The Effects of Safinamide Adjunct Therapy on Depression and Apathy in Patients With Parkinson's Disease: Post-hoc Analysis of a Japanese Phase 2/3 Study

Optimized use of safinamide as an add-on therapy in Asian patients with Parkinson's disease: a narrative review and expert opinion

Parkinson's disease (PD) imposes a large burden on Asian countries and threatens to grow rapidly as Asian populations age. PD phenotypes in Asian patients differ from those reported in the West, yet management generally follows a similar approach. Levodopa (l-dopa) is a mainstay of therapy and is typically followed by the addition of a catechol-O-methyltransferase inhibitor or a monoamine oxidase-B (MAO-B) inhibitor to address the wearing-off effect. There is little guidance on switching between MAO-B inhibitors or other adjunct therapies that consider the newer evidence for safinamide as an add-on PD therapy in Asian patients. Therefore, a group of PD experts in Asia evaluated the evidence supporting safinamide for the treatment of PD with a focus on integrating this treatment option into local clinical practice. A narrative review was conducted to identify supportive evidence for the formulation of summary statements on key topics. The efficacy and safety of safinamide added to l-dopa in Asian patients with PD are supported by both clinical trials and observational data, including two randomized trials enrolling exclusively Asian patients (n = 406; n = 307) and an Asian subpopulation analysis from another randomized trial (n = 173). Safinamide reduces wear-off duration and has beneficial effects on motor symptoms of PD, with good tolerability outcomes. Safinamide may also have beneficial effects on non-motor symptoms of PD such as urinary symptoms, apathy and sleep disturbances, and it is a suitable treatment for older patients. Overall, safinamide is an effective and well-tolerated treatment for the wear-off effect of l-dopa in Asian patients and, during long-term treatment, might reduce the risk of dyskinesia in patients without pre-existing dyskinesia. Additional research is needed to better understand the role of safinamide for patients with fluctuating pain, the dose-effect relationship of safinamide in Asian patients and the efficacy of safinamide in Asian patients with early-onset PD.

Long-Term Real-World Experience with Safinamide in Patients with Parkinson's Disease

INTRODUCTION

Randomized clinical trials should be complemented with data from real-world studies. We report our long-term experience with safinamide in a movement disorders unit.

METHODS

This retrospective study included patients with Parkinson's disease (PD) treated with safinamide in our unit from February 2016 to May 2022 under routine clinical practice. Assessments included the Hoehn and Yahr (HY) stage, unified Parkinson's disease rating scale (UPDRS) part III score, levodopa equivalent daily dose (LEDD), LEDD for dopamine agonists, and safinamide treatment discontinuation.

RESULTS

We included 180 patients with a median age of 74 years (IQR 11), and the majority (90.6%) had an HY stage of ≤2. After a median follow-up of 40 months (IQR 34), 14 patients discontinued treatment with safinamide (7.8%, 95% CI 4.7 to 12.6). Among the 166 patients who remained on safinamide, the UPDRS III score was stable (10 (IQR 9) vs. 9 (IQR 13), p = 0.455). The LEDD significantly increased from a median of 300 mg to 500 mg (p < 0.001), whereas the LEDD for dopamine agonists did not significantly increase. A subgroup of 89 patients who did not require dopamine agonists during follow-up showed stable UPDRS III score (10 (IQR 7) vs. 9 (IQR 14); p = 0.923), with a significant LEDD increase (300 mg to 400 mg, p < 0.001).

CONCLUSIONS

Our results support the long-term effectiveness and tolerability of safinamide in patients with PD in clinical practice.

Pharmacotherapy of motor symptoms in early and mid-stage Parkinson's disease: guideline "Parkinson's disease" of the German Society of Neurology

BACKGROUND AND OBJECTIVE

There are multiple pharmacological treatment options for motor symptoms of Parkinson's disease (PD). These comprise multiple drug classes which are approved for the condition, including levodopa, dopamine agonists, COMT inhibitors, MAO-B inhibitors, NMDA-receptor antagonists, anticholinergics, and others. Some of the drugs are approved for monotherapy and combination therapy while others are only approved as adjunctive therapy to levodopa. Furthermore, treatment for special treatment situations, e.g., rescue medication for off-phases, for tremor, treatment during pregnancy and breast feeding is discussed and recommendations are given with further details.

