ADS-5102 (Amantadine) Extended-Release Capsules for Levodopa-Induced Dyskinesia in Parkinson Disease (EASE LID Study): A Randomized Clinical Trial

A bioactive sprite: Recent advances in the application of vinyl sulfones in drug design and organic synthesis

Vinyl sulfones, with their exceptional chemical properties, are known as the "chameleons" of organic synthesis and are widely used in the preparation of various sulfur-containing structures. However, their most alluring feature lies in their biological activity. The vinyl sulfone skeleton is ubiquitous in natural products and drug molecules and boasts a unique molecular structure and drug activity when compared to conventional drug molecules. As a result, vinyl sulfones have been extensively studied, playing a critical role in organic synthesis and pharmaceutical chemistry. In this review, we present a comprehensive analysis of the recent applications of vinyl sulfone structures in drug design, biology, and chemical synthesis. Furthermore, we explore the prospects of vinyl sulfones in diverse fields, offering insight into their potential future applications.

Efficacy and safety of Tianqi Pingchan Granule, a compound Chinese herbal medicine, for levodopa-induced dyskinesia in Parkinson's disease: A randomized double-blind placebo-controlled trial

BACKGROUND

Patients with Parkinson's disease (PD) undergoing long-term levodopa therapy are prone to develop levodopa-induced dyskinesia (LID). Amantadine is the main drug recommended for the treatment of LID by current guidelines, but it is far from meeting clinical needs. Tianqi Pingchan Granule (TPG), a compound Chinese herbal medicine, has been developed to relieve symptom of LID.

OBJECTIVE

This randomized controlled trial evaluated the efficacy and safety of the combination of TPG and amantadine for LID.

DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS

This is a randomized double-blind placebo-controlled trial, conducted from January 2020 to August 2021 at 6 sites in Jiangsu, Zhejiang and Shanghai, China. One hundred PD patients with ≥ 0.5 h of LID were randomly assigned to either the TPG plus amantadine group (TPG group) or the placebo plus amantadine group (placebo group), and treated for a period of 12 weeks. To ensure unbiased results, all study participants, investigators and sponsors were unaware of group allocations. Additionally, the data analysts remained blinded until the analysis was finalized.

MAIN OUTCOME MEASURES

The primary outcome was assessed using the Unified Dyskinesia Rating Scale (UDysRS) (Range 0-104). The key secondary end point was improvement of motor and non-motor symptoms. Safety analyses included all enrolled patients.

RESULTS

One hundred patients were enrolled and randomized into the two treatment groups. The changes in UDysRS at week 12 were -11.02 for the TPG group and -4.19 for the placebo group (treatment difference -6.83 [-10.53 to -3.12]; P = 0.0004). Adverse events were reported for 2 of 50 patients (4.0%) in each of the groups.

CONCLUSION

This study indicated that a 12-week treatment of amantadine plus TPG effectively reduced UDysRS scores and was well tolerated, demonstrating the efficacy and safety of TPG for the treatment of LID in PD.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04173832.

PLEASE CITE THIS ARTICLE AS

Zhang Y, Zhu XB, Zhao Y, Cui GY, Li WT, Yuan CX, Huang JP, Wan Y, Wu N, Song L, Zhao JH, Liang Y, Xu CY, Liu MJ, Gao C, Chen XX, Liu ZG. Efficacy and safety of Tianqi Pingchan Granule, a compound Chinese herbal medicine, for levodopa-induced dyskinesia in Parkinson's disease: A randomized double-blind placebo-controlled trial. J Integr Med. 2024; Epub ahead of print.

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.

Extended-release amantadine for OFF-related dystonia in Parkinson's disease

INTRODUCTION

Dystonia is a painful OFF-related complication in Parkinson's disease (PD) with limited treatment options.

METHODS

Post-hoc analysis using pooled data from two extended-release amantadine pivotal trials and follow-on open-label extension. Dystonia was assessed using the Unified Dyskinesia Rating Scale (UDysRS) Part 2 and the Movement Disorder Society-Unified PD Rating Scale (MDS-UPDRS) item 4.6.

RESULTS

Of 196 participants, 119 (60.7%) reported OFF-related dystonia at baseline per UDysRS. Twelve-week treatment with extended-release amantadine improved OFF dystonia (treatment differences vs placebo: UDysRS Part 2, -1.0 [-1.9,-0.1]; p = 0.03 and MDS-UPDRS Item 4.6, -0.3 [-0.6,-0.05]; p = 0.02). There was no correlation between changes in OFF time and changes in OFF dystonia. Double-blind improvements in OFF dystonia were sustained throughout the 2-year follow-up.

CONCLUSIONS

Extended-release amantadine yielded a sustained reduction in OFF-related dystonia in PD patients that was independent from a reduction in OFF time. A randomized controlled trial is warranted to confirm these findings.

Using artificial intelligence to identify drugs for repurposing to treat l-DOPA-induced dyskinesia

Repurposing regulatory agency-approved molecules, with proven safety in humans, is an attractive option for developing new treatments for disease. We identified and assessed the efficacy of 3 drugs predicted by an in silico screen as having the potential to treat l-DOPA-induced dyskinesia (LID) in Parkinson's disease. We analysed ∼1.3 million Medline abstracts using natural language processing and ranked 3539 existing drugs based on predicted ability to reduce LID. 3 drugs from the top 5% of the 3539 candidates; lorcaserin, acamprosate and ganaxolone, were prioritized for preclinical testing based on i) having a novel mechanism of action, ii) having not been previously validated for the treatment of LID, iii) being blood-brain-barrier penetrant and orally bioavailable and iv) being clinical trial ready. We assessed the efficacy of acamprosate, ganaxolone and lorcaserin in a rodent model of l-DOPA-induced hyperactivity, with lorcaserin affording a 58% reduction in rotational asymmetry (P < 0.05) compared to vehicle. Acamprosate and ganaxolone failed to demonstrate efficacy. Lorcaserin, a 5HT2C agonist, was then further tested in MPTP lesioned dyskinetic macaques where it afforded an 82% reduction in LID (P < 0.05), unfortunately accompanied by a significant increase in parkinsonian disability. In conclusion, although our data do not support the repurposing of lorcaserin, acamprosate or ganaxolone per se for LID, we demonstrate value of an in silico approach to identify candidate molecules which, in combination with an in vivo screen, can facilitate clinical development decisions. The present study adds to a growing literature in support of this paradigm shifting approach in the repurposing pipeline.

