The FDA approved istradefylline(Nourianz) as an add-on treatment to levodopa/carbidopa in adult patients with Parkinson's disease experiencing "off" episodes, the agency announced late Tuesday. Istradefylline is an orally administered, selective adenosine A2A receptor antagonist and has been marketed in Japan since 2013 as adjunctive treatment to levodopa-containing products for Parkinson's patients. The FDA decision this week caps drugmaker Kyowa Kirin's second try at winning approval; in 2008, the agency rejected the drug due to efficacy concerns. This time, the company presented four 12-week placebo-controlled clinical studies, involving 1,143 Parkinson's disease patients on levodopa/carbidopa, to demonstrate istradefyelline's effectiveness. In all four studies, patients treated with istradefylline showed reductions from baseline in daily "off" time relative to patients using placebo. The most common adverse reactions experienced in the trials were dyskinesia, dizziness, constipation, nausea, hallucination, and insomnia. Patients should be monitored for the development or exacerbation of existing dyskinesia, the FDA said; if hallucinations or psychotic or impulsive/compulsive behaviors occur, the dose should be reduced or the drug should be stopped. Istradefylline is not recommended for pregnant women. Istradefylline is distinct from other Parkinson's drugs which act on dopamine metabolism or dopamine receptors. A meta-analysis published in 2017 found that 40 mg/day of the drug could improve "off" time and motor symptoms in patients with Parkinson's disease. Source
