Add-on safinamide and amantadine in Filipino Parkinson's disease patients with motor fluctuations: a retrospective exploratory cohort study.

To describe and compare short-term motor fluctuation-related outcomes among ambulatory Filipino patients with Parkinson's disease receiving dopamine replacement therapy alone or with add-on safinamide or amantadine. This single-center retrospective exploratory cohort study included adult Filipino patients with idiopathic Parkinson's disease and motor fluctuations lasting > 1.5 h, excluding morning akinesia. Eligible patients had at least three follow-up clinic visits, were receiving dopamine replacement therapy, and had a stable Levodopa-equivalent dose for at least 4 weeks before screening. Patients were grouped according to physician-directed treatment received in routine clinical practice: dopamine replacement therapy alone, dopamine replacement therapy plus amantadine, or dopamine replacement therapy plus safinamide. Outcomes assessed after 8 weeks included change in ON time, Unified Parkinson's Disease Rating Scale parts III and IV, and modified Hoehn and Yahr stage. Thirty patients were included, with 10 patients in each treatment group. Significant baseline differences were observed in age (p = 0.01), age at Parkinson's disease onset (p = 0.02), baseline Unified Parkinson's Disease Rating Scale part IV score (p = 0.04), and Levodopa-equivalent dose per day (p < 0.001). In unadjusted analyses, change in ON time and Unified Parkinson's Disease Rating Scale part IV score differed significantly across groups, while Unified Parkinson's Disease Rating Scale part III score and modified Hoehn and Yahr stage did not. In exploratory adjusted models, the group effect for ON time change was not statistically significant after adjustment for age (p = 0.052) and Levodopa-equivalent dose per day (p = 0.093), but remained significant after separate adjustment for age at Parkinson's disease onset (p = 0.014) and disease duration (p = 0.008). Adverse events were reported in 16 patients (53%) and were summarized descriptively. One patient in the safinamide group discontinued add-on therapy during follow-up but completed the 8-week outcome assessment. In this small retrospective exploratory cohort, short-term changes in ON time and motor complication scores were observed among Filipino patients with Parkinson's disease receiving dopamine replacement therapy alone or with add-on safinamide or amantadine. However, baseline imbalances, small sample size, non-randomized treatment allocation, and limitations in outcome assessment preclude conclusions regarding comparative treatment efficacy. These findings should be interpreted as preliminary and hypothesis-generating.