The levodopa wearing-off phenomenon in Parkinson’s disease: pharmacokinetic considerations

Opicapone to Treat Early Wearing-off in Parkinson's Disease Patients: The Korean ADOPTION Trial

BACKGROUND

Increasing levodopa (L-dopa)/dopa decarboxylase inhibitor (DDCI) daily dose or adding a catechol-O-methyltransferase (COMT) inhibitor to levodopa/DDCI therapy are strategies used to manage wearing-off symptoms in Parkinson's disease (PD) patients.

OBJECTIVES

To evaluate the COMT inhibitor opicapone versus an additional dose of levodopa to treat early wearing-off in PD patients.

METHODS

ADOPTION was a randomized, parallel-group, open-label, Phase 4 study conducted in Korea. At baseline, eligible patients were randomized (1:1) to opicapone 50 mg (n = 87) or L-dopa 100 mg (n = 81) (added to current L-dopa/DDCI therapy) for 4 weeks. The main efficacy endpoint was change from baseline to end of study in absolute off time. Other endpoints included changes in on time, in Movement Disorder Society-Unified Parkinson's Disease Rating Scale and 8-item PD Questionnaire scores, and the Clinical and Patient Global Impression of Improvement/Change.

RESULTS

The adjusted mean in absolute off time was significantly greater for opicapone 50 mg than for L-dopa 100 mg (-62.1 vs. -16.7 minutes; P = 0.0015). Opicapone-treated patients also reported a greater reduction in the percentage of off time (P = 0.0015), a greater increase in absolute on time (P = 0.0338) and a greater increase in the percentage of on time (P = 0.0015). There were no significant differences in other secondary endpoints. The L-dopa equivalent daily dose was significantly higher in the opicapone group (750.9 vs. 690.0 mg; P = 0.0247), when a 0.5 conversion factor is applied.

CONCLUSIONS

Opicapone 50 mg was more effective than an additional 100 mg L-dopa dose at decreasing off time in patients with PD and early wearing-off.

Dissolvable microarray patches of levodopa and carbidopa for Parkinson's disease management

Carbidopa and levodopa remain the established therapeutic standard for managing Parkinson's disease. Nevertheless, their oral administration is hindered by rapid enzymatic degradation and gastrointestinal issues, limiting their efficacy, and necessitating alternative delivery methods. This work presents a novel strategy employing dissolving microarray patches (MAPs) loaded with carbidopa and levodopa, formulated with Tween® 80 to improve their transdermal delivery. The fabricated MAPs demonstrated an acceptable mechanical strength, resisting pressures equivalent to manual human thumb application (32 N) onto the skin. Additionally, these MAPs exhibited an insertion depth of up to 650 µm into excised neonatal porcine skin. Ex vivo dermatokinetic studies could achieve delivery efficiencies of approximately 53.35 % for levodopa and 40.14 % for carbidopa over 24 h, demonstrating their significant potential in drug delivery. Biocompatibility assessments conducted on human dermal fibroblast cells corroborated acceptable cytocompatibility, confirming the suitability of these MAPs for dermal application. In conclusion, dissolving MAPs incorporating carbidopa and levodopa represent a promising alternative for improving the therapeutic management of Parkinson's disease.

Effectiveness of Continuous Dopaminergic Therapies in Parkinson's Disease: A Review of L-DOPA Pharmacokinetics/Pharmacodynamics

Background

Parkinson's disease (PD) is characterized by striatal dopamine deficiency. Since dopamine cannot cross the digestive and blood-brain barriers, its precursor, levodopa (L-DOPA), remains the mainstay of treatment. However, the significant pharmacokinetic (Pk) and pharmacodynamic (Pd) limitations of L-DOPA, combined with the severity of PD, may trigger motor and non-motor complications, for which continuous dopaminergic delivery therapies have been developed.

Objective

The aim of this study was to review the literature on the Pk/Pd limitations of L-DOPA and how current treatments of continuous dopaminergic administration ameliorate these problems, in order to identify the need for new therapeutic avenues.

Methods

A comprehensive literature search was carried out using PubMed and 75 articles were initially extracted. Following independent screening by two reviewers and consideration of eligibility, 10 articles were chosen for further analysis. Information concerning the Pk/Pd of L-DOPA was classified for each article.

