Amantadine ER (Gocovri®) Significantly Increases ON Time Without Any Dyskinesia: Pooled Analyses From Pivotal Trials in Parkinson's Disease

5-HT4R agonism reduces L-DOPA-induced dyskinesia via striatopallidal neurons in unilaterally 6-OHDA lesioned mice

Parkinson's disease is caused by a selective vulnerability and cell loss of dopaminergic neurons of the Substantia Nigra pars compacta and, consequently, striatal dopamine depletion. In Parkinson's disease therapy, dopamine loss is counteracted by the administration of L-DOPA, which is initially effective in ameliorating motor symptoms, but over time leads to a burdening side effect of uncontrollable jerky movements, termed L-DOPA-induced dyskinesia. To date, no efficient treatment for dyskinesia exists. The dopaminergic and serotonergic systems are intrinsically linked, and in recent years, a role has been established for pre-synaptic 5-HT1a/b receptors in L-DOPA-induced dyskinesia. We hypothesized that post-synaptic serotonin receptors may have a role and investigated the effect of modulation of 5-HT4 receptor on motor symptoms and L-DOPA-induced dyskinesia in the unilateral 6-OHDA mouse model of Parkinson's disease. Administration of RS 67333, a 5-HT4 receptor partial agonist, reduces L-DOPA-induced dyskinesia without altering L-DOPA's pro-kinetic effect. In the dorsolateral striatum, we find 5-HT4 receptor to be predominantly expressed in D2R-containing medium spiny neurons, and its expression is altered by dopamine depletion and L-DOPA treatment. We further show that 5-HT4 receptor agonism not only reduces L-DOPA-induced dyskinesia, but also enhances the activation of the cAMP-PKA pathway in striatopallidal medium spiny neurons. Taken together, our findings suggest that agonism of the post-synaptic serotonin receptor 5-HT4 may be a novel therapeutic approach to reduce L-DOPA-induced dyskinesia.

Amantadine use in the French prospective NS-Park cohort

OBJECTIVE

To assess amantadine use and associated factors in the patients with Parkinson's disease (PD).

BACKGROUND

Immediate-release amantadine is approved for the treatment of PD and is largely used in clinical practice to treat "levodopa-induced dyskinesia (LIDs). Its use varies according to countries and PD stages. The prospective NS-Park cohort collects features of PD patients followed by 26 French PD Expert Centres.

METHODS

Variables used for the analyses included demographics, motor and non-motor PD symptoms and motor complications [motor fluctuations (MFs), LIDs)], antiparkinsonian pharmacological classes and levodopa equivalent daily dose (LEDD). We evaluated: (i) prevalence of amantadine use and compared clinical features of amantadine users vs. non-users (cross-sectional analysis); (ii) factors associated with amantadine initiation (longitudinal analysis); (iii) amantadine effect on LIDs, MFs, apathy, impulse control disorders and freezing of gait (Fog) (longitudinal analysis).

RESULTS

Amantadine use prevalence was 12.6% (1,585/12,542, median dose = 200 mg). Amantadine users were significantly younger, with longer and more severe PD symptoms, greater LEDD and more frequent use of device-aided/surgical treatment. Factors independently associated with amantadine initiation were younger age, longer PD duration, more frequent LIDs, MFs and FoG, higher LEDD and better cognitive function. 9 of the 658 patients on amantadine had stopped it at the following visit, after 12-18 months (1.3%). New users of amantadine presented a higher improvement in LIDs and MF compared to amantadine never users.

CONCLUSIONS

About 12% of PD patients within the French NS-Park cohort used amantadine, mostly those with younger age and more severe PD. Amantadine initiation was associated with a subsequent reduction in LIDs and MFs.

Novel and experimental therapeutics for the management of motor and non-motor Parkinsonian symptoms

BACKGROUND  : Both motor and non-motor symptoms of Parkinson's disease (PD) have a substantial detrimental influence on the patient's quality of life. The most effective treatment remains oral levodopa. All currently known treatments just address the symptoms; they do not completely reverse the condition.

METHODOLOGY

In order to find literature on the creation of novel treatment agents and their efficacy for PD patients, we searched PubMed, Google Scholar, and other online libraries.

