FDA Approves Istradefylline for Treatment of “Off” Periods in Parkinson’s Disease

The Food and Drug Administration (FDA) has approved istradefylline (Nourianz; Kyowa Kirin, Tokyo, Japan) as an adjunctive therapy to levodopa/carbidopa for adults with Parkinson’s disease (PD) to treat symptoms of off periods. Unlike other treatments for PD, istradefylline is not dopaminergic, but rather is an adenosine A_2A receptor inhibitor. Istradefylline significantly reduced the time spent in off periods for people with PD compared to treatment with placebo in 4 clinical trials that included over 1,100 participants. 

Off periods occur in 40% of people with PD. During the off period, when the previous dose of levodopa/carbidopa is wearing off, but the next dose has yet to come “on,” fluctuations of PD symptoms occur. These can make daily activities of living during the off period challenging to impossible. 

“Istradefylline is an Adenosine A_2A receptor antagonist, and is a novel non-dopaminergic pharmacologic approach to treating OFF episodes for people living with PD,” said Dr. Stuart Isaacson, MD, Parkinson’s Disease and Movement Disorders Center of Boca Raton, Florida. “Based on data from four clinical studies, istradefylline taken as an adjunct to levodopa significantly improved OFF time and demonstrated a well-tolerated safety profile. Istradefylline represents an important new treatment option for patients with Parkinson's disease who experience 'OFF' episodes.”

“We are proud that Nourianz is now ready to help adult patients with Parkinson’s disease in the US,” said Tomohiro Sudo, Head of Global Product Management Office of Kyowa Kirin. “We believe that Nourianz could be an important contributor to improve treatment outcomes. We will keep working to bring the product to patients globally.”

In clinical trials, side effects included dyskinesia or worsening of dyskinesia in 1% of participants. People with hallucinations, impulse control problems, or compulsive behaviors, all of which can occur in late-stage PD, should have use a lower dose or discontinue istradefylline.