Results

Pk/Pd problems notably include: (i) restricted digestive and cerebral absorption; (ii) unnecessary peripheral distribution; (iii) short half-life; (iv) age- and PD-induced decline of central aromatic L-amino acid decarboxylase; (v) misdistribution in many cells; and (vii) pulsatile stimulation of dopaminergic receptors. Current treatments only slightly ameliorate some of these problems.

Conclusions

Many Pk/Pd constraints are not resolved by existing continuous dopaminergic delivery therapies. This highlights the significant gap between these treatments and the ideal of continuous dopaminergic stimulation.

Structural underpinnings and long-term effects of resilience in Parkinson's disease

Resilience in neuroscience generally refers to an individual's capacity to counteract the adverse effects of a neuropathological condition. While resilience mechanisms in Alzheimer's disease are well-investigated, knowledge regarding its quantification, neurobiological underpinnings, network adaptations, and long-term effects in Parkinson's disease is limited. Our study involved 151 Parkinson's patients from the Parkinson's Progression Marker Initiative Database with available Magnetic Resonance Imaging, Dopamine Transporter Single-Photon Emission Computed Tomography scans, and clinical information. We used an improved prediction model linking neuropathology to symptom severity to estimate individual resilience levels. Higher resilience levels were associated with a more active lifestyle, increased grey matter volume in motor-associated regions, a distinct structural connectivity network and maintenance of relative motor functioning for up to a decade. Overall, the results indicate that relative maintenance of motor function in Parkinson's patients may be associated with greater neuronal substrate, allowing higher tolerance against neurodegenerative processes through dynamic network restructuring.

Safety and Efficacy of IPX203 in Parkinson's Disease: The RISE-PD Open-Label Extension Study

BACKGROUND

IPX203 is a novel oral extended-release formulation of carbidopa/levodopa (CD/LD) developed to address the short half-life of immediate-release CD/LD. In the phase 3 RISE-PD trial, IPX203 significantly improved "Good On" time in patients with Parkinson's disease compared with immediate-release CD/LD.

OBJECTIVES

To evaluate the safety and efficacy of IPX203 in an open-label extension of the pivotal phase 3 study.

METHODS

This 9-month extension enrolled patients who completed the randomized, double-blind trial. Key efficacy endpoints included Movement Disorder Society-Unified Parkinson's Disease Rating Scale and Patient and Clinical Global Impression scores. Adverse events (AEs) were recorded.

RESULTS

Improvements in efficacy were maintained and dosing frequency and total daily dose remained stable through the trial. A total of 52.7% of patients experienced ≥1 treatment-emergent AE, mostly mild or moderate and occurred within the first 90 days of treatment.

CONCLUSIONS

In this phase 3 open-label extension, IPX203 exhibited a favorable safety and tolerability profile and sustained efficacy of comparable magnitude to the end of the double-blind study. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Convergent and divergent intra- and internetwork connectivity in Parkinson's disease with wearing-off

OBJECTIVE

Our study aimed to explore the functional connectivity alterations between cortical nodes of resting-state networks in Parkinson's disease (PD) patients with wearing-off (WO) at different levels.

METHODS

Resting-state functional magnetic resonance imaging was performed on 36 PD patients without wearing-off (PD-nWO), 30 PD patients with wearing-off (PD-WO), and 35 healthy controls (HCs) to extract functional networks. Integrity, network, and edge levels were calculated for comparison between groups. UPDRS-III, MMSE, MOCA, HAMA, and HAMD scores were collected for further regression analysis.

RESULTS

We observed significantly reduced connectivity strength in the dorsal attention network and limbic network in the PD-WO group compared with the HC group. The PD-WO group showed a decreased degree of functional connectivity at 12 nodes, including the bilateral orbital part of the superior frontal gyrus, right olfactory cortex, left medial orbital part of the superior frontal gyrus, bilateral gyrus rectus, right parahippocampal gyrus, right thalamus, left Heschl's gyrus, right superior temporal gyrus part of the temporal pole, left middle temporal gyrus part of the temporal pole, and right inferior temporal gyrus. Furthermore, the PD-WO group showed a significantly lower degree of functional connectivity in the left orbital part of the superior frontal gyrus and right gyrus rectus than the PD-nWO group. Internetwork analysis indicated reduced functional connectivity in five pairs of resting-state networks.

