Dyskinesia can be confusing. These involuntary movements can look like smooth tics or an uncoordinated dance, and may be part of how people think of Parkinson’s disease. But they are not part of the disease itself. Dyskinesia is a side effect of levodopa — the gold standard medication for Parkinson’s motor symptoms tremor and rigidity — and can significantly impact quality of life.
“If we could control dyskinesia, it would probably be the biggest change in terms of how we treat patients,” said Susan Bressman, MD, chair of the Department of Neurology at Beth Israel Medical Center in New York City, in an MJFF video on dyskinesia.
Physicians have long thought that dyskinesia arose with long-term use of levodopa, so patients may delay starting medication and live with disabling symptoms in an attempt to “save” the window of efficacy before dyskinesia begins. While more recent research is showing that levodopa-induced dyskinesia may be influenced more by stage of disease than length of medication use, a treatment for this side effect would be a game-changer for many patients.
Last week pharmaceutical company Adamas announced it is a step closer to such a therapy with positive findings from a Phase III study of extended-release amantadine. People who took the drug (called ADS-5102) showed a 23 percent reduction in dyskinesia compared to people who received a placebo.
To measure the effect of ADS-5102, researchers used the Unified Dyskinesia Rating Scale, a critical tool validated with funding from The Michael J. Fox Foundation. In 2012 MJFF supported a study of the scale to determine its utility in testing dyskinesia treatments. The validation of the rating scale shows it is a solid measure of a drug’s impact, and may help the U.S. Food and Drug Administration assess the utility of ADS-5102 when deciding on approval.
Interestingly, researchers used amantadine (the same compound as ADS-5102) to validate the rating scale. Amantadine is approved as a treatment for influenza, but physicians have used it to treat dyskinesia. The drug blocks receptors of neurotransmitter glutamate, which scientists believe is involved in causing this side effect. This extended-release formulation could help control dyskinesia throughout the day.
Join us January 21 for our next Third Thursdays Webinar to learn more about dyskinesia, how physicians manage this medication side effect, and new therapies in development, including ADS-5102.