Istradefylline: adenosine A2A receptor antagonist to reduce "OFF" time in Parkinson's disease.

Parkinson's disease (PD) is an extremely common degenerative disease with a progressive course. Unfortunately, the longer patients are treated with levodopa, the more likely they are to suffer from increasingly long periods of immobility or "OFF" time. For over 30 years Kyowa Kirin Co., Ltd. (formerly Kyowa Hakko Kirin Co., Ltd.) has been researching the possibility of finding drugs that affect adenosine receptors and that can be used successfully as additional drugs in the treatment of PD. Istradefylline is an adenosine A2A receptor antagonist that significantly reduces the "OFF" time and improves the motor function of patients with PD, as measured by the Unified Parkinson's Disease Rating Scale (UPDRS) Part III, while increasing the time without troublesome dyskinesia. It was approved for use in PD in Japan in 2013 and in the United States in 2019.