Safinamide as an Adjunct to Levodopa in Asian and Caucasian Patients With Parkinson’s Disease and Motor Fluctuations: A Post Hoc Analysis of the SETTLE Study

OBJECTIVE: Safinamide is a selective, reversible monoamine oxidase B inhibitor with demonstrated efficacy and tolerability in placebo-controlled studies and is clinically useful for patients with motor fluctuations. This study evaluated the efficacy and safety of safinamide as a levodopa adjunct therapy in Asian patients with Parkinson’s disease. METHODS: Data from 173 Asian and 371 Caucasian patients from the international Phase III SETTLE study were included in this post hoc analysis. The safinamide dose was increased from 50 mg/day to 100 mg/day if no tolerability issues occurred at week 2. The primary outcome was the change from baseline to week 24 in daily ON-time without troublesome dyskinesia (i.e., ON-time). Key secondary outcomes included changes in Unified Parkinson’s Disease Rating Scale (UPDRS) scores. RESULTS: Safinamide significantly increased daily ON-time relative to placebo in both groups (least-squares mean: 0.83 hours, p = 0.011 [Asians]; 1.05 hours, p < 0.0001 [Caucasians]). Motor function relative to placebo (UPDRS Part III) improved significantly in Asians (-2.65 points, p = 0.012) but not Caucasians (-1.44 points, p = 0.0576). Safinamide did not worsen Dyskinesia Rating Scale scores in either subgroup, regardless of the presence or absence of dyskinesia at baseline. Dyskinesia was largely mild for Asians and moderate for Caucasians. None of the Asian patients experienced adverse events leading to treatment discontinuation. CONCLUSION: Safinamide as a levodopa adjunct is well tolerated and effective in reducing motor fluctuations in both Asian and Caucasian patients. Further studies to investigate the real-world effectiveness and safety of safinamide in Asia are warranted.