CONCLUSION

Our results demonstrated altered intra- and internetwork connections in PD patients with WO. These findings will facilitate a better understanding of the distinction between the network changes in PD pathophysiology.

Rationale and Development of Tavapadon, a D1/D5-Selective Partial Dopamine Agonist for the Treatment of Parkinson's Disease

Currently, available therapeutics for the treatment of Parkinson's disease (PD) fail to provide sustained and predictable relief from motor symptoms without significant risk of adverse events (AEs). While dopaminergic agents, particularly levodopa, may initially provide strong motor control, this efficacy can vary with disease progression. Patients may suffer from motor fluctuations, including sudden and unpredictable drop-offs in efficacy. Dopamine agonists (DAs) are often prescribed during early-stage PD with the expectation they will delay the development of levodopa-associated complications, but currently available DAs are less effective than levodopa for the treatment of motor symptoms. Furthermore, both levodopa and DAs are associated with a significant risk of AEs, many of which can be linked to strong, repeated stimulation of D2/D3 dopamine receptors. Targeting D1/D5 dopamine receptors has been hypothesized to produce strong motor benefits with a reduced risk of D2/D3-related AEs, but the development of D1-selective agonists has been previously hindered by intolerable cardiovascular AEs and poor pharmacokinetic properties. There is therefore an unmet need in PD treatment for therapeutics that provide sustained and predictable efficacy, with strong relief from motor symptoms and reduced risk of AEs. Partial agonism at D1/D5 has shown promise for providing relief from motor symptoms, potentially without the AEs associated with D2/D3-selective DAs and full D1/D5-selective DAs. Tavapadon is a novel oral partial agonist that is highly selective at D1/D5 receptors and could meet these criteria. This review summarizes currently available evidence of tavapadon's therapeutic potential for the treatment of early through advanced PD.

Should continuous dopaminergic stimulation be a standard of care in advanced Parkinson's disease?

The standard of care is a term that refers to the level of care, skill, and treatment that a healthcare provider should offer to a patient based on the current scientific evidence and the level of medical knowledge available in the field. For Parkinson's disease (PD), the standard care is mostly considered to be oral treatment with dopaminergic drugs, particularly levodopa which remains the 'gold standard'. However, effective management with levodopa during the later stages of the disease becomes increasingly challenging due to the ongoing neurodegenerative process, the consequences of its pulsatile dopaminergic stimulation, and the gastrointestinal barriers to effective drug absorption. As a result, the concept of applying continuous dopaminergic stimulation has emerged with infusion therapies (continuous subcutaneous apomorphine, levodopa-carbidopa intestinal gel, and levodopa-entacapone-carbidopa intestinal gel infusion). These therapies seek to provide continuous stimulation of striatal dopamine receptors that is efficient not only in alleviating clinical symptoms, but also in delaying, reducing, and possibly preventing the onset of levodopa-related motor (fluctuations, dyskinesia) and non-motor complications; and they are also associated with clinically relevant side effects. Clinical studies and real-life experience support the notion that infusion therapies should be accepted as part of the standard of care for patients with advanced PD who have refractory, severe, and disabling motor complications that affect their quality of life. However, they should be considered based on the needs of individualized patients and the access to these advanced therapies needs to be made more accessible to the general PD population.

No Increase in Symptoms Toward the End of the Ocrelizumab Infusion Cycle in Patients With Multiple Sclerosis: Symptom Burden on Ocrelizumab: A Longitudinal Study (SymBOLS)

Background and Objectives

Some patients with multiple sclerosis (MS) receiving ocrelizumab (OCR) report worsening symptoms toward the end of the 6-month infusion cycle ('wearing off'). The objective of our study was to comprehensively assess changes in symptom burden across 2 consecutive OCR infusion cycles.

Methods

SYMptom Burden on Ocrelizumab, a Longitudinal Study (SymBOLS; NCT04855617) was an investigator-initiated, 2-center study of patients with MS starting or receiving OCR. Patients' symptoms were assessed with NeuroQoL short forms, SymptoMScreen, and Work Productivity and Activity Impairment Questionnaire at the start-cycle, mid-cycle, and end-cycle time points in each of the 2 infusion cycles. Symptom scores at the 3 time points within each cycle were compared with repeated-measures ANOVA or the Friedman rank-sum test for non-normal variables. The proportions of patients with a meaningful symptomatic change from the start to the end of each infusion cycle were calculated, and patients whose symptoms improved, worsened, and stayed the same from the start to the end of the cycle were compared with respect to demographic and clinical characteristics.

