Therapeutic Strategies to Treat or Prevent Off Episodes in Adults with Parkinson's Disease

Targeting phosphodiesterase 4 as a potential therapy for Parkinson's disease: a review

Phosphodiesterases (PDEs) have become a promising therapeutic target for various disorders. PDEs are a vast and diversified family of enzymes that degrade cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which have several biochemical and physiological functions. Phosphodiesterase 4 (PDE4) is the most abundant PDE in the central nervous system (CNS) and is extensively expressed in the mammalian brain, where it catalyzes the hydrolysis of intracellular cAMP. An alteration in the balance of PDE4 and cAMP results in the dysregulation of different biological mechanisms involved in neurodegenerative diseases. By inhibiting PDE4 with drugs, the levels of cAMP inside the cells could be stabilized, which may improve the symptoms of mental and neurological disorders such as memory loss, depression, and Parkinson's disease (PD). Though numerous studies have shown that phosphodiesterase 4 inhibitors (PDE4Is) are beneficial in PD, there are presently no approved PDE4I drugs for PD. This review presents an overview of PDE4Is and their effects on PD, their possible underlying mechanism in the restoration/protection of dopaminergic cell death, which holds promise for developing PDE4Is as a treatment strategy for PD. Methods on how these drugs could be effectively delivered to develop as a promising treatment for PD have been suggested.

Cerium oxide nanoparticles modulating the Parkinson's disease conditions: From the alpha synuclein structural point of view and antioxidant properties of cerium oxide nanoparticles

Parkinson's and Alzheimer's disease is the main cause of dementia, which is associated with the progressive deterioration of the intelligence and senses. Free radicals are created during oxidative stress in cells, which are considered one of the destructive factors in neurodegenerative diseases. In this study, the antifibrillar and antioxidant properties of cerium oxide nanoparticles (CeO2 NPs) were investigated experimentally and theoretically. The CeO2 NPs were synthesized and analyzed to reveal the physicochemical and biological properties. The results showed that the CeO2 NPs have unique properties with potent antioxidant activities. The experimental and computational studies showed that the CeO2 NPs interact with the active site of Alpha-synuclein. The existence of hydrogen bonding between O atoms of CeO2 NPs and N-H of adjacent acid amines and the equilibrium distances were confirmed by 1.751 (Leu100), 1.786 (Gln99) and 2.213 Å (Lys97). The minimum free energy binding of L-DOPA drug (as positive control) and CeO2 NPs were negative, resulting interaction between compounds and protein. As a result, these compounds inhibited Alpha-synuclein protein aggregation. In addition, that CeO2 NPs strongly binds with receptor by relative binding energy as compared with L-DOPA drug. These findings revealed that CeO2 NPs prevent Alpha-synuclein fibrillation and can be applied as nano-drug against the Parkinson's disease.

Deep brain stimulation in PD: risk of complications, morbidity, and hospitalizations: a systematic review

Introduction

Parkinson's disease (PD) is a progressive and debilitating neurological disorder. While dopaminergic medication improves PD symptoms, continued management is complicated by continued symptom progression, increasing medication fluctuations, and medication-related dyskinesia. Deep brain stimulation (DBS) surgery is a well-accepted and widespread treatment often utilized to address these symptoms in advanced PD. However, DBS may also lead to complications requiring hospitalization. In addition, patients with PD and DBS may have specialized care needs during hospitalization.

Methods

This systematic review seeks to characterize the complications and risk of hospitalization following DBS surgery. Patient risk factors and modifications to DBS surgical techniques that may affect surgical risk are also discussed.

Results

It is found that, when candidates are carefully screened, DBS is a relatively low-risk procedure, but rate of hospitalization is somewhat increased for DBS patients.

Discussion

More research is needed to determine the relative influence of more advanced disease vs. DBS itself in increased rate of hospitalization, but education about DBS and PD is important to insure effective patient care within the hospital.