Comparative efficacy and safety of adjunctive drugs to levodopa for fluctuating Parkinson's disease - network meta-analysis

It remains unclear which adjunctive drug for Parkinson's disease (PD) in combination with levodopa is more effective, tolerable, and safe. We aimed to compare the efficacy, tolerability, and safety among anti-PD drugs from several classes in patients with fluctuating PD who received levodopa through network meta-analysis (NMA). Twelve anti-PD drugs belonging to 4 different drug classes (dopamine agonists, monoamine oxidase type B inhibitors, catechol-O-methyl transferase inhibitors, and an adenosine A2A receptor antagonist) were selected. We systematically searched PubMed, Embase, and the Cochrane Library for eligible randomized controlled trials (RCTs) comparing placebo with anti-PD drug or among anti-PD drugs in patients with PD who experienced motor fluctuations or wearing-off and received levodopa. We included 54 RCTs in the analysis. The NMA was performed under a frequentist framework using a random-effects model. The efficacy outcome was change in daily off-time, and the tolerability outcome was discontinuation due to all causes. Safety outcomes included discontinuation due to adverse events (AEs) and the incidence of AEs, dyskinesia, hallucination, and orthostatic hypotension. According to the surface under the cumulative ranking curve (SUCRA) in the NMA, ropinirole transdermal patch (SUCRA, 0.861) ranked the highest in efficacy, followed by pramipexole (0.762), ropinirole extended release (ER) (0.750), and safinamide (0.691). In terms of tolerability, ropinirole (0.954) ranked the highest, followed by pramipexole (0.857), safinamide (0.717), and ropinirole ER (0.708). Each anti-PD drug had different SUCRA ranking profiles for the safety outcomes. These findings suggest that ropinirole, pramipexole, and safinamide are well-balanced anti-PD drugs that satisfy both efficacy and tolerability outcomes.

Safety review of current pharmacotherapies for levodopa-treated patients with Parkinson's disease

INTRODUCTION

Levodopa remains the gold standard for treatment of Parkinson's disease (PD). Patients develop complications with disease progression, necessitating adjunctive therapy to control fluctuations in motor and non-motor symptoms and dyskinesia. Knowledge of medication safety and tolerability is critical to ascertain the benefit-risk ratio and select an adjunctive therapy that provides the highest chance for medication adherence. Posing a challenge are the sheer abundance of options, stemming from the development of several new drugs in recent years, as well as differences in commercial drug availability worldwide.

AREAS COVERED

This review evaluates the efficacy, safety, and tolerability of current US FDA-approved pharmacotherapies for levodopa-treated PD patients, including dopamine agonists, monoamine oxidase type-B inhibitors, catechol-O-methyltransferase inhibitors, the N-methyl-D-aspartate receptor antagonist amantadine, and the adenosine receptor antagonist istradefylline. Data were taken from pivotal phase III randomized controlled and post-surveillance studies, when available, that directly led to FDA-approval.

EXPERT OPINION

No strong evidence exists to support use of a specific adjunctive treatment for improving Off time. Only one medication has demonstrated improvement in dyskinesia in levodopa-treated PD patients; however, every patient cannot tolerate it and therefore adjunctive therapy should be tailored to an individual's symptoms and risk for specific adverse effects.

Targeting Sigma Receptors for the Treatment of Neurodegenerative and Neurodevelopmental Disorders

The sigma-1 receptor is a 223 amino acid-long protein with a recently identified structure. The sigma-2 receptor is a genetically unrelated protein with a similarly shaped binding pocket and acts to influence cellular activities similar to the sigma-1 receptor. Both proteins are highly expressed in neuronal tissues. As such, they have become targets for treating neurological diseases, including Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), multiple sclerosis (MS), Rett syndrome (RS), developmental and epileptic encephalopathies (DEE), and motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). In recent years, there have been many pre-clinical and clinical studies of sigma receptor (1 and 2) ligands for treating neurological disease. Drugs such as blarcamesine, dextromethorphan and pridopidine, which have sigma-1 receptor activity as part of their pharmacological profile, are effective in treating multiple aspects of several neurological diseases. Furthermore, several sigma-2 receptor ligands are under investigation, including CT1812, rivastigmine and SAS0132. This review aims to provide a current and up-to-date analysis of the current clinical and pre-clinical data of drugs with sigma receptor activities for treating neurological disease.

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.

Altered Amantadine Effects after Repetitive Treatment for l-dopa-induced Involuntary Movements in a Rat Model of Parkinson's Disease

BACKGROUND

l-3,4-dihydroxyphenylalanine (l-dopa) is the most effective drug for Parkinson's disease (PD); however, most PD patients develop motor fluctuations including wearing-off and l-dopa-induced dyskinesia (LID). Amantadine is beneficial for improving the motor symptoms, reducing "off" time, and ameliorating LID, although its long-term efficacy remains unknown.

OBJECTIVES

To investigate the effects of amantadine on PD and LID using a rat model with repetitive drug treatment.

METHOD

We utilized 6-hydroxydopamine injections to develop a hemiparkinsonian rat model. The rats were assigned to four groups: five rats received l-dopa and benserazide for 31 days, six rats received l-dopa and benserazide plus amantadine for 31 days, five rats received l-dopa and benserazide for 15 days followed by l-dopa and benserazide plus amantadine for 16 days, and five rats received l-dopa and benserazide plus amantadine for 15 days followed by l-dopa and benserazide treatment for 16 days. We evaluated the l-dopa-induced abnormal involuntary movements on treatment days 1, 7, 14, 16, 22, and 29. Subsequently, immunohistochemistry for drebrin was performed.