Results

One hundred three patients with MS provided longitudinal data for analyses (mean age [SD]: 46.7 [12.2] years, 68% female, 33% non-White, disease duration: 15.5 [5] years, 41% with the Extended Disability Status Scale score >3). On a group level, NeuroQoL and SymptoMScreen scores mostly remained stable or even improved slightly toward the end of each cycle. On an individual level, symptoms remained unchanged across either cycle for most patients, and meaningful symptom worsening from the start to the end of the cycle was no more common than improvement. Meaningful change in symptoms in both cycles was very rare and generally in the direction of improvement toward the end cycle. Despite the lack of evidence for symptom worsening with a longer time from infusion, 54% of patients endorsed feeling of "wearing off" at least sometimes, most commonly as an increase in fatigue.

Discussion

Our prospective study failed to uncover evidence for the worsening of symptoms with a longer time from OCR infusion. These findings cast doubt on the existence of wearing off as a physiologic phenomenon in OCR-treated patients with MS. The perception of wearing off is likely the result of natural fluctuations in MS symptoms and attribution bias.

Model-based optimization of controlled release formulation of levodopa for Parkinson's disease

Levodopa is currently the standard of care treatment for Parkinson's disease, but chronic therapy has been linked to motor complications. Designing a controlled release formulation (CRF) that maintains sustained and constant blood concentrations may reduce these complications. Still, it is challenging due to levodopa's pharmacokinetic properties and the notion that it is absorbed only in the upper small intestine (i.e., exhibits an "absorption window"). We created and validated a physiologically based mathematical model to aid the development of such a formulation. Analysis of experimental results using the model revealed that levodopa is well absorbed throughout the entire small intestine (i.e., no "absorption window") and that levodopa in the stomach causes fluctuations during the first 3 h after administration. Based on these insights, we developed guidelines for an improved CRF for various stages of Parkinson's disease. Such a formulation is expected to produce steady concentrations and prolong therapeutic duration compared to a common CRF with a smaller dose per day and a lower overall dose of levodopa, thereby improving patient compliance with the dosage regime.

Clinical Use of On-Demand Therapies for Patients with Parkinson's Disease and OFF Periods

On-demand therapies for Parkinson's disease (PD) provide rapid, reliable relief for patients experiencing OFF periods; however, practical guidelines on the use of these therapies are not generally available. This paper reviews the use of on-demand treatments. Motor fluctuations occur in nearly all patients with PD after long-term use of levodopa. As the goal of PD treatment is to provide good ON time, on-demand treatments that have a more rapid reliable onset than the slower-acting oral medications provide rapid relief for OFF periods. All current on-demand treatments bypass the gastrointestinal tract, providing dopaminergic therapy directly into the blood stream by subcutaneous injection, through the buccal mucosa, or by inhalation into the pulmonary circulation. On-demand treatments are fast acting (10- to 20-min onset), with maximum, reliable, and significant responses reached within 30 min after administration. Oral medications pass through the gastrointestinal tract and thus have slower absorption owing to gastroparesis and competition with food. On-demand therapies, by providing fast-acting relief, can have a positive impact on a patient's quality of life when patients are experiencing OFF periods.

Monitoring medication optimization in patients with Parkinson's disease

Medication optimization is a common component of the treatment strategy in patients with Parkinson's disease. As the disease progresses, it is essential to compensate for the movement deterioration in patients. Conventionally, examining motor deterioration and prescribing medication requires the patient's onsite presence in hospitals or practices. Home-monitoring technologies can remotely deliver essential information to physicians and help them devise a treatment decision according to the patient's need. Additionally, they help to observe the patient's response to these changes. In this regard, we conducted a longitudinal study to collect gait data of patients with Parkinson's disease while they received medication changes. Using logistic regression classifier, we could detect the annotated motor deterioration during medication optimization with an accuracy of 92%. Moreover, an in-depth examination of the best features illustrated a decline in gait speed and swing phase duration in the deterioration phases due to suboptimal medication.Clinical relevance- Our proposed gait analysis method in this study provides objective, detailed, and punctual information to physicians. Revealing clinically relevant time points related to the patient's need for medical adaption alleviates therapy optimization for physicians and reduces the duration of suboptimal treatment for patients. As the home-monitoring system acts remotely, embedding it in the medical care pathways could improve patients' quality of life.