The Administration of Levodopa in a Patient With Parkinson's Disease Using a Novel Maxillofacial Route: A First-in-Human Report

Parkinson's disease is characterized by the loss of nigrostriatal dopaminergic neurons in the brain. Dopamine cannot be administered systemically because it does not cross the blood-brain barrier. Oral levodopa remains the gold standard to date. Currently, for patients who show a poor response to oral levodopa and for those who cannot take it orally, the alternate routes available are inhalation and continuous administration via intestinal and subcutaneous routes. In this report, a novel maxillofacial route was used for the first time in the world to administer levodopa to a Parkinson's patient. Furthermore, the efficacy of maxillofacial administration was compared with the oral route of administration.

Inhaled levodopa for threatening impending OFF episodes in managing Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder that leads to the degeneration of dopaminergic neurons resulting in a widespread pathology of motor and non-motor symptoms. Oral levodopa remains the most effective symptomatic treatment of PD, but motor complications such as Off episodes occur over time. The spectrum of manifestation of OFF episodes varies, e.g., early morning akinesia, end-of-dose wearing OFF, delayed ON, suboptimal ON and dose failure. The functional disability substantially impacts the quality of life for PD patients. An innovative on-demand therapy to treat Off episodes was approved for patients receiving oral levodopa/dopa deacarboxylase inhibitor: inhaled levodopa powder (Inbrija®). The pulmonary delivery of inhaled levodopa powder provides a predictable and fast treatment effect, independent of gastrointestinal dysfunctions or food intake, which could affect levodopa absorption. Levodopa is administered with a breath-actuated inhaler device and the approved dose is 84 mg per Off episode. During the pivotal SPAN-PD phase III trial, significant improvement in Unified Parkinson Disease Rating Scale III score was measured 30 min post-dose at week 12. Improvement was already seen for the first measured time point 10 min post-dose. No differences in pulmonary function was observed when using inhaled levodopa powder regularly for up to 12 months. Inhaled levodopa powder was also approved for early morning Off episodes. The aim of this review article is to give an overview of the different clinical studies of the innovative inhaled levodopa powder, a new on-demand therapy to treat Off episodes in PD.

Effective Management of "OFF" Episodes in Parkinson's Disease: Emerging Treatment Strategies and Unmet Clinical Needs

Motor complications related to the chronic administration of levodopa and failure to prevent the neurodegenerative disease process counterbalance the pivotal discovery of levodopa as the cornerstone of PD treatment. Excellent motor control is offered early during the course of treatment, but this diminishes as pathological changes in the striatum lead to synaptic dopamine levels becoming completely dependent on exogenous dopamine. This non-physiologic stimulation of dopamine receptors eventually manifests as OFF episodes. As no disease modifying therapy exists for PD that can disrupt these pathological changes, most research and treatment focuses on optimization of dopaminergic stimulation of striatal receptors so that they mimic tonic, physiologic stimulation as closely as possible. Strategies focusing on these challenges have included non-pharmacologic approaches, optimizing levodopa pharmacokinetics, using adjunctive treatments including those with non-dopaminergic mechanisms, and implementing rescue therapies. Device aided therapies, including surgery, are also available. In this review, we will focus on effective management of motor symptoms related to OFF periods, including emerging strategies. Unmet clinical needs will be discussed, including non-motor symptoms, targeted molecular therapies and disease modifying therapy.

Why do 'OFF' periods still occur during continuous drug delivery in Parkinson's disease?

