS, Dr. Mostert noted. "Furthermore, psychiatrists already reported in 1991 reduced MS in patients using fluoxetine," he added.

Previous research has also found that astrocytes in patients with MS lack beta-2 adrenergic receptors, and this leads to decreased cyclic adenosine monophosphate (cAMP) production, which in turn contributes to the initiation of the inflammatory cascade that eventually results in demyelination, Dr. Mostert explained. Because fluoxetine is able to increase the amount of cAMP in the astrocyte, the researchers hypothesized that the drug could help compensate for the loss of beta-2 adrenergic receptors and thus, reduce the amount of inflammation in MS.

Fewer New Lesions

To test their hypothesis, Dr. Mostert's team enrolled 40 patients (age 18 - 65 years) with relapsing-remitting or relapsing secondary progressive MS in a randomized, double-blind, placebo-controlled trial, with a duration of 24 weeks. Half of the patients were given fluoxetine (20 mg/day), whereas the remaining subjects received placebo.

The primary end point was the cumulative number of new gadolinium-enhancing lesions on T1-weighted magnetic resonance imaging (MRI) of the brain performed at weeks 4, 8, 16, and 24. Secondary outcome measures included changes in the Expanded Disability Status Scale (EDSS) and in the Multiple Sclerosis Self-Efficacy Scale (MSSE) from baseline to week 24.

The investigators found that the study drug was generally well tolerated, with only 1 patient dropping out because of adverse effects (nausea) in the treatment group. One patient also dropped out from the placebo group, leaving 19 completers in each group.

Regarding the primary end point, the results show that there was a trend toward a reduction in the number of new enhancing lesions in patients treated with fluoxetine. The mean (SD) cumulative number of new enhancing lesions during the 24 weeks of treatment was 1.84 (2.9) in the fluoxetine-treated patients and 5.16 (8.6) in the control subjects (P = .15).

At week 4, the cumulative number of new enhancing lesions was "quite comparable" in the two 2 groups, pointed out Dr. Mostert. He emphasized, however, that in the latter part of the trial, there was a steady increase in new lesions in the placebo group, while the number of lesions in the fluoxetine-treated patients remained relatively stable. Restricting the analysis to the last 16 weeks showed a "nearly significant" reduction in the cumulative number of new enhancing lesions and a higher number of patients without new enhancing lesions (63% vs 26%; P = .02).

Commenting on the study, session cochair Roland Liblau, MD, PhD, from Toulouse University Hospital in France, noted that the researchers used "a very interesting approach," because fluoxetine has a very good safety profile.

"It has been used in hundreds of thousands of patients, so we know it's safe," he told Medscape Neurology and Neurosurgery. "The possibility that it has even a slight effect in multiple sclerosis would be very interesting," he added. "The data showed a trend toward efficacy in MS, and I would strongly encourage further trials involving more patients."

This study was an investigator-initiated trial, with no pharmaceutical industry funding.

Pearls for Practice

• In a 24-week, randomized, double-blind, placebo-controlled trial of 40 patients with relapsing-remitting or relapsing secondary progressive MS, there was a nonsignificant trend toward a reduction in the number of new enhancing MRI lesions in patients treated with fluoxetine, 20 mg/day. At week 4, the cumulative number of new enhancing lesions was similar in both groups. However, in the last 16 weeks, there was a nearly significant reduction in the cumulative number of new enhancing lesions and a higher number of patients without new enhancing lesions.
• Fluoxetine was generally well tolerated, and only 1 patient dropped out because of adverse effects (nausea) in the treatment group. One patient also dropped out from the placebo group. Fluoxetine has a very good safety profile.

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