METHODS

The recommendations were based on systematic literature reviews, drafted by expert teams, consented in online polls followed by online consensus meetings of the whole German Parkinson's Guideline Group, and publicly released in November 2023.

RESULTS

In the new S2k (i.e., consensus-based) guidelines, the pharmacotherapy of the motor symptoms of PD is discussed in five chapters. These comprise "Parkinson medication", "Initial monotherapy", "Early combination therapy", "Fluctuations and dyskinesia", and "Parkinsonian tremor". Furthermore, there is a chapter for special treatment situations, including perioperative management, freezing of gait, and pregnancy and breastfeeding.

CONCLUSION

The recommendations for the pharmacotherapy of motor symptoms of PD have been updated. Newly available drugs have been added, while other drugs (e.g., ergoline dopamine agonists, anticholinergics, budipine) have been removed from the recommendations.

Safinamide as adjunctive therapy to levodopa monotherapy for patients with Parkinson's disease with wearing-off: The Japanese observational J-SILVER study

BACKGROUND

Safinamide is an effective adjunctive therapy for wearing-off in Parkinson's disease (PD); however, evidence is lacking in older patients and those in the early stages of wearing-off. This study evaluated the efficacy and safety of safinamide as adjunctive therapy in patients with PD treated with levodopa monotherapy in clinical practice.

METHODS

This multicentre, open-label observational study was conducted at five sites in Japan. Patients diagnosed with PD and wearing-off initiated safinamide as adjunctive therapy with levodopa monotherapy. Efficacy endpoints were mean changes in Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part I, III, and IV scores; daily ON-time without dyskinesia using 24-h patient symptom diaries; and 39-item Parkinson's Disease Questionnaire (PDQ-39) scores at 18 weeks of treatment.

RESULTS

In total, 24 patients initiated safinamide (66.7% were aged ≥75 years); the mean duration of wearing-off was 1.2 years. MDS-UPDRS Part III total score, Part IV total score, and PDQ-39 summary index decreased significantly from baseline (mean change -7.0 [p = 0.012], -2.4 [p = 0.007] and - 5.3 [p = 0.012], respectively). There was a non-statistically significant increase of 1.55 h in mean daily ON-time without dyskinesia. Numerical Rating Scale total score for pain (p = 0.015), and scores for OFF-period pain (p = 0.012) and nocturnal pain (p = 0.021) subdomains were significantly improved in the subgroup with pain. Most reported adverse events were classified as mild.

CONCLUSION

Safinamide improved motor and non-motor symptoms and quality of life-related measures in older patients with PD in the early stages of wearing-off without new safety concerns.

STUDY REGISTRATION

University Hospital Medical Information Network in Japan; study ID: UMIN000044341.

Safinamide, an inhibitor of monoamine oxidase, modulates the magnitude, gating, and hysteresis of sodium ion current

BACKGROUND

Safinamide (SAF), an α-aminoamide derivative and a selective, reversible monoamine oxidase (MAO)-B inhibitor, has both dopaminergic and nondopaminergic (glutamatergic) properties. Several studies have explored the potential of SAF against various neurological disorders; however, to what extent SAF modulates the magnitude, gating, and voltage-dependent hysteresis [Hys(V)] of ionic currents remains unknown.

METHODS

With the aid of patch-clamp technology, we investigated the effects of SAF on voltage-gated sodium ion (NaV) channels in pituitary GH3 cells.