Continuous drug delivery (CDD) is used in moderately advanced and late-stage Parkinson’s disease (PD) to control motor and non-motor fluctuations (‘OFF’ periods). Transdermal rotigotine is indicated for early fluctuations, while subcutaneous apomorphine infusion and levodopa-carbidopa intestinal gel are utilised in advanced PD. All three strategies are considered examples of continuous dopaminergic stimulation achieved through CDD. A central premise of the CDD is to achieve stable control of the parkinsonian motor and non-motor states and avoid emergence of ‘OFF’ periods. However, data suggest that despite their efficacy in reducing the number and duration of ‘OFF’ periods, these strategies still do not prevent ‘OFF’ periods in the middle to late stages of PD, thus contradicting the widely held concepts of continuous drug delivery and continuous dopaminergic stimulation. Why these emergent ‘OFF’ periods still occur is unknown. In this review, we analyse the potential reasons for their persistence. The contribution of drug- and device-related involvement, and the problems related to site-specific drug delivery are analysed. We propose that changes in dopaminergic and non-dopaminergic mechanisms in the basal ganglia might render these persistent ‘OFF’ periods unresponsive to dopaminergic therapy delivered via CDD.

Zonisamide's Efficacy and Safety on Parkinson's Disease and Dementia with Lewy Bodies: A Meta-Analysis and Systematic Review

Objective

Clinical data has recently shown an association between Parkinson's disease (PD), Dementia with Lewy bodies (DLB), and zonisamide. The purpose of this study was to thoroughly evaluate the efficacy and safety of zonisamide in PD and DLB.

Methods

Pubmed, the Cochrane Library, Web of Science, and Embase databases were searched for all randomized clinical trials (RCTS) on the role of zonisamide in PD and DLB that were completed by April 18, 2022. UPDRS II (off) total score, UPDRS III total score, Daily "off" time, and UPDRS Part IV, Nos. 32, 33, and 34 were used as clinical efficacy endpoints. Adverse events reported in the RCTs will be considered in the final safety analysis. To better understand the effect of zonisamide on the efficacy and safety of PD and DLB, the UPDRS III total score and the six overlapping adverse events were examined in subgroups. Either a fixed effects model analysis (OR) or a random effects model analysis (MD) is used to figure out the mean difference (MD) and the relative risk.

Results

Seven articles involving 1749 patients (916 PD and 833 DLB) were included in this study. Compared to the control group, zonisamide could significantly reduce the UPDRS III total score in patients with PD and DLB (WMD-2.27 [95% CI: -3.06, -1.48], p < 0.0001). For patients with PD, compared to the control group, zonisamide could significantly reduce the UPDRS II (off) total score (WMD-0.81 [95% CI: -1.36, -0.26], p = 0.004), daily "off" time (WMD-0.67 [95% CI: -1.10, 0.24], p = 0.002), and UPDRS part IV, No. 32 worsen (OR-3.48 [95% CI: 1.20, 10.10], p = 0.02). In terms of safety, compared with the control group, for patients with DLB, zonisamide could significantly increase the incidence of contusion (OR-0.60 [95% CI: 0.38, 0.96], p = 0.03) and may increase the probability of reduced appetite (OR-3.13 [95% CI: 1.61, 6.08], p = 0.0008). And for patients with PD, zonisamide may increase the probability of somnolence (OR-2.17 [95% CI: 1.25, 3.76], p = 0.006).

Conclusions

For the analysis of the current study results, our results show that zonisamide could improve the motor function in patients with PD and DLB and improve the activities of daily living (off) and wearing off and decrease the duration of dyskinesia in patients with PD. In terms of safety, the use of zonisamide significantly increases the probability of contusion in patients with DLB and may increase the probability of reduced appetite in patients with DLB and somnolence in patients with PD. Zonisamide appears to be a new treatment option for patients with PD and DLB. However, the effectiveness and safety of zonisamide in the treatment of PD and DLB need to be further investigated.

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.

Closing the loop for patients with Parkinson disease: where are we?