RESULTS

According to the most recent study on Parkinson's disease (PD), a great deal of work has been done in both the clinical and laboratory domains, and some current scientists have even been successful in developing novel therapies for PD patients.

CONCLUSION

The quality of life for PD patients has increased as a result of recent research, and numerous innovative medications are being developed for PD therapy. In the near future, we will see positive outcomes regarding PD treatment.

Doxycycline to treat levodopa-induced dyskinesias in Parkinson's disease: a preliminary study

BACKGROUND

 Levodopa-induced dyskinesia (LID) is a common motor complication of levodopa therapy in patients with Parkinson's disease (PD). Doxycycline is a widely used and inexpensive tetracycline with anti-inflammatory properties.

OBJECTIVE

 To evaluate the efficacy and safety of doxycycline in patients with PD and LID.

METHODS

 This was an open-label, uncontrolled, single-arm, single-center, phase 2 proof-of-concept study in patients with PD with functional impact of dyskinesia, which used levodopa three times daily, in a movement disorders clinic in Brazil. Participants were treated with doxycycline 200 mg/day for 12 weeks, with evaluations at baseline, week 4, and week 12 of treatment. The primary outcome measure was the change from baseline in the Unified Dyskinesia Rating Scale (UDysRS) total score at week 12, evaluated by two blinded raters. Key secondary outcomes measures were OFF time and ON time with troublesome dyskinesia in the PD home diary.

RESULTS

 Eight patients with PD were treated and evaluated. Doxycycline 200 mg/day reduced the UDysRS total score at week 12, compared with baseline (Friedman χ² = 9.6; p = 0.008). Further, doxycycline reduced the ON time with troublesome dyskinesia (Friedman χ² = 10.8; p = 0.004) without worsening parkinsonism. There were no severe adverse events, and dyspepsia was the commonest event.

CONCLUSION

 In this preliminary, open-label and uncontrolled trial, doxycycline was effective in reducing LID and safe after a 12-week treatment. Further well-designed placebo-controlled clinical trials with a longer duration and a larger number of participants are needed.

CLINICAL TRIAL REGISTRATION

 https://ensaiosclinicos.gov.br, identifier: RBR-1047fwbf.

Levodopa-Induced Dyskinesia in Parkinson's Disease: Pathogenesis and Emerging Treatment Strategies

The most commonly used treatment for Parkinson's disease (PD) is levodopa, prescribed in conjunction with carbidopa. Virtually all patients with PD undergo dopamine replacement therapy using levodopa during the course of the disease's progression. However, despite the fact that levodopa is the "gold standard" in PD treatments and has the ability to significantly alleviate PD symptoms, it comes with side effects in advanced PD. Levodopa replacement therapy remains the current clinical treatment of choice for Parkinson's patients, but approximately 80% of the treated PD patients develop levodopa-induced dyskinesia (LID) in the advanced stages of the disease. A better understanding of the pathological mechanisms of LID and possible means of improvement would significantly improve the outcome of PD patients, reduce the complexity of medication use, and lower adverse effects, thus, improving the quality of life of patients and prolonging their life cycle. This review assesses the recent advancements in understanding the underlying mechanisms of LID and the therapeutic management options available after the emergence of LID in patients. We summarized the pathogenesis and the new treatments for LID-related PD and concluded that targeting pathways other than the dopaminergic pathway to treat LID has become a new possibility, and, currently, amantadine, drugs targeting 5-hydroxytryptamine receptors, and surgery for PD can target the Parkinson's symptoms caused by LID.

Newly Approved and Investigational Drugs for Motor Symptom Control in Parkinson's Disease

Motor symptoms are a core feature of Parkinson's disease (PD) and cause a significant burden on patients' quality of life. Oral levodopa is still the most effective treatment, however, the motor benefits are countered by inherent pharmacologic limitations of the drug. Additionally, with disease progression, chronic levodopa leads to the appearance of motor complications including motor fluctuations and dyskinesia. Furthermore, several motor abnormalities of posture, balance, and gait may become less responsive to levodopa. With these unmet needs and our evolving understanding of the neuroanatomic and pathophysiologic underpinnings of PD, several advances have been made in defining new therapies for motor symptoms. These include newer levodopa formulations and drug delivery systems, refinements in adjunctive medications, and non-dopaminergic treatment strategies. Although some are in early stages of development, these novel treatments potentially widen the available options for the management of motor symptoms allowing clinicians to provide an individually tailored care for PD patients. Here, we review the existing and emerging interventions for PD with focus on newly approved and investigational drugs for motor symptoms, motor fluctuations, dyskinesia, and balance and gait dysfunction.