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.

Optimizing levodopa therapy, when and how? Perspectives on the importance of delivery and the potential for an early combination approach

INTRODUCTION

There is currently a resurgence of levodopa as the initial treatment of choice for most patients with Parkinson's disease, albeit at lower doses than previously used. The addition of adjuvant treatments (including MAO-B inhibitors, COMT inhibitors and dopamine agonists) is an established strategy to reduce motor complications that develop with sustained levodopa therapy.

AREAS COVERED

In this narrative review, the authors discuss the evidence underpinning current levodopa optimization strategies, during early disease and once motor complications occur. To support the discussion, the authors performed a broad PubMed search with the terms 'levodopa/L-dopa/L-Dopa, and Parkinson's disease,' restricted to clinical trials. There is now a wealth of evidence that improving levodopa delivery to the brain improves outcomes and we discuss how agents can be combined earlier in the course of disease to leverage the full potential of this strategy.

EXPERT OPINION

Levodopa remains the cornerstone of antiparkinsonian therapy. Several promising advances in formulation have been made and include novel extended-release oral drugs as well as non-oral delivery systems. However, evidence has long suggested that anti-parkinsonian medications may be better used in combination earlier in the disease, and consequently patients will benefit from low doses of several agents rather than ever larger levodopa doses.

Tailoring Motor Fluctuation Treatment: Beyond Levodopa Dose Adjustment

Susan Fox opened this satellite symposium at the 8th European Academy of Neurology (EAN) Congress with an overview of the concept of motor fluctuations (MF) in Parkinson’s disease (PD). She emphasised that levodopa remains the gold standard therapy for PD. However, MFs are one of the critical complications of levodopa therapy that affect many patients with advancing PD and, when diagnosed, represent a challenge in patient management. Alternative options are, therefore, needed to provide continuous dopaminergic stimulation while maximising the levodopa benefit. Despite different options, Angelo Antonini showed that neurologists often prefer to adjust levodopa dose rather than add an adjunctive agent. Market research confirms that, in patients with PD, the levodopa dose is adjusted in around 80% of patients, while only 20% have adjunct therapy as a first-line option. Adjusting the levodopa dose, either by increasing or fractionating the dose, or both, remains a valid, tried-and-tested option, although it has limitations. Joaquim Ferreira presented emerging evidence from a Phase II clinical trial, suggesting a potential benefit of adding opicapone 50 mg compared with 100 mg levodopa to treat patients with PD and end-of-dose fluctuations. This symposium aimed to present the effect of opicapone with relatively low total daily doses of levodopa; an option that may not have been traditionally considered by neurologists who are used to adjusting levodopa as a first-line response.

Effect of Opicapone on Levodopa Pharmacokinetics in Patients with Fluctuating Parkinson's Disease

BACKGROUND

Inhibiting catechol-O-methyltransferase extends the plasma half-life of levodopa, potentially allowing physicians to optimize the levodopa regimen in patients with Parkinson's disease (PD) experiencing motor fluctuations.

OBJECTIVES

To evaluate the effects of once-daily opicapone on levodopa plasma pharmacokinetics and motor response when added to two different levodopa dosing regimens.

METHODS

A total of 24 patients with PD and motor fluctuations were enrolled in an exploratory, open-label, modified cross-over trial. Participants first received levodopa/carbidopa 500/125 mg (five intakes) for 2 weeks and were then randomly assigned (1:1) to levodopa/carbidopa 400/100 mg given over either four or five daily intakes plus opicapone 50 mg for an additional 2 weeks. Levodopa 12-hour pharmacokinetics was the primary outcome (ie, excluding the effect of last/evening levodopa/carbidopa intake), with motor complications evaluated as secondary outcomes.

RESULTS

Over 12-hour pharmacokinetics and compared with five-intake levodopa/carbidopa 500/125 mg without opicapone, maximal levodopa concentrations were similar or nonsignificantly higher on both levodopa/carbidopa 400/100 mg regimens plus opicapone. Despite a 100 mg lower total levodopa/carbidopa daily dose, adding opicapone 50 mg at least doubled the levodopa plasma half-life and minimal concentrations, with a significant ≈30% increase in total exposure. The levodopa fluctuation index was only significantly lower for the five intakes plus opicapone regimen (difference of -71.8%; P < 0.0001). Modifications to levodopa pharmacokinetics were associated with decreased off time and increased on time.