Although levodopa remains the most efficacious symptomatic therapy for Parkinson disease (PD), management of levodopa treatment during the advanced stages of the disease is extremely challenging. This difficulty is a result of levodopa's short half-life, a progressive narrowing of the therapeutic window, and major inter-patient and intra-patient variations in the dose-response relationship. Therefore, a suitable alternative to repeated oral administration of levodopa is being sought. Recent research efforts have focused on the development of novel levodopa delivery strategies and wearable physical sensors that track symptoms and disease progression. However, the need for methods to monitor the levels of levodopa present in the body in real time has been overlooked. Advances in chemical sensor technology mean that the development of wearable and mobile biosensors for continuous or frequent levodopa measurements is now possible. Such levodopa monitoring could help to deliver personalized and timely medication dosing to alleviate treatment-related fluctuations in the symptoms of PD. Therefore, with the aim of optimizing therapeutic management of PD and improving the quality of life of patients, we share our vision of a future closed-loop autonomous wearable 'sense-and-act' system. This system consists of a network of physical and chemical sensors coupled with a levodopa delivery device and is guided by effective big data fusion algorithms and machine learning methods.

Scanning Imaging Study of Patients with Parkinson's Disease Lower Urinary Tract Dysfunction Based on Linear Equation

A predictive method based on a linear equation was proposed to study the factors influencing lower urinary tract dysfunction in Parkinson's disease. A 10-month follow-up of 200 selected Parkinson's patients from January to December 2020 used a linear regression equation to analyze whether depletion function was associated with a specific nonmotor function loss, and a linear regression equation was used for analysis. A loss of emptiness function was used to determine whether there are complications associated with lower motor function and cognitive function. The experimental results showed that dysuria in Parkinson's disease was related to the following nonmotility disorders: gastrointestinal dysfunction (OR 2.52, 95% CI 1.57-3.92, P < 0.001), cardiovascular dysfunction (OR 2.31, 95% CI 1.23~4.11, P = 0.014), respiratory dysfunction (OR 1.72, 95% CI 1.32~3.24, P = 0.029), cutaneous autonomic dysfunction (OR 1.91, 95% CI 1.15~3.08, P = 0.023), and sleep disorders (OR 2.01, 95% CI 1.32~3.14, P = 0.001). In addition, dysuria was associated with higher UPDRS-III (regression coefficient 1.74, 95% CI 0.56-2.67, P = 0.001). Thus, nonmotor disorders have been shown to be associated with early impairment.

Cost-effectiveness analysis of the Parkinson's KinetiGraph and clinical assessment in the management of Parkinson's disease

AIMS

The Parkinson's KinetiGraph (PKG) is a wrist-worn movement recording system that collates continuous, objective, data during daily activities in people with Parkinson's disease (PD) providing a report for clinicians. This study explores the cost-effectiveness of adding the PKG to routine PD assessments.

METHODS

A de novo Markov model of three health states: uncontrolled, controlled and death compared PKG plus routine assessment by a Movement Disease Specialist (MDS) versus routine assessment. Uncontrolled and controlled states were based on the Movement Disorder Society - Unified Parkinson's Disease Rating Scale (MDS-UPDRS) II and III scores. The transition between health states was dependent on improvement in MDS-UPDRS II and III, and transition to death state on all cause-mortality and PD-specific relative mortality risk. Markov cycle length was yearly beyond year 1 and lifetime horizon 22 years.

LIMITATIONS

PKG evidence incorporated in this analysis is based on findings from one clinical trial. Health state utilities were mapped and the probability of patients progressing from uncontrolled to controlled health state at the second visit and beyond was derived from a bootstrap method which assumed a normal distribution for MDS-UPDRS.

RESULTS

The addition of the PKG to usual PD assessments is a cost-effective intervention. PKG plus routine assessment is associated with lower total costs compared to routine assessment (£141,950 versus £159,312) and improved quality-adjusted life years (7.88 versus 7.61), resulting in an incremental cost-effectiveness ratio of -£64,978.99 and a net monetary benefit of £22,706.37 using a £20,000 threshold. Results were robust across sensitivity and scenario analyses.

CONCLUSIONS

Management of PD involves monitoring and evaluation of symptoms to assess disease progression and ensure appropriate treatment choices. Adding the PKG to clinical assessment in routine care allows for improved and objective identification of PD motor symptoms which can be used in clinical decision making to improve patient outcomes.

