Utilization Patterns of Amantadine in Parkinson's Disease Patients Enrolled in the French COPARK Study

Immediate-release (IR) amantadine has been marketed for Parkinson's disease (PD) therapy for 50 years, while two novel extended-release formulations have only recently reached the market in the US.

The aim of this study was to describe amantadine IR utilization patterns in the French COPARK cohort, at baseline and after 2 years of follow-up.

Overall, 683 PD patients from the COPARK survey were evaluated. All patients were assessed in a standardized manner (demographics, treatments, Unified Parkinson's Disease Rating Scale [UPDRS], Hospital Anxiety and Depression Scale, Pittsburg Questionnaire and health-related quality-of-life scales (Short Form-36 [SF-36], 39-item Parkinson's Disease Questionnaire [PDQ-39]). Longitudinal data were only available for 401/683 patients (59%) with a median (P25-75) follow-up period of 23 months (18-31). Patients were assessed in the same way as in the baseline visit.

At baseline, amantadine was prescribed to 61/683 (9%) patients (median dose 200 mg/day, range 100-300 mg/day). Amantadine was initiated after a median of 7 years from PD diagnosis, and its prescription was correlated with the presence of dyskinesia (logistic regression odds ratio [OR] 3.72, 95% confidence interval [CI] 1.95-7.08) and hallucinations (UPDRS I.2) [OR 1.57, 95% CI 1.08-2.29]. After 2 years, the amantadine prescription increased from 33 (8%) patients at baseline to 54 (14%) patients in the subset of 401 patients analysed twice (p = 0.001). Among the 33 patients receiving amantadine at baseline, 9 (27%) stopped amantadine, 5 (15%) increased the dose, 6 (18%) reduced the dose and 13 (40%) stayed at the same doses. Treatment was initiated in 30/54 new patients (55%). Patients who started amantadine or increased its dose (n = 35) had more levodopa-induced dyskinesias at baseline (OR 7.02, 95% CI 3.09-15.90) and higher Mini-Mental State Examination score at follow-up (OR 1.37, 95% CI 1.06-1.79). Undergoing deep brain stimulation was related to stopping or downtitrating amantadine (OR 22.02, 95% CI 4.24-114.44; n = 15).

In this cohort, amantadine was used in 10% of patients. Its use increased during follow-up, despite the fact that one-third of patients who received amantadine at baseline stopped taking it. Amantadine prescription was mainly correlated with the presence of dyskinesia.