An updated meta-analysis of amantadine for treating dyskinesia in Parkinson's disease

In recent years, a few of randomized controlled trials (RCTs) about amantadine for treating dyskinesia in Parkinson's disease (PD) were completed. Here, we conducted a systematic literature review about the clinical research to provide the updated evidence for treating dyskinesia. Electronic search of Medline, PubMed, Cochrane Library, and other databases up to May 2016 for relevant studies was performed. We selected the Unified Parkinson's Disease Rating Scale IV (UPDRS IV) and Dyskinesia Rating Scales (DRS) as efficacy outcomes of amantadine on dyskinesia. Pooled data from included studies was then used to carry out meta-analysis. A total of eleven eligible RCTs that involved 356 PD patients with existing dyskinesia were included in the present study. The results of meta-analysis showed that amantadine significantly improved UPDRS IV (P < 0.0001) and DRS (P < 0.00001). Meanwhile, there was a mild reduction in Unified Parkinson's Disease Rating Scale III after amantadine treatment in advanced PD patients with dyskinesia (P = 0.01) compared with placebo. High dosage of amantadine obviously improved existing dyskinesia in PD, yet at the expense of the increased adverse events. It was necessary to detect the optimal therapeutic efficacy to balance the incidence of adverse events when we used amantadine to treat existing dyskinesia in PD patients.