RESULTS

SAF concentration-dependently stimulated the transient (peak) and late (sustained) components of voltage-gated sodium ion current (INa) in pituitary GH3 cells. The conductance-voltage relationship of transient INa [INa(T)] was shifted to more negative potentials with the SAF presence; however, the steady-state inactivation curve of INa(T) was shifted in a rightward direction in its existence. SAF increased the decaying time constant of INa(T) induced by a train of depolarizing stimuli. Notably, subsequent addition of ranolazine or mirogabalin reversed the SAF-induced increase in the decaying time constant. SAF also increased the magnitude of window INa induced by an ascending ramp voltage Vramp. Furthermore, SAF enhanced the Hys(V) behavior of persistent INa induced by an upright isosceles-triangular Vramp. Single-channel cell-attached recordings indicated SAF effectively increased the open-state probability of NaV channels. Molecular docking revealed SAF interacts with both MAO and NaV channels.

CONCLUSION

SAF may interact directly with NaV channels in pituitary neuroendocrine cells, modulating membrane excitability.

Impact of Safinamide on Patient-Reported Outcomes in Parkinson's Disease

Introduction

Parkinson's disease (PD) is a chronic and progressive neurodegenerative condition due to the degeneration of nigral dopaminergic cells. Both motor and non-motor symptoms (NMS) of PD produce a marked impairment in PD patients' quality of life (QoL), but contrary to motor features, NMS do not improve with dopamine replacement. Novel therapeutic interventions for PD have successfully controlled most motor manifestations of PD, but the management of NMS is still challenging. Since NMS have a negative impact on the QoL of PD patients, researchers are currently looking for drugs that can modulate the activity of neurotransmitter systems other than dopamine in the hope that can alleviate NMS in PD. Among the recently approved drugs for patients experiencing fluctuations in motor symptoms, safinamide stands out as an effective add-on therapy to levodopa. Safinamide is a monoamine oxidase type-B inhibitor (MAOB-I), with proven efficacy in reducing motor fluctuations. Its distinctive mechanism of action impacts dopaminergic pathways via MAOB inhibition and glutamatergic pathways by blocking sodium and calcium channels. Findings from Phase III clinical trials, meta-analysis, post-hoc analysis, and real-life experiences indicate that safinamide benefits motor symptoms such as tremor, bradykinesia, rigidity, and gait. Additionally, it shows promise for improving NMS like fatigue, pain, mood, and sleep disturbances in patients with PD.

Areas Covered

In this article, the authors explore the impact of safinamide on patient-reported outcomes in PD. A thorough search was conducted on PubMed focusing on studies published between 2018 and 2023 in English. The inclusion criteria encompassed clinical trials, randomized controlled trials, systematic reviews, meta-analyses, and reviews. The search strategy revolved around the implementation of MeSH terms related to safinamide and its impact on the quality of life in PD.

Conclusion

Our data strongly support the improving effect on QoL, reducing the disabling NMS reported in patients with PD.

A Systematic Review of Pharmacological Interventions for Apathy in Aging Neurocognitive Disorders

OBJECTIVE

Apathy, a frequent neuropsychiatric symptom in aging neurocognitive disorders, has been associated with cognitive decline and functional disability. Therefore, timely provision of pharmacological interventions for apathy is greatly needed.

DESIGN

A systematical literature review of existing studies was conducted up to 30 May 2023 in several databases (PubMed, PsychInfo, Cochrane, Google Scholar, etc.) that included randomized controlled trials (RCTs) and meta-analyses assessing pharmacological treatments for apathy in aging neurocognitive disorders. The quality of the studies was appraised.

RESULTS

In patients with Alzheimer's Disease (AD), donepezil, galantamine, rivastigmine, methylphenidate, and gingko biloba were proven efficacious for apathy, while rivastigmine, cognitive enhancer IRL752 and piribedil were found to be beneficial in patients with Parkinson's Disease (PD) and agomelatine in patients with Frontotemporal Dementia (FD). The extensive proportion of RCTs in which apathy was used as a secondary outcome measure, along with the considerable methodological heterogeneity, did not allow the evaluation of group effects.

CONCLUSIONS

Pharmacological interventions for apathy in aging neurocognitive disorders are complex and under-investigated. The continuation of systematic research efforts and the provision of individualized treatment for patients suffering from these disorders is vital.