Zonisamide improves wearing off in Parkinson's disease without exacerbating dyskinesia: Post hoc analysis of phase 2 and phase 3 clinical trials

INTRODUCTION

Although phase 2 and 3 clinical trials in Japan showed that zonisamide improved wearing off in patients with Parkinson's disease (PD), no studies to date have evaluated whether zonisamide improves wearing off in patients with PD without exacerbating dyskinesia. Therefore, we examined this hypothesis in a post hoc analysis of pooled data from the previous phase 2 and 3 trials.

METHODS

Both trials evaluated zonisamide 25 mg and 50 mg versus placebo during a 12-week treatment period. In our analysis, primary efficacy variables were adjusted mean change in wearing off (evaluated as change in "off" time) and dyskinesia from baseline to 12 weeks. Dyskinesia was evaluated using Unified Parkinson's Disease Rating Scale (UPDRS) part 4 items 32 (4-32; duration of dyskinesia) and 33 (4-33; disability of dyskinesia) score. Criteria outcomes included rates of patients meeting specific criteria based on off time plus UPDRS part 4-32 or 4-33.

RESULTS

A total of 212 patients were included in this analysis. Zonisamide 50 mg significantly reduced off time and UPDRS part 4-33 score at week 12 versus placebo without increasing UPDRS part 4-32 score. The proportion of patients receiving zonisamide 50 mg who met the criterion "Off time decreased and UPDRS part 4-33 score did not increase" was significantly higher than that of patients receiving placebo.

CONCLUSION

Zonisamide improves wearing off without exacerbating dyskinesia in Japanese patients with PD. Moreover, zonisamide 50 mg may improve dyskinesia. Further studies are needed to prospectively determine the benefits and clinical relevance of zonisamide on dyskinesia.

Istradefylline Versus Opicapone for "Off" Episodes in Parkinson's Disease: A Systematic Review and Meta-Analysis

Background:

In recent times, the US-FDA approved istradefylline and opicapone as an adjunct to levodopa/carbidopa for managing the "off" episodes in Parkinson’s disease.

Purpose:

Current meta-analysis was performed to determine the safety and efficacy of these drugs in the management of “off” episodes and to recognize which among them would provide therapeutic benefits clinically.

Methods:

A thorough literature search was performed through the Cochrane Library, PubMed, and clinicaltrials.gov for a period from January 2003 to October 2020, with the following keywords: Istradefylline, KW-6002, opicapone, BIA 9-1067, and Parkinson’s disease. Those randomized, double-blind placebo/active comparator-controlled trials that analyzed the efficacy and safety of istradefylline and opicapone and that were published in the English language were included. In this analysis, the outcomes focused on the least square mean change in “off” time and Unified Parkinson’s Disability Rating Scale (UPDRS) III score from baseline to the end of the study, and the incidence of treatment-emergent adverse events (TEAEs) and dyskinesia.

Results:

Both drugs have shown significant reduction in “off” time duration (mean difference [MD] = –0.70; 95% CI [–1.11, –0.30]; P < 0.001 for istradefylline and MD = –0.85; 95% CI [–1.09, –0.61]; P < .001 for opicapone). Istradefylline showed significant improvement in UPDRS III (MD = –1.56; 95% CI [–2.71, –0.40]; P < .008), but the same was not observed with opicapone (MD = –0.63; 95% CI [–1.42, –0.15]; P < .12). The incidence of TEAEs and dyskinesia reportedly were higher in the intervention group rather than with the placebo, (risk ratio RR =1.11, 95% CI [1.02,1.20] for istradefylline and RR =1.12, 95% CI [1.00,1.25] for opicapone, and for dyskinesia particularly, the incidence was higher with opicapone as compared to istradefylline (RR = 3.47, 95% CI [2.17, 5.57], and RR = 1.77, 95% CI [1.29, 2.44], respectively).

