Levodopa is the most efficacious treatment for Parkinson's disease (PD). 
Long-term treatment with levodopa is limited due to dyskinesia. Dyskinesia in PD 
can be socially and functionally disabling. Extended-release amantadine 
(amantadine ER) is the first approved medication for the treatment of 
dyskinesia. When it is given at bedtime, it reaches plasma concentration 
approximately twice the level achieved by amantadine immediate release. 
Amantadine ER reduces the severity and duration of dyskinesia during the day, 
reduces OFF time and increases ON time without troublesome dyskinesia. The most 
common side effects are hallucination, dizziness, orthostatic hypotension and 
pedal edema. This review discusses the safety and efficacy of amantadine ER in 
dyskinesia in PD patients.