The FDA has greenlighted safinamide (Xadago, Newron Pharmaceuticals), a selective monoamine oxidase B inhibitor, as an add-on treatment for patients with Parkinson’s disease (PD) who experience “off” episodes while receiving levodopa/carbidopa. An “off” episode is a period when a patient’s medications are not working well, causing an increase in PD symptoms, such as tremor and difficulty walking.
The efficacy of safinamide in treating patients with PD was demonstrated in a trial involving 645 subjects who were also taking levodopa and were experiencing “off” time. The subjects treated with safinamide experienced more beneficial “on” time––a period when PD symptoms are reduced––without dyskinesia compared with those receiving placebo. The increase in “on” time was accompanied by a reduction in “off” time and by better scores on a measure of motor function.
In another study involving 549 participants, those adding safinamide to their levodopa treatment had more “on” time without dyskinesia compared with those given placebo. The safinamide group also had better scores on a measure of motor function.
The most common adverse events associated with safinamide include uncontrolled involuntary movement, falls, nausea, and insomnia.
Serious but less-common risks of safinamide include exacerbated hypertension; serotonin syndrome when used with monoamine oxidase inhibitors (MAOIs), antidepressants, or opioid drugs; falling asleep during the activities of daily living; hallucinations and psychotic behavior; problems with impulse control/compulsive behaviors; withdrawal-emergent hyperpyrexia and confusion; and retinal pathology.
Certain patients should not take safinamide, such as those with severe liver disease or those taking dextromethorphan. Moreover, safinamide should not be used in patients taking MAOIs because the drug may cause a sudden severe increase in blood pressure, or in those taking an opioid drug, St. John’s wort, certain antidepressants (such as serotonin–norepinephrine reuptake inhibitors, tricyclics, tetracyclics, and triazolopyridines), or cyclobenzaprine because such combination treatment may cause life-threatening serotonin syndrome.
An estimated 50,000 Americans are diagnosed with PD each year, according to the National Institutes of Health, and approximately one million Americans have the disorder. PD usually occurs in people older than 60 years of age, although it can occur earlier, when cells in the brain that produce dopamine become impaired or die. Dopamine helps transmit signals between the areas of the brain that produce smooth, purposeful movement, such as eating, writing, and shaving.
Source: FDA; March 21, 2017.