Adenosine A(2A) receptor antagonist istradefylline reduces daily OFF time in Parkinson’s disease

BackgroundWe evaluated the efficacy and safety of istradefylline, a selective adenosine A(2A) receptor antagonist administered as adjunctive treatment to levodopa for 12 weeks in a double-blind manner in Parkinson’s disease patients with motor complications in Japan. MethodsA total of 373 subjects were randomized to receive placebo (n = 126), istradefylline 20 mg/day (n = 123), or istradefylline 40 mg/day (n = 124). The primary efficacy variable was the change in daily OFF time. Other secondary variables were also evaluated. ResultsThe change in daily OFF time was significantly reduced in the istradefylline 20 mg/day (−0.99 hours, P = .003) and istradefylline 40 mg/day (−0.96 hours, P = .003) groups compared with the placebo group (−0.23 hours). The most common adverse event was dyskinesia (placebo, 4.0%; istradefylline 20 mg/day, 13.0%; istradefylline 40 mg/day, 12.1%). ConclusionsIstradefylline reduced daily OFF time and was well tolerated in Japanese PD patients with motor complications on levodopa treatment.