Prozac® (fluoxetine, Eli Lilly and Company), a drug approved to treat depression, showed some signs of reducing disease activity in a small, short-term study involving 40 people with MS and no depression when compared with inactive placebo. However, the researchers did not see a significant difference in the cumulative number of new, active MRI brain lesions, the primary outcome measure of the study. Dr. J. P. Mostert and colleagues (University of Groningen, The Netherlands) report their findings in the Journal of Neurology, Neurosurgery, and Psychiatry (Published Online First: 1 May 2008). This was an exploratory study, meaning that it was not designed with enough statistical power to truly determine effectiveness, but rather collect information for further studies.
Multiple sclerosis occurs when the immune system attacks and damages the brain and spinal cord. Research indicates that a molecule called “cAMP” may be helpful in reducing this attack. Serotonin, a neurotransmitter, has been shown to increase cAMP levels. Fluoxetine, a drug that increases serotonin to treat depression, has been found to increase cAMP levels in mice. Fluoxetine is approved for treating mental depression, panic disorder, and other mood disorders, and is used occasionally to treat MS-related fatigue.
Dr. Mostert’s group recruited 40 non-depressed people with relapsing-remitting* or secondary-progressive** MS. They administered fluoxetine (one 20-mg tablet daily) or placebo for 24 weeks. The primary endpoint of the study was the cumulative number of new, active lesions (areas of damage to nerve-fiber insulating myelin) that appeared on MRI brain scans taken at intervals throughout the study. Secondary outcomes that the investigators measured included the number of relapses and disease activity (as measured by clinical scales). This was an exploratory study, meaning that it was not designed with enough statistical power to truly determine effectiveness, but rather collect information for further studies.
Two patients (one taking fluoxetine, the other on placebo) withdrew due to nausea. The mean cumulative number of new, active lesions tended to be lower in the group taking fluoxetine, but this reduction was not statistically significant. Among secondary outcomes measures, there were significantly fewer MRI scans showing new active lesions in those taking fluoxetine. The number of relapses and disease activity were comparable between the two groups. People using fluoxetine experienced more nausea and drowsiness but most adverse events diminished within a few weeks.
As the authors point out, “conclusions from our results must be made with caution because of the small sample size and exploratory design.” The results of this exploratory study yield limited information on fluoxetine’s ability to impact disease activity in MS, but do indicate a place for further, more statistically powerful studies that would establish fluoxetine’s safety and effectiveness for treating MS.
Read more about fluoxetine as a treatment for mental
depression, panic disorder, or fatigue in MS.
*RR MS Relapsing-remitting MS is a course of MS in which clearly defined flare-ups are followed by partial or complete recovery periods.
**SP MS Secondary-progressive MS, an initial period of relapsing-remitting MS, followed by a steadily worsening disease course with or without occasional flare-ups or minor recoveries.
Prozac is a registered trademark of Eli Lilly and Co.