RESULTS

l-dopa-induced abnormal movements were reduced on the first day of amantadine treatment, and these effects disappeared with repetitive treatment. In contrast, the extension of l-dopa "on" time was observed after repetitive amantadine treatment. All groups showed enlarged drebrin immunoreactive dots in the dopamine-denervated striatum, indicating that amantadine did not prevent priming effects of repetitive l-dopa treatment.

CONCLUSION

Anti-LID effect of amantadine diminished after repetitive treatment, and the effect of amantadine on wearing-off emerged after repetitive treatment in a hemiparkinsonian rat model. Fluctuations in amantadine effects should be considered when using it in clinical settings.

The Clinical Development of Levodopa Inhalation Powder

ABSTRACT

Oral levodopa is the most effective treatment for Parkinson disease, but OFF periods emerge over time. Gastrointestinal dysfunction and food effects impact levodopa absorption, contributing to unpredictable control of OFF periods. Inhaled levodopa powder (Inbrija) is approved for on-demand treatment of OFF periods in patients receiving oral levodopa-dopa decarboxylase inhibitors. The 84-mg dose is administered via a breath-actuated inhaler. It provides pulmonary delivery of levodopa to the systemic circulation and is taken when a patient has an OFF period in between doses of regular oral levodopa medication. The pivotal SPAN-PD trial in patients experiencing OFF periods on oral dopaminergic therapy showed that levodopa inhalation powder 84 mg produced significant improvement in Unified Parkinson Disease Rating Scale Part III score, as measured 30 minutes postdose at week 12, and improvement was seen as early as 10 minutes. More patients in the levodopa inhalation powder group turned ON within 60 minutes of treatment and remained ON at 60 minutes than in the placebo group. Levodopa inhalation powder can also be used to treat early-morning OFF periods and, when used for up to 12 months, produced no clinically significant differences in pulmonary function compared with an untreated cohort. Levodopa inhalation powder 84 mg increased plasma levodopa concentration rapidly and with less variability than oral levodopa/carbidopa (25/100 mg). Most common adverse event associated with levodopa inhalation powder is cough, found in ~15% of patients in the SPAN-PD trial; otherwise, reported adverse events were consistent with those known to be associated with oral levodopa.

Recent Advances in Drug Therapy for Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease manifesting with motor and non-motor symptoms. Current treatment mainly relies on medication as a symptomatic therapy modulating neurotransmitters. Dopamine replacement therapy has been established, and levodopa is the gold standard for treatment of PD. However, the emergence of motor complications, such as a wearing-off phenomenon, is a clinical problem. Both primary symptoms and motor complications have been targets for the development of treatments for PD. Recent progression in the management of motor complications is supported by newly developed agents and advances in device and formulation technology to deliver drugs continuously. Elucidation of the pathophysiology of PD and the development of disease-modifying therapy that affects the underlying fundamental pathophysiology of the disease are also progressing. In this review, we introduce current knowledge on developments concerning medications for patients with PD.

An Update on Nondopaminergic Treatments for Motor and Non-motor Symptoms of Parkinson's Disease

Nondopaminergic neurotransmitters such as adenosine, norepinephrine, serotonin, glutamate, and acetylcholine are all involved in Parkinson's disease (PD) and promote its symptoms. Therefore, nondopaminergic receptors are key targets for developing novel preparations for the management of motor and non-motor symptoms in PD, without the potential adverse events of dopamine replacement therapy. We reviewed English-written articles and ongoing clinical trials of nondopaminergic treatments for PD patients till 2014 to summarize the recent findings on nondopaminergic preparations for the treatment of PD patients. The most promising research area of nondopaminergic targets is to reduce motor complications caused by traditional dopamine replacement therapy, including motor fluctuations and levodopa-induced dyskinesia. Istradefylline, Safinamide, and Zonisamide were licensed for the management of motor fluctuations in PD patients, while novel serotonergic and glutamatergic agents to improve motor fluctuations are still under research. Sustained- release agents of Amantadine were approved for treating levodopa induced dyskinesia (LID), and serotonin 5HT1B receptor agonist also showed clinical benefits to LID. Nondopaminergic targets were also being explored for the treatment of non-motor symptoms of PD. Pimavanserin was approved globally for the management of hallucinations and delusions related to PD psychosis. Istradefylline revealed beneficial effect on daytime sleepiness, apathy, depression, and lower urinary tract symptoms in PD subjects. Droxidopa may benefit orthostatic hypotension in PD patients. Safinamide and Zonisamide also showed clinical efficacy on certain non-motor symptoms of PD patients. Nondopaminergic drugs are not expected to replace dopaminergic strategies, but further development of these drugs may lead to new approaches with positive clinical implications.

Pharmacological Treatment of Tremor in Parkinson's Disease Revisited

The pathophysiology of Parkinson's disease (PD) tremor remains incompletely understood and there is a lack of clinical trials specifically addressing its pharmacological treatment. Levodopa is the most efficacious drug for most patients and should be used as primary approach to control troublesome tremor. While the efficacy of oral dopamine agonists on PD tremor has been demonstrated in controlled trials, there is no evidence of greater antitremor efficacy compared to levodopa. The magnitude of the antitremor effect of anticholinergics is generally lower than that of levodopa. Due to their adverse effects, anticholinergics have a limited role in selected young and cognitively intact patients. Propranolol may improve resting and action tremor and may be considered as an adjunct in patients with insufficient tremor response to levodopa and this also applies to clozapine, despite its unfavorable adverse effect profile. Treating motor fluctuations with MAO-B and COMT inhibitors, dopamine agonists, amantadine, or on-demand treatments such as subcutaneous or sublingual apomorphine and inhaled levodopa as well as with continuous infusions of levodopa or apomorphine will improve off period tremor episodes. For patients with drug-refractory PD tremor despite levodopa optimization deep brain stimulation and focused ultrasound are first-line considerations. Surgery can also be highly effective for the treatment medication-refractory tremor in selected patients without motor fluctuations. The present review highlights the clinical essentials of parkinsonian tremor, critically examines available trial data on the effects of medication and surgical approaches and provides guidance for the choice of treatments to control PD tremor in clinical practice.