Conclusions:

Both drugs were comparable in efficacy; however, istradefylline seemed to be better in reducing the UPDRS III score. Although the incidence of TEAEs and dyskinesia were higher with both the drugs, the incidence of dyskinesia was more in the opicapone group.

l-Theanine ameliorates motor deficit, mitochondrial dysfunction, and neurodegeneration against chronic tramadol induced rats model of Parkinson's disease

Parkinson's disease (PD) is the second most prevalent progressive neurodegenerative disease, characterized by loss of dopaminergic neurons in substantia nigra, with deficiency of dopamine in the striatum. Tramadol is safe analgesic but long-term use confirmed to elevate oxidative stress, neuroinflammation, mitochondrial dysfunction, in brain leads to motor deficits. l-Theanine is an active constituent of green tea which prevents neuronal loss, mitochondrial failure and improves dopamine, gamma-aminobutyric acid (GABA), serotonin levels and in the central nervous system (CNS) via antioxidant, anti-inflammatory, and neuromodulatory properties. In the present study, tramadol was injected intraperitoneally to Wister rats for 28 days at a dose of 50 mg/kg. l-Theanine (25, 50, and 100 mg/kg) was administered orally 3 h before tramadol administration from day 14 to day 28. Behavioral analyses including rotarod, narrow beam walk, open field, and grip strength were used to evaluate motor coordination on a weekly basis. On the day 29, all Wistar rats were sacrificed and striatum homogenates were used for biochemical (lipid peroxidation, nitrite, glutathione, glutathione peroxidase activity, superoxide dismutase, catalase, mitochondrial complex I, IV, and cyclic adenosine monophosphate), neuroinflammatory markers (tumor necrosis factor-α, interleukin-1β, and interleukin-17), and neurotransmitters (dopamine, norepinephrine, serotonin, GABA, and glutamate) analysis. Chronic tramadol treatment caused motor deficits reduced antioxidant enzymes level, increased striatal proinflammatory cytokines release, dysbalanced neurotransmitters, and reduced mitochondrial complex activity I, IV, and cAMP activity. However, l-theanine administration attenuated behavioral, biochemical, neuroinflammatory, neurotransmitters, and mitochondrial activity indicated it as a promising neuroprotective potential against degenerative changes in experimental model of PD.

Exenatide once weekly over 2 years as a potential disease-modifying treatment for Parkinson's disease: protocol for a multicentre, randomised, double blind, parallel group, placebo controlled, phase 3 trial: The 'Exenatide-PD3' study

INTRODUCTION

Parkinson's disease (PD) is a common neurodegenerative disorder with substantial morbidity. No disease-modifying treatments currently exist. The glucagon like peptide-1 receptor agonist exenatide has been associated in single-centre studies with reduced motor deterioration over 1 year. The aim of this multicentre UK trial is to confirm whether these previous positive results are maintained in a larger number of participants over 2 years and if effects accumulate with prolonged drug exposure.

METHODS AND ANALYSIS

This is a phase 3, multicentre, double-blind, randomised, placebo-controlled trial of exenatide at a dose of 2 mg weekly in 200 participants with mild to moderate PD. Treatment duration is 96 weeks. Randomisation is 1:1, drug to placebo. Assessments are performed at baseline, week 12, 24, 36, 48, 60, 72, 84 and 96 weeks.The primary outcome is the comparison of Movement Disorders Society Unified Parkinson's Disease Rating Scale part 3 motor subscore in the practically defined OFF medication state at 96 weeks between participants according to treatment allocation. Secondary outcomes will compare the change between groups among other motor, non-motor and cognitive scores. The primary outcome will be reported using descriptive statistics and comparisons between treatment groups using a mixed model, adjusting for baseline scores. Secondary outcomes will be summarised between treatment groups using summary statistics and appropriate statistical tests to assess for significant differences.

ETHICS AND DISSEMINATION

This trial has been approved by the South Central-Berkshire Research Ethics Committee and the Health Research Authority. Results will be disseminated in peer-reviewed journals, presented at scientific meetings and to patients in lay-summary format.

TRIAL REGISTRATION NUMBERS

NCT04232969, ISRCTN14552789.

