Fluoxetine is an FDA-approved drug for treating depression that is now being tested in people with secondary progressive MS.
How does fluoxetine work?
Fluoxetine is a selective serotonin reuptake inhibitor, or SSRI. It works by increasing the amount of serotonin in the brain. Serotonin is a chemical messenger thought to influence mood. Previous research has suggested that fluoxetine also has a neuroprotective effect, which means it could be used to treat MS. What people with progressive MS need the most are neuroprotective or disease-modifying treatments that show or stop the progression of the disease.
Fluoxetine research in Progressive MS
The objective of the Fluoxetine for Progressive MS study in Belgium and the Netherlands was to see if fluoxetine could slow the progression of MS. The trial (ECTRIM2016) covered both people with primary progressive MS and secondary progressive MS. Participants were divided into two groups. The 69 people in the first group received a 40 mg-per-day dose of fluoxetine (Prozac) for 108 weeks. The 68 people in the second group received a placebo.
Researchers found no significant difference in disease progression between the two groups. The study showed fluoxetine tended to reduce the progression of disabilities associated with MS, but failed to significantly improve the conditions of people with progressive MS.
Another study of fluoxetine is the MS-SMART clinical trial, which is under way. The Phase 2 randomized and blinded study is aimed at comparing the mechanism of action and effectiveness of fluoxetine and two other neuroprotective drugs, riluzole and amiloride, in people with secondary progressive MS. Randomized means participants can receive any of the three drugs or an inactive placebo. Blinded means that neither participants nor doctors will know which drug a patient is receiving.
MS patients are already using the three drugs. The new study is looking at how effective they are against second progressive MS, not other forms of the disease.
All three drugs target one or more of the pathways that lead to the neurodegeneration seen in secondary progressive MS. All have shown promise in early MS studies. And all have good safety records.
The MS-SMART study has recruited 440 people with secondary progressive MS and a high disease disability score. Disability is measured by EDSS, the Expanded Disability Status Scale.
Trial participants who receive amiloride will get 5 mg a day in the first four weeks and 5 mg twice a day for the rest of the 96 weeks. Those receiving riluzole will get 50 mg a day the first four weeks and 50 mg twice a day after that. Those receiving fluoxetine (Prozac) will receive 20 mg a day the first four weeks and 20 mg twice a day after that. A control group will receive one capsule a day of a placebo for the 96 weeks.
All participants will have MRI brain scans before their treatment starts, at six months and when the study ends in two years.
Researchers will compare the scans of those who took each drug and the placebo to see if any of the therapies slows the rate of  brain deterioration that occurs in secondary progressive MS. Another measures of the study’s effectiveness will be doctors’ assessments of the neuroprotection that each drug afforded.
The research team hopes to complete the study by July 2018. If fluoxetine (Prozac) appears to be effective against secondary progressive MS, it will be tested again in Phase 3 studies. The ultimate goal is to have the Federal Drug Administration license it for use against progressive secondary MS.
Other details
Researchers have yet to determine the side effects that fluoxetine (Prozac) will have on people with MS. The expectation is that they will be similar to the side effects it generates as a depression or fatigue treatment. These include insomnia, strange dreams, headache, dizziness, vision changes, tremors or shaking, emotional disorders, pain, tiredness, gastric disorders, dry mouth, sweating, hot flashes, eating disorders, flu-like symptoms, decreased sex drive, impotence, and difficulty having an orgasm.
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