Clinically important change on the Unified Dyskinesia Rating Scale among patients with Parkinson's disease experiencing dyskinesia

Background

The Unified Dyskinesia Rating Scale (UDysRS) evaluates dyskinesia in patients with Parkinson's disease (PD). A minimal clinically important change (MCIC)—the smallest change in a treatment outcome that a patient considers important—remains undefined for the UDysRS.

Objective

To utilize pivotal amantadine delayed-release/extended-release (DR/ER) trial data to derive MCICs for the UDysRS total score in patients with PD experiencing dyskinesia.

Methods

Pivotal trials included PD patients with ≥1 h daily ON time with troublesome dyskinesia and baseline scores ≥2 on the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part IV, item 4.2. Patients randomized to amantadine DR/ER or placebo completed two consecutive 24-h diaries before each clinic visit and were evaluated during ON time with dyskinesia using the UDysRS, MDS-UPDRS, and Clinician Global Impression of Change (CGI-C). The UDysRS changes from baseline to week 12 were anchored to corresponding changes in MDS-UPDRS item 4.2 scores. A minimal clinically important improvement in the CGI-C and diary-reported ON time with troublesome dyskinesia (≥0.5 h) were supportive anchors. Receiver operating characteristic curves determined the UDysRS change values optimizing sensitivity and specificity to at least minimal improvement on each anchor.

Results

The analyses included 196 patients. Week 12 UDysRS total score reduction of ≥8 points corresponded to at least minimal MDS-UPDRS item 4.2 improvement. UDysRS reduction of ≥9 points corresponded to decreased ON time with troublesome dyskinesia of ≥0.5 h per patient diaries, and UDysRS reduction of ≥10 points corresponded to at least minimal improvement on the CGI-C.

Conclusion

Anchored to the MDS-UPDRS Part IV, item 4.2, an 8-point reduction in the UDysRS total score can be considered an MCIC for PD patients with dyskinesia.

Preclinical reserpine models recapitulating motor and non-motor features of Parkinson’s disease: Roles of epigenetic upregulation of alpha-synuclein and autophagy impairment

Reserpine is an effective drug for the clinical treatment of hypertension. It also induces Parkinson’s disease (PD)-like symptoms in humans and animals possible through the inhibition of monoamine vesicular transporters, thus decreasing the levels of monoamine neurotransmitters in the brain. However, the precise mechanisms remain unclear. Herein, we aimed to develop a preclinical reserpine model recapitulating the non-motor and motor symptoms of PD and investigate the underlying potential cellular mechanisms. Incubation of reserpine induced apoptosis, led to the accumulation of intracellular reactive oxygen species (ROS), lowered DNA methylation of alpha-synuclein gene, resulted in alpha-synuclein protein deposition, and elevated the ratio of LC3-II/LC3-Ⅰ and p62 in cultured SH-SY5Y cells. Feeding reserpine dose-dependently shortened the lifespan and caused impairment of motor functions in male and female Drosophila. Moreover, long-term oral administration of reserpine led to multiple motor and non-motor symptoms, including constipation, pain hypersensitivity, olfactory impairment, and depression-like behaviors in mice. The mechanistic studies showed that chronic reserpine exposure caused hypomethylation of the alpha-synuclein gene and up-regulated its expression and elevated the ratio of LC3-II/LC3-Ⅰ and expression of p62 in the substantia nigra of mice. Thus, we established preclinical animal models using reserpine to recapitulate the motor and non-motor symptoms of PD. Chronic reserpine exposure epigenetically elevated the levels of alpha-synuclein expression possible by lowering the DNA methylation status and inducing autophagic impairment in vitro and in vivo.

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.

Altered neural cell junctions and ion-channels leading to disrupted neuron communication in Parkinson's disease

Parkinson's disease (PD) is a neurological disorder that affects the movement of the human body. It is primarily characterized by reduced dopamine levels in the brain. The causative agent of PD is still unclear but it is generally accepted that α-synuclein has a central role to play. It is also known that gap-junctions and associated connexins are complicated structures that play critical roles in nervous system signaling and associated misfunctioning. Thus, our current article emphasizes how, alongside α-synuclein, ion-channels, gap-junctions, and related connexins, all play vital roles in influencing multiple metabolic activities of the brain during PD. It also highlights that ion-channel and gap-junction disruptions, which are primarily mediated by their structural-functional changes and alterations, have a role in PD. Furthermore, we discussed available drugs and advanced therapeutic interventions that target Parkinson's pathogenesis. In conclusion, it warrants creating better treatments for PD patients. Although, dopaminergic replenishment therapy is useful in treating neurological problems, such therapies are, however, unable to control the degeneration that underpins the disease, thereby declining their overall efficacy. This creates an additional challenge and an untapped scope for neurologists to adopt treatments for PD by targeting the ion-channels and gap-junctions, which is well-reviewed in the present article.