Traumatic Brain Injury: Mechanistic Insight on Pathophysiology and Potential Therapeutic Targets

Traumatic brain injury (TBI) causes brain damage, which involves primary and secondary injury mechanisms. Primary injury causes local brain damage, while secondary damage begins with inflammatory activity followed by disruption of the blood-brain barrier (BBB), peripheral blood cells infiltration, brain edema, and the discharge of numerous immune mediators including chemotactic factors and interleukins. TBI alters molecular signaling, cell structures, and functions. Besides tissue damage such as axonal damage, contusions, and hemorrhage, TBI in general interrupts brain physiology including cognition, decision-making, memory, attention, and speech capability. Regardless of the deep understanding of the pathophysiology of TBI, the underlying mechanisms still need to be assessed with a desired therapeutic agent to control the consequences of TBI. The current review gives a brief outline of the pathophysiological mechanism of TBI and various biochemical pathways involved in brain injury, pharmacological treatment approaches, and novel targets for therapy.

The Future of Incretin-Based Approaches for Neurodegenerative Diseases in Older Adults: Which to Choose? A Review of their Potential Efficacy and Suitability

The current treatment options for neurodegenerative diseases in older adults rely mainly on providing symptomatic relief. Yet, it remains imperative to identify agents that slow or halt disease progression to avoid the most disabling features often associated with advanced disease stages. A potential overlap between the pathological processes involved in diabetes and neurodegeneration has been established, raising the question of whether incretin-based therapies for diabetes may also be useful in treating neurodegenerative diseases in older adults. Here, we review the different agents that belong to this class of drugs (GLP-1 receptor agonists, dual/triple receptor agonists, DPP-4 inhibitors) and describe the data supporting their potential role in treating neurodegenerative conditions including Parkinson's disease and Alzheimer's disease. We further discuss whether there are any distinctive properties among them, particularly in the context of safety or tolerability and CNS penetration, that might facilitate their successful repurposing as disease-modifying drugs. Proof-of-efficacy data will obviously be of the greatest importance, and this is most likely to be demonstrable in agents that reach the central nervous system and impact on neuronal GLP-1 receptors. Additionally, however, the long-term safety and tolerability (including gastrointestinal side effects and unwanted weight loss) as well as the route of administration of this class of agents may also ultimately determine success and these aspects should be considered in prioritising which approaches to subject to formal clinical trial evaluations.

Opicapone: A Review in Parkinson's Disease

Oral opicapone (Ongentys^®), a potent third-generation, peripheral catechol-O-methyltransferase (COMT) inhibitor, is approved as adjunctive therapy to preparations of levodopa/dopa-decarboxylase inhibitor (L-dopa/DDCI) in adults with Parkinson's disease (PD) and end-of dose (EoD) motor fluctuations. In pivotal global trials (BIPARK 1 and BIPARK 2; 14-15 weeks' duration), open-label extensions (OLEs) of BIPARK, and in the real-world setting (OPTIPARK; 3-6 months), opicapone 50 mg once daily was an effective and generally well tolerated adjunctive therapy to L-dopa/DDCI plus other PD therapy in adults with PD and EoD motor fluctuations. Adjunctive opicapone provided better efficacy than placebo for improvements in ON- and OFF-state time and fulfilled noninferiority to adjunctive entacapone for improvements in OFF time in BIPARK 1. These beneficial effects of adjunctive opicapone on motor fluctuations were maintained during 1 year of treatment in OLE studies. Given its efficacy and safety profile, adjunctive opicapone remains an important option in the management of adults with PD and EoD motor fluctuations who cannot be stabilized on preparations of L-dopa/DDCI.

Patient Preferences for Treating "OFF" Episodes in Parkinson's Disease: A Discrete Choice Experiment

INTRODUCTION

Several on-demand treatments are available for management of "OFF" episodes in patients with Parkinson's disease (PD). We evaluated patients' preferences for features of theoretical on-demand treatment options.

