Introduction: 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.
Objectives: 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.
Methods: 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.
Results: 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).
Conclusions: 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.