Glutamate modulation for the treatment of levodopa induced dyskinesia: a brief review of the drugs tested in the clinic

Levodopa is the standard treatment for Parkinson's disease, but its use is marred by the emergence of dyskinesia, for which treatment options remain limited. Here, we review the glutamatergic modulators that were assessed for their antidyskinetic potential in clinical trials, including N-methyl-D-aspartate (NMDA) antagonists, agonists at the glycine-binding site on NMDA receptors, metabotropic glutamate (mGlu) 4 agonists, mGlu₅ antagonists, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) antagonists and glutamate release inhibitors. Several agents that were investigated are not selective for their targets, raising uncertainty about the extent to which glutamatergic modulation contributed to their effects. Except for amantadine, the use of glutamatergic modulators for the treatment of dyskinesia in Parkinson's disease remains largely investigational, with promising results obtained with mGlu₅ negative allosteric modulation.

How I treat Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a complex neurodegenerative condition. Treatment strategies through all stages of disease progression could affect quality of life and influence the development of future complications, making it crucial for the clinician to be on top of the literature.

OBJECTIVE

This paper reviews the current treatment of PD, from early to advanced stages.

METHODS

A literature review was conducted focusing on the treatment of PD, in the different stages of progression.

RESULTS

Every individual with a new diagnosis of PD should be encouraged to start exercising regularly. In the early stage, treatment should focus on using the lowest dose of levodopa or combination therapy that provides maximum functional capacity, and does not increase the risk of complications, such as peak dose dyskinesias and impulse control disorders. At the moderate and advanced stages, motor fluctuations and complications of treatment dominate the picture, making quality of life one important issue. Rehabilitation programs can improve motor symptoms and should be offered to all patients at any stage of disease progression.

CONCLUSION

Many factors need to be considered when deciding on the best treatment strategy for PD, such as disease progression, presence of risk factors for motor and behavioral complications, potential side effects from dopaminergic therapy and phenotypical variabilities. Treatment should focus on functional capacity and quality of life throughout the whole disease course.

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.

Levodopa-induced dyskinesia: a historical review of Parkinson's disease, dopamine, and modern advancements in research and treatment

Over the past two decades, animal models of Parkinson's disease (PD) have helped to determine the plausible underlying mechanism of levo-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia following L-DOPA treatment. However, our understanding of the mechanisms related to this phenomenon remains incomplete. The purpose of this manuscript is to provide a comprehensive review of treatment protocols used for assessing the occurrence of L-DOPA-induced dyskinesia, L-DOPA absorption, distribution, drug/food interaction, and discuss current strategies and future directions. This review offers a historical perspective using L-DOPA in animal models of PD and the occurrence of L-DOPA-induced dyskinesia.

Should “on-demand” treatments for Parkinson’s disease OFF episodes be used earlier?

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OFF episodes are common in patients as Parkinson’s disease progresses.

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OFF episodes are typically managed with “ON-extenders” and changes in levodopa dosing.

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OFF episodes persist despite conventional treatment.

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“On-demand” therapies can rapidly improve OFF symptoms.

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A shift to earlier complementary use of “on-demand” therapies should be considered.

We discuss a shift in the treatment paradigm for OFF episode management in patients with Parkinson’s disease, based on clinical experience in the United States (US). Three “on-demand” treatments are currently available in the US as follows: subcutaneous apomorphine, levodopa inhalation powder, and sublingual apomorphine. We empirically propose that “on-demand” treatments can be utilized as a complementary treatment when OFF episodes emerge and can be utilized when needed rather than reserving these treatments only until other treatment approaches (adjustment of baseline treatment and/or addition of adjunctive treatment with “ON-extenders”) have failed. Current treatment approaches combine “ON-extenders” with increasing levodopa dosing and/or frequency to treat OFF episodes. Yet, OFF episodes often persist, with a substantial amount of daily OFF time. OFF episode treatment is hindered by variable gastrointestinal (GI) absorption of oral levodopa, reflecting GI dysmotility and protein competition. Novel “on-demand” treatments bypass the gut and can improve OFF symptoms more rapidly and reliably than oral levodopa. With the emergence of novel “on-demand” treatments, we conclude that a shift in treatment paradigm to the earlier, complementary use of these medications be considered.

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.

Selected natural and synthetic agents effective against Parkinson's disease with diverse mechanisms

Similar to other neurodegenerative diseases, Parkinson's disease (PD) has been extensively investigated with respect to its neuropathological background and possible treatment options. Since the symptomatic outcomes are generally related to dopamine deficiency, the current treatment strategies towards PD mainly employ dopaminergic agonists as well as the compounds acting on dopamine metabolism. These drugs do not provide disease modifying properties; therefore alternative drug discovery studies focus on targets involved in the progressive neurodegenerative character of PD. This study has aimed to present the pathophysiology of PD concomitant to the representation of drugs and promising molecules displaying activity against the validated and non-validated targets of PD.

Novel therapeutic interventions for combating Parkinson's disease and prospects of Nose-to-Brain drug delivery

Parkinson disease (PD) is a progressive neurodegenerative disorder prevalent mainly in geriatric population. While, L-DOPA remains one of the major choices for the therapeutic management of PD, various motor and non-motor manifestations complicate the management of PD. In the last two decades, exhaustive research has been carried out to explore novel therapeutic approaches for mitigating motor and non-motor symptoms of PD. These approaches majorly include receptor-based, anti-inflammatory, stem-cell and nucleic acid based. The major limitations of existing therapeutic interventions (of commonly oral route) are low efficacy due to low brain bioavailability and associated side effects. Nanotechnology has been exploited and has gained wide attention in the recent years as an approach for enhancement of bioavailability of various small molecule drugs in the brain. To address the challenges associated with PD therapy, nose-to-brain delivery utilizing nanomedicine-based approaches has been found to be encouraging in published evidence. Therefore, the present work summarises the major challenges and limitations with antiparkinsonian drugs, novel therapeutic interventions, and scope of nanomedicine-based nose-to-brain delivery in addressing the current challenges of antiparkinsonian therapy. The manuscript tries to sensitize the researchers for designing brain-targeted nanomedicine loaded with natural/synthetic scaffolds, biosimilars, and nucleic acids that can bypass the first-pass effect for the effective management of PD.

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.

