FDA approves drug as add-on treatment for Parkinson's disease patients

The U.S. Food and Drug Administration today approved Xadago (safinamide) tablets as an add-on treatment for patients with Parkinson's disease who are currently taking levodopa/carbidopa and experiencing "off" episodes. An "off" episode is a time when a patient's medications are not working well, causing an increase in Parkinson's symptoms, such as tremor and difficulty walking.

"Parkinson's is a relentless disease without a cure," said Eric Bastings, M.D., deputy director of the Division of Neurology Products in the FDA's Center for Drug Evaluation and Research. "We are committed to helping make additional treatments for Parkinson's disease available to patients."

An estimated 50,000 Americans are diagnosed with Parkinson's disease each year, according to the National Institutes of Health, and about one million Americans have the condition. The neurological disorder typically occurs in people over age 60, though it can occur earlier, when cells in the brain that produce a chemical called 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. Early symptoms of the disease are subtle and occur gradually. In some people, Parkinson's disease progresses more quickly than in others.

The efficacy of Xadago in treating Parkinson's disease was shown in a clinical trial of 645 participants who were also taking levodopa and were experiencing "off" time. Those receiving Xadago experienced more beneficial "on" time, a time when Parkinson's symptoms are reduced, without troublesome uncontrolled involuntary movement (dyskinesia), compared to those receiving a placebo. The increase in "on" time was accompanied by a reduction in "off" time and better scores on a measure of motor function assessed during "on" time than before treatment.

In another clinical trial of 549 participants, the participants adding Xadago to their levodopa treatment had more "on" time without troublesome uncontrolled involuntary movement compared to those taking a placebo, and also had better scores on a measure of motor function assessed during "on" time than before treatment.

Certain patients should not take Xadago. These include patients who have severe liver problems, or who take a medicine used to treat a cough or cold called dextromethorphan. It also should not be taken by patients who take another medicine called a monoamine oxidase inhibitor (MAOI) because it may cause a sudden severe increase in blood pressure, or by those who take an opioid drug, St. John's wort, certain antidepressants (such as serotonin-norepinephrine reuptake inhibitors, tricyclics, tetracyclics, and triazolopyridines), or cyclobenzaprine, because it may cause a life-threatening reaction called serotonin syndrome.

The most common adverse reactions observed in patients taking Xadago were uncontrolled involuntary movement, falls, nausea, and trouble sleeping or falling asleep (insomnia).

Serious, but less common, risks include the following: exacerbated high blood pressure (hypertension); serotonin syndrome when used with MAOIs, antidepressants, or opioid drugs; falling asleep during activities of daily living; hallucinations and psychotic behavior; problems with impulse control/compulsive behaviors; withdrawal-emergent hyperpyrexia (fever) and confusion; and retinal pathology.​