METHODS

In a discrete choice experiment, US adults with self-reported PD of ≥5 years, or <5 years with "OFF" episodes, taking oral carbidopa/levodopa, selected between pairs of theoretical on-demand treatments that varied by mode of administration (with and without mode-specific adverse events [AEs]), time to FULL "ON," duration of "ON," and out-of-pocket cost for a 30-day supply. Data were analyzed with a random parameters logit model; results were used to calculate relative importance of treatment attributes, preference shares, and willingness to pay.

RESULTS

Among 300 respondents, 98% had "OFF" episodes. Across the range of attribute levels included in the survey, avoiding $90 cost was most important to respondents, followed by a preferable mode of administration with associated AEs and decreasing time to FULL "ON." Duration of "ON" was relatively less important. On average, respondents preferred a theoretical dissolvable sublingual film versus other theoretical treatments with alternative modes of administration. Respondents were willing to pay $28-$52 US dollars to switch from least- to more-preferred mode of administration with associated AEs, $58 to reach FULL "ON" in 15 versus 60 min, and $9 to increase duration of FULL "ON" from 1 to 2 h.

CONCLUSION

Respondents with PD valued lower out-of-pocket cost and a sublingual mode of administration with its associated AEs when choosing an on-demand treatment for "OFF" episodes.

Istradefylline to Treat Patients with Parkinson's Disease Experiencing "Off" Episodes: A Comprehensive Review

Parkinson’s disease (PD) is a common neurodegenerative disorder that leads to significant morbidity and disability. PD is caused by a loss of dopaminergic, cholinergic, serotonergic, and noradrenergic neurons in the central nervous system (CNS), and peripherally; the syndromic parkinsonism symptoms of movement disorder, gait disorder, rigidity and tremor are mostly driven by the loss of these neurons in the basal ganglia. Unfortunately, a significant proportion of patients taking levodopa, the standard of care treatment for PD, will begin to experience a decrease in effectiveness at varying times. These periods, referred to as “off episodes”, are characterized by increased symptoms and have a detrimental effect on quality of life and disability. Istradefylline, a novel adenosine A2A receptor antagonist, is indicated as a treatment addition to levodopa/carbidopa in patients experiencing “off episodes”. It promotes dopaminergic activity by antagonizing adenosine in the basal ganglia. This review will discuss istradefylline as a treatment for PD patients with off episodes.

Parkinson's disease: etiopathogenesis and treatment

The concept of 'idiopathic' Parkinson's disease (PD) as a single entity has been challenged with the identification of several clinical subtypes, pathogenic genes and putative causative environmental agents. In addition to classic motor symptoms, non-motor manifestations (such as rapid eye movement sleep disorder, anosmia, constipation and depression) appear at prodromic/premotor stage and evolve, along with cognitive impairment and dysautonomia, as the disease progresses, often dominating the advanced stages of the disease. The key molecular pathogenic mechanisms include α-synuclein misfolding and aggregation, mitochondrial dysfunction, impairment of protein clearance (associated with deficient ubiquitin-proteasome and autophagy-lysosomal systems), neuroinflammation and oxidative stress. The involvement of dopaminergic as well as noradrenergic, glutamatergic, serotonergic and adenosine pathways provide insights into the rich and variable clinical phenomenology associated with PD and the possibility of alternative therapeutic approaches beyond traditional dopamine replacement therapies.One of the biggest challenges in the development of potential neuroprotective therapies has been the lack of reliable and sensitive biomarkers of progression. Immunotherapies such as the use of vaccination or monoclonal antibodies directed against aggregated, toxic α-synuclein.as well as anti-aggregation or protein clearance strategies are currently investigated in clinical trials. The application of glucagon-like peptide one receptor agonists, specific PD gene target agents (such as GBA or LRRK2 modifiers) and other potential disease modifying drugs provide cautious optimism that more effective therapies are on the horizon. Emerging therapies, such as new symptomatic drugs, innovative drug delivery systems and novel surgical interventions give hope to patients with PD about their future outcomes and prognosis.