Amantadine in the treatment of Parkinson's disease and other movement disorders

The efficacy of amantadine in the symptomatic treatment of patients with Parkinson's disease, discovered serendipitously more than 50 years ago, has stood the test of time and the drug is still commonly used by neurologists today. Its pharmacological actions are unique in combining dopaminergic and glutamatergic properties, which account for its dual effect on parkinsonian signs and symptoms and levodopa-induced dyskinesias. Furthermore, amantadine has additional and less well-defined pharmacological effects, including on anticholinergic and serotonergic activity. Evidence from randomised controlled trials over the past 5 years has confirmed the efficacy of amantadine to treat levodopa-induced dyskinesias in patients with Parkinson's disease, and clinical studies have also provided support for its potential to reduce motor fluctuations. Other uses of amantadine, such as in the treatment of drug-induced parkinsonism, atypical parkinsonism, Huntington's disease, or tardive dyskinesia, lack a strong evidence base. Future trials should examine its role in the management of motor and non-motor symptoms in patients with early Parkinson's disease and those with other movement disorders.

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.

Visual Hallucinations and the Role of Medications in Parkinson's Disease: Triggers, Pathophysiology, and Management

Visual hallucinations, which are part of the syndrome of Parkinson's disease (PD) psychosis, affect patients' quality of life and increase the likelihood of residential aged-care placement. The association between visual hallucinations and dopaminergic and other medications that are necessary for the symptomatic management of motor and other symptoms of PD is a common clinical dilemma. While dopaminergic medications have long been associated with PD psychosis, a clear causal link has not been established, and other neurotransmitter systems, particularly noradrenaline, serotonin, and acetylcholine, are implicated and important. A diverse range of demographic and disease-related risk factors, some being modifiable, highlight the complexity of potential underlying pathophysiological processes but also broaden practical options for prevention and treatment that can be multifaceted and individualized. The investigators reviewed the clinical features and epidemiology of visual hallucinations and PD, explored the pathological evidence for dysfunction of multiple neurotransmitter systems that may be relevant to these phenomena, and addressed the potential of medications commonly used in PD to either trigger or treat these symptoms.

Implications of dopaminergic medication withdrawal in Parkinson's disease

The trajectory of the use of dopamine replacement therapy (DRT) in Parkinson's disease (PD) is variable and doses may need to be increased, but also tapered. The plan for dose adjustment is usually done as per drug information recommendations from the licensing bodies, but there are no clear guidelines with regards to the best practice regarding the tapering off schedule given sudden dose reductions of drugs such as dopamine agonists may have serious adverse consequences. A systematic literature search was, therefore, performed to derive recommendations and the data show that there are no controlled studies or evidence-based recommendations how to taper or discontinue PD medication in a systematic manner. Most of the data were available on the dopamine agonist withdrawal syndrome (DAWS) and we found only two instructions on how to reduce pramipexole and rotigotine published by the EMA. We suggest that based on the available data, levodopa, dopamine agonists (DA), and amantadine should not be discontinued abruptly. Abrupt or sudden reduction of DA or amantadine in particular can lead to severe life-threatening withdrawal symptoms. Tapering off levodopa, COMT inhibitors, and MAO-B inhibitors may worsen motor and non-motor symptoms. Based on our clinical experience, we have proposed how to reduce PD medication and this work will form the basis of a future Delphi panel to define the recommendations in a consensus.

EASE LID 2: A 2-Year Open-Label Trial of Gocovri (Amantadine) Extended Release for Dyskinesia in Parkinson's Disease

BACKGROUND

Gocovri® (amantadine) extended release capsules are approved for the treatment of dyskinesia in patients with Parkinson's disease (PD) receiving levodopa-based therapy.

OBJECTIVE

To evaluate the long-term safety, tolerability, and efficacy of Gocovri in patients with PD experiencing levodopa-induced dyskinesia.

METHODS

In this 2-year open-label trial, patients completing double-blind Gocovri clinical trials or excluded from prior trials because of deep-brain stimulation (DBS) received Gocovri 274 mg once daily at bedtime. The primary objective was to evaluate long-term safety and tolerability. In addition, dyskinesia and OFF time were assessed using Part IV (Motor Complications) scores on the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS).

RESULTS

Among 223 enrolled patients (mean PD duration, 11.7 years; mean levodopa use, 9.3 years), 75.8% completed 1 year of treatment and 57.8% completed the trial, with a median treatment duration of 1.9 years. Common adverse events were fall (32.7%), hallucination (24.2%), peripheral edema (16.1%), constipation (13.5%), and urinary tract infection (10.3%); 31 patients (13.9%) discontinued because of adverse events considered related to study drug. At baseline, MDS-UPDRS Part IV scores were lower for patients continuing Gocovri (mean, 6.5 points) than for previous placebo (9.4) or DBS groups (10.5) but were similar for all groups by week 8 (6.3, 6.2, 6.4, respectively), and remained low for the duration of the trial (at week 100: 6.9, 7.3, 7.0, respectively).

CONCLUSIONS

In patients with PD, Gocovri showed long-term safety and tolerability consistent with double-blind trial findings, and durable reduction in motor complications (dyskinesia and OFF time).

Emerging Pharmacotherapies for Motor Symptoms in Parkinson's Disease

Parkinson's disease (PD) is the second commonest neurodegenerative disorder in the older adult and is characterized by progressive disabling motor symptoms of bradykinesia, tremor, rigidity, postural instability and also non motor symptoms that affect quality of life. The pharmacotherapy of PD consists of oral, transdermal, and subcutaneous medications, as well as invasive advanced therapies at later stages of the disease. PD medications are often started as monotherapy but with the progression of the illness often there is a need to add more medications and frequently comprises of a challenging polypharmacotherapy. Adverse effects of pharmacotherapy often add to the problems of adequate treatment. Patients and physicians have to prioritize treatment goals on the most disabling symptoms and the safest and most effective treatments. Almost every year newer medications and modes of delivery continue to be researched and added to the therapeutic armamentarium. This review article outlines existing and emerging pharmacotherapies for motor symptoms in PD.