A Randomized Clinical Trial to Evaluate the Effects of Safinamide on Apathetic Non-demented Patients With Parkinson's Disease

Background

Apathy is highly prevalent and disabling in Parkinson's disease (PD). Pharmacological options for its management lack sufficient evidence.

Objective

We studied the effects of safinamide on apathy in PD.

Methods

Prospective, 24-week, two-site, randomized, double-blind, placebo-controlled, parallel-group exploratory study in non-demented PD on stable dopaminergic therapy randomized 1:1 to adjunct safinamide (50 mg/day for 2 weeks and 100 mg/day for 22 weeks) or placebo. The primary endpoint was the mean change from baseline to week 24 on the Apathy Scale (AS) total score. Secondary endpoints included changes in cognition, activities of daily living, motor scores, the impression of change, and safety and tolerability measures.

Results

In total, 30 participants (active treatment = 15; placebo = 15; 80% showing clinically significant apathetic symptoms according to the AS) were enrolled, and included in the intention-to-treat analysis. Change in AS (ANOVA) showed a trend to significance [p = 0.059] mediated by a more marked decrease in AS score with safinamide (−7.5 ± 6.9) than with placebo (−2.8 ± 5.7). Post-hoc analysis (paired t-test) showed a significant positive change in the AS score between 12-week and 24-week [p = 0.001] only in the active group. No significant or trend changes were found for any of the secondary outcome variables. Adverse events were few and only mild in both treatment groups.

Conclusions

Safinamide was safe and well-tolerated, but failed to provide evidence of improved apathy. The positive trend observed in the post-hoc analyses deserves to be studied in depth in larger studies.

Trial Registration

EudraCT 2017-003254-17.

Molecular Mechanisms and Therapeutic Strategies for Levodopa-Induced Dyskinesia in Parkinson's Disease: A Perspective Through Preclinical and Clinical Evidence

Parkinson's disease (PD) is the second leading neurodegenerative disease that is characterized by severe locomotor abnormalities. Levodopa (L-DOPA) treatment has been considered a mainstay for the management of PD; however, its prolonged treatment is often associated with abnormal involuntary movements and results in L-DOPA-induced dyskinesia (LID). Although LID is encountered after chronic administration of L-DOPA, the appearance of dyskinesia after weeks or months of the L-DOPA treatment has complicated our understanding of its pathogenesis. Pathophysiology of LID is mainly associated with alteration of direct and indirect pathways of the cortico-basal ganglia-thalamic loop, which regulates normal fine motor movements. Hypersensitivity of dopamine receptors has been involved in the development of LID; moreover, these symptoms are worsened by concurrent non-dopaminergic innervations including glutamatergic, serotonergic, and peptidergic neurotransmission. The present study is focused on discussing the recent updates in molecular mechanisms and therapeutic approaches for the effective management of LID in PD patients.

Amantadine delayed release/extended release capsules significantly reduce OFF time in Parkinson's disease

Maintaining consistent levodopa benefits while simultaneously controlling dyskinesia can be difficult. Recently, an amantadine delayed release/extended release (DR/ER) formulation (Gocovri^®) indicated for dyskinesia received additional FDA approval as an adjunct to levodopa for the treatment of OFF episodes. We evaluated OFF time reductions with amantadine-DR/ER in a pooled analysis of two phase III amantadine-DR/ER trials (NCT02136914, NCT02274766) followed by a 2-year open-label extension trial (NCT02202551). OFF outcomes were analyzed for the mITT population, as well as stratified by baseline OFF time of ≥2.5 h/day or <2.5 h/day. At Week 12, mean placebo-subtracted treatment difference in OFF time was −1.00 [−1.57, −0.44] h in the mITT population (n = 196), −1.2 [−2.08, −0.32] h in the ≥2.5 h subgroup (n = 102) and −0.77 [−1.49, −0.06] in the <2.5 h subgroup (n = 94). Amantadine-DR/ER-treated participants showed reduced MDS-UPDRS Part IV motor fluctuation subscores by week 2 that were maintained below baseline to Week 100.