An Update on Medical and Surgical Treatments of Parkinson's Disease

Parkinson’s disease (PD) is characterized by degeneration of dopaminergic neurons in the substantia nigra pars compacta and other neuronal populations. The worldwide prevalence of PD is over 7 million and has been increasing more rapidly than many other neurodegenerative disorders. PD symptoms can be broadly divided into motor (slowness, stiffness, tremor) and non-motor symptoms (such as depression, dementia, psychosis, orthostatic hypotension). Patients can also have prodromal symptoms of rapid eye movement sleep behavior disorder, hyposmia, and constipation. The diagnosis of PD is mainly clinical, but dopamine transporter single-photon emission computed tomography can improve the accuracy of the diagnosis. Dopamine based therapies are used for the treatment of motor symptoms. Non-motor symptoms are treated with other medications such as selective serotonin reuptake inhibitors (depression/anxiety), acetylcholinesterase inhibitors (dementia), and atypical antipsychotics (psychosis). Patients with motor fluctuations or uncontrolled tremor, benefit from deep brain stimulation. Levodopa-carbidopa intestinal gel is an alternative to deep brain stimulation for uncontrolled motor fluctuations. Rehabilitative therapies such as physical, occupational, and speech therapy are important during all stages of the disease. Management of PD is complex but there have been significant advancements in the treatment of motor and non-motor symptoms over the past few years. This review discusses the updates in the medical and surgical management of PD.

Effects of Gocovri (Amantadine) Extended-Release Capsules on Motor Aspects of Experiences of Daily Living in People with Parkinson's Disease and Dyskinesia

Introduction

Gocovri, a bedtime-administered delayed-release/extended-release capsule formulation of amantadine, is the only drug approved by the US Food and Drug Administration as levodopa-adjunctive therapy for the treatment of OFF episodes and/or dyskinesia in Parkinson’s disease (PD). Part II of the Movement Disorder Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) assesses patient-perceived disability on experiences of daily living affected by PD motor symptoms. We analyzed Gocovri-related changes in MDS-UPDRS Part II ratings in two placebo-controlled clinical trials.

Methods

Baseline to week 12 changes in MDS-UPDRS Part II total and item scores were compared for Gocovri and placebo using pooled data from phase 3 trials (EASE LID and EASE LID 3).

Results

Baseline mean MDS-UPDRS Part II total score was 15.1 for Gocovri (n = 100) and 15.3 for placebo (n = 96) groups. At week 12, the least squares mean change from baseline was −3.4 for the Gocovri group and −1.4 for placebo (treatment difference, −2.0; 95% CI −3.3 to −0.7; P = 0.004). For Gocovri, change from baseline exceeded a published minimal clinically important difference threshold of 3.05. Gocovri-related treatment differences over placebo were driven primarily by improvement in the scale items of freezing (−0.4; P < 0.0001), tremor (−0.4; P = 0.002), getting out of bed/car/deep chair (−0.3; P = 0.002), and eating tasks (−0.2; P = 0.016).

Conclusion

In addition to improvement in dyskinesia, Gocovri-treated participants experienced improvement in motor aspects of experiences of daily living. Analyses suggest that Gocovri may specifically improve freezing, tremor, getting out of bed/car/deep chair, and eating tasks.

Trial Registration

ClinicalTrials.gov identifiers: NCT02136914, NCT02274766.

Pathophysiological Mechanisms and Experimental Pharmacotherapy for L-Dopa-Induced Dyskinesia

L-dopa-induced dyskinesia (LID) is the most frequent motor complication associated with chronic L-dopa treatment in Parkinson’s disease (PD). Recent advances in the understanding of the pathophysiological mechanisms underlying LID suggest that abnormalities in multiple neurotransmitter systems, in addition to dopaminergic nigrostriatal denervation and altered dopamine release and reuptake dynamics at the synaptic level, are involved in LID development. Increased knowledge of neurobiological LID substrates has led to the development of several drug candidates to alleviate this motor complication. However, with the exception of amantadine, none of the pharmacological therapies tested in humans have demonstrated clinically relevant beneficial effects. Therefore, LID management is still one of the most challenging problems in the treatment of PD patients. In this review, we first describe the known pathophysiological mechanisms of LID. We then provide an updated report of experimental pharmacotherapies tested in clinical trials of PD patients and drugs currently under study to alleviate LID. Finally, we discuss available pharmacological LID treatment approaches and offer our opinion of possible issues to be clarified and future therapeutic strategies.

Roles of the Functional Interaction between Brain Cholinergic and Dopaminergic Systems in the Pathogenesis and Treatment of Schizophrenia and Parkinson's Disease

Most physiologic processes in the brain and related diseases involve more than one neurotransmitter system. Thus, elucidation of the interaction between different neurotransmitter systems could allow for better therapeutic approaches to the treatments of related diseases. Dopaminergic (DAergic) and cholinergic neurotransmitter system regulate various brain functions that include cognition, movement, emotion, etc. This review focuses on the interaction between the brain DAergic and cholinergic systems with respect to the pathogenesis and treatment of schizophrenia and Parkinson’s disease (PD). We first discussed the selection of motor plans at the level of basal ganglia, the major DAergic and cholinergic pathways in the brain, and the receptor subtypes involved in the interaction between the two signaling systems. Next, the roles of each signaling system were discussed in the context of the negative symptoms of schizophrenia, with a focus on the α7 nicotinic cholinergic receptor and the dopamine D₁ receptor in the prefrontal cortex. In addition, the roles of the nicotinic and dopamine receptors were discussed in the context of regulation of striatal cholinergic interneurons, which play crucial roles in the degeneration of nigrostriatal DAergic neurons and the development of L-DOPA-induced dyskinesia in PD patients. Finally, we discussed the general mechanisms of nicotine-induced protection of DAergic neurons.

Effects of Gocovri (Amantadine) Extended Release Capsules on Non-Motor Symptoms in Patients with Parkinson's Disease and Dyskinesia

Introduction

Gocovri (amantadine) extended release capsules are approved for treatment of dyskinesia and as a levodopa adjunct for OFF episodes in patients with Parkinson’s disease (PD). We report treatment-related effects on non-motor symptoms (NMS) assessed as secondary outcomes in two trials using the Movement Disorder Society–Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) Part I.

Methods

EASE LID and EASE LID 3 enrolled levodopa-treated patients with PD and ≥ 1 h/day ON time with troublesome dyskinesia. Patients were randomized to Gocovri (274 mg) or placebo taken daily at bedtime. Treatment differences from baseline to week 12 in MDS-UPDRS Part I were evaluated for the pooled population (N = 196) from both trials. Correlation analyses of NMS (MDS-UPDRS Part I) with dyskinesia using Unified Dyskinesia Rating Scale (UDysRS) scores were performed.

Results

For changes in the MDS-UPDRS Part I items, the treatment difference favored Gocovri in daytime sleepiness (P = 0.006) and depression (P = 0.049) scores, but favored placebo in cognitive impairment (P = 0.038), and  hallucinations and psychosis (P < 0.001) scores. The treatment difference for the changes in total Part I score was −0.8, favoring Gocovri (P = 0.22). At baseline, MDS-UPDRS Part I modestly correlated with UDysRS score (r +0.25, P < 0.001), and improvement in NMS correlated with improvement in dyskinesia at week 12 for Gocovri (r +0.39, P < 0.001) but not placebo (r +0.12, P = 0.29). The most commonly reported adverse events for Gocovri were hallucination (21%); dizziness, dry mouth, and peripheral edema (16% each); and constipation, falls, and orthostatic hypotension (13% each).

Conclusion

This post hoc analysis shows potential benefit with Gocovri treatment for the NMS of daytime sleepiness and depression in dyskinetic PD patients. Overall, improvement in NMS scores correlated with improvement in dyskinesia.

Trial Registration

ClinicalTrials.gov identifiers: NCT02136914 and NCT02274766

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

Background: Clinical trials for antiparkinsonian drugs aimed at managing motor complications typically use patient diaries to divide levodopa-induced dyskinesias (LID) into "troublesome" and "non-troublesome" categories. Yet, given the choice, most patients would prefer to live without experiencing any dyskinesia. However, the concept of evaluating time spent ON without any dyskinesia as an outcome has never been tested. We conducted analyses of pooled Gocovri pivotal trial data in order to evaluate the extent to which Gocovri increased the time PD patients spent ON without dyskinesia (troublesome or non-troublesome), beyond its already identified improvement in reducing troublesome dyskinesia. Methods: Patients enrolled in phase 3 trials (EASE LID [NCT02136914] or EASE LID 3 [NCT02274766]) recorded time spent in the following PD diary states at baseline and Week 12 (endpoint): asleep, OFF, ON with troublesome dyskinesia, ON with non-troublesome dyskinesia, and ON without dyskinesia. Mixed model repeated measures analyses with estimated Cohen D effect sizes were performed on the modified intent to treat population to evaluate changes in time spent in these states. Results: Patients randomized to receive Gocovri showed an increase in ON time without dyskinesia and corresponding decreases in ON time with dyskinesia and OFF time vs. placebo. Treatment effects were statistically significant for Gocovri vs. placebo starting at Week 2 and were sustained until Week 12. On MMRM analysis at Week 12, patients in the Gocovri group showed an adjusted mean ± SE increase over placebo of 2.9 ± 0.6 h in ON time without dyskinesia (Cohen D effect size 0.79) and an adjusted mean ± SE decrease of -1.9 ± 0.6 h in ON time with dyskinesia (troublesome + non-troublesome) (Cohen D effect size 0.49), that included a -1.5 ± 0.4 h placebo-adjusted reduction in ON time with troublesome dyskinesia and a -0.6 ± 0.4 h reduction in ON time with non-troublesome dyskinesia. OFF time was reduced by -1.0 ± 0.3 h compared to placebo. Conclusions: Gocovri treatment more than doubled the daily time patients spent ON without dyskinesia. These results suggest that the Gocovri treatment effect was driven by a reduction in overall motor complications including ON time with both troublesome and non-troublesome dyskinesia as well as time spent OFF.

Istradefylline - a first generation adenosine A2A antagonist for the treatment of Parkinson's disease

Introduction It is now accepted that Parkinson's disease (PD) is not simply due to dopaminergic dysfunction, and there is interest in developing non-dopaminergic approaches to disease management. Adenosine A_2A receptor antagonists represent a new way forward in the symptomatic treatment of PD.Areas covered In this narrative review, we summarize the literature supporting the utility of adenosine A_2A antagonists in PD with a specific focus on istradefylline, the most studied and only adenosine A_2A antagonist currently in clinical use.Expert opinion: At this time, the use of istradefylline in the treatment of PD is limited to the management of motor fluctuations as supported by the results of randomized clinical trials and evaluation by Japanese and USA regulatory authorities. The relatively complicated clinical development of istradefylline was based on classically designed studies conducted in PD patients with motor fluctuations on an optimized regimen of levodopa plus adjunctive dopaminergic medications. In animal models, there is consensus that a more robust effect of istradefylline in improving motor function is produced when combined with low or threshold doses of levodopa rather than with high doses that produce maximal dopaminergic improvement. Exploration of istradefylline as a 'levodopa sparing' strategy in earlier PD would seem warranted.

Update on Parkinson's Disease Therapy

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Development, Efficacy and Safety of Once-daily, Bedtime, Extended-release Amantadine (Gocovri®) to Treat Dyskinesia and OFF Time in Parkinson’s Disease

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