A Randomized, Double-Blind, Controlled Phase II Study of Foliglurax in Parkinson's Disease

BACKGROUND

Agents targeting the metabotropic glutamate receptor 4 have emerged as a potentially attractive new class of drugs for the treatment of Parkinson's disease (PD).

OBJECTIVE

The objective of this study was to evaluate the efficacy and safety of foliglurax in reducing off time and dyskinesia in patients with PD.

METHODS

This was a 28-day, multicenter, randomized, placebo-controlled, double-blind clinical trial of foliglurax 10 and 30 mg as adjunct to levodopa in 157 randomly assigned patients with PD and motor complications.

RESULTS

Although dose-dependent decreases in daily awake off time were apparent following treatment with foliglurax, the change from baseline to day 28 in off time (primary endpoint) and dyskinesia (secondary endpoint) did not improve significantly compared with placebo for either foliglurax dose. Treatment with foliglurax was generally safe, and there were no relevant safety signals.

CONCLUSIONS

There was no evidence in this study that foliglurax has efficacy in improving levodopa-induced motor complications in PD. © 2022 International Parkinson and Movement Disorder Society.

GOCOVRI® (amantadine) extended-release capsules in Parkinson's disease

Amantadine is an old, antiviral compound, which moderately improves motor behavior in Parkinson's disease. Its current resurgence results from an innovative, delayed uptake and extended release amantadine hydrochloride capsule, given at bedtime once daily. It is the only approved compound for reduction of involuntary movements, so called dyskinesia, in fluctuating orally levodopa treated patients. It additionally ameliorates 'off'-intervals characterized by impaired motor behavior. These beneficial effects result from higher and more continuous brain delivery of amantadine. Future clinical research is warranted on preventive effects of this amantadine capsule combined with enzyme blockers of central monoamine oxidase B and peripheral catechol-O-methyltransferase on motor complications in orally levodopa treated patients, as all these pharmacological principles support the concept of continuous dopamine substitution.

Amantadine Revisited: A Contender for Initial Treatment in Parkinson's Disease?

The best practice for the initiation of symptomatic motor treatment for Parkinson's disease is an ongoing topic of debate. Fueled by interpretation of the results of the LEAP and MED Parkinson's disease studies, many practitioners opt for early initiation of levodopa formulations, avoiding dopamine agonists to circumvent potential deleterious side effects, namely impulse control disorder. Compared with levodopa, monoamine oxidase inhibitors may lack necessary potency. Ignored in this academic debate is another therapeutic option for patients with Parkinson's disease requiring treatment initiation: amantadine. Amantadine was first reported effective in the treatment of Parkinson's disease in 1969 and several studies were published in the 1970s supporting its efficacy. Currently, amantadine is mainly utilized as an add-on therapy to mitigate levodopa-related dyskinesia and, more recently, new long-acting amantadine formulations have been developed, with new indications to treat motor fluctuations. Amantadine has not been reported to cause dyskinesia and is rarely implicated in impulse control disorder.

Current Knowledge on the Background, Pathophysiology and Treatment of Levodopa-Induced Dyskinesia-Literature Review

Levodopa remains the primary drug for controlling motor symptoms in Parkinson’s disease through the whole course, but over time, complications develop in the form of dyskinesias, which gradually become more frequent and severe. These abnormal, involuntary, hyperkinetic movements are mainly characteristic of the ON phase and are triggered by excess exogenous levodopa. They may also occur during the OFF phase, or in both phases. Over the past 10 years, the issue of levodopa-induced dyskinesia has been the subject of research into both the substrate of this pathology and potential remedial strategies. The purpose of the present study was to review the results of recent research on the background and treatment of dyskinesia. To this end, databases were reviewed using a search strategy that included both relevant keywords related to the topic and appropriate filters to limit results to English language literature published since 2010. Based on the selected papers, the current state of knowledge on the morphological, functional, genetic and clinical features of levodopa-induced dyskinesia, as well as pharmacological, genetic treatment and other therapies such as deep brain stimulation, are described.