CONCLUSIONS

Combining opicapone 50 mg with a 100 mg lower daily dose of levodopa provides higher levodopa bioavailability with avoidance of trough levels. Despite the lower levodopa dose, modifying the levodopa pharmacokinetic profile with opicapone was associated with decreased off time and increased on time. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Patient-specific in vitro drug release testing coupled with in silico PBPK modeling to forecast the in vivo performance of oral extended-release levodopa formulations in Parkinson's disease patients

Biorelevant in vitro release models are valuable analytical tools for oral drug development but often tailored to gastrointestinal conditions in 'average' healthy adults. However, predicting in vivo performance in individual patients whose gastrointestinal conditions do not match those of healthy adults would be of great value for optimizing oral drug therapy for such patients. This study focused on establishing patient-specific in vitro and in silico models to predict the in vivo performance of levodopa extended-release products in Parkinsońs disease patients. Current knowledge on gastrointestinal conditions in these patients was incorporated into model development. Relevant in vivo pharmacokinetic data and patient-specific in vitro release data from a novel in vitro test setup were integrated into patient-specific physiologically-based pharmacokinetic models. AUC, c_max and t_max of the computed plasma profiles were calculated using PK-Sim®. For the products studied, levodopa plasma concentration-time profiles modeled using this novel approach compared far better with published average plasma profiles in Parkinsońs disease patients than those derived from in vitro release data obtained from the 'average' healthy adult setup. Although further work is needed, results of this study highlight the importance of addressing patient-specific gastrointestinal conditions when aiming to predict drug release in such specific patient groups.

Opicapone, a Novel Catechol-O-methyl Transferase Inhibitor, for Treatment of Parkinson's Disease "Off" Episodes

Parkinson's Disease (PD) is a common neurodegenerative disorder and the leading cause of disability. It causes significant morbidity and disability through a plethora of symptoms, including movement disorders, sleep disturbances, and cognitive and psychiatric symptoms. The traditional pathogenesis theory of PD involves the loss of dopaminergic neurons in the substantia nigra (SN). Classically, treatment is pursued with an assortment of medications that are directed at overcoming this deficiency with levodopa being central to most treatment plans. Patients taking levodopa tend to experience "off episodes" with decreasing medication levels, causing large fluctuations in their symptoms. These off episodes are disturbing and a source of morbidity for these patients. Opicapone is a novel, peripherally acting Catechol-O-methyl transferase (COMT) inhibitor that is used as adjunctive therapy to carbidopa/levodopa for treatment and prevention of "off episodes." It has been approved for use as an adjunct to levodopa since 2016 in Europe and has recently (April 2020) gained FDA approval for use in the USA. By inhibiting COMT, opicapone slows levodopa metabolism and increases its availability. Several clinical studies demonstrated significant improvement in treatment efficacy and reduction in duration of "off episodes." The main side effect demonstrated was dyskinesia, mostly with the 100mg dose, which is higher than the approved, effective dose of 50mg. Post-marketing surveillance and analysis are required to further elucidate its safety profile and contribute to patient selection. This paper reviews the seminal and latest evidence in the treatment of PD "off episodes" with the novel drug Opicapone, including efficacy, safety, and clinical indications.

Istradefylline for OFF Episodes in Parkinson’s Disease: A US Perspective of Common Clinical Scenarios

The effective management of OFF episodes remains an important unmet need for patients with Parkinson’s disease (PD) who develop motor complications with long-term levodopa therapy. Istradefylline is a selective adenosine A_2A receptor antagonist for the treatment of patients with PD experiencing OFF episodes while on levodopa/decarboxylase inhibitor. Originally approved in Japan, istradefylline was recently approved in the USA. In this article, we provide a specific review of the four clinical studies that the FDA included in the approval of istradefylline in the USA, and discuss common clinical scenarios, based on our experience, where treatment with istradefylline may benefit patients experiencing motor fluctuations.

Intranasal Nanoemulsions A Potential Strategy for Targeting The Neurodegenerative Disorder: Parkinson's

Intranasal delivery has great potential to cross the blood-brain barrier and deliver the drug molecule into the central nervous system faster than traditional methods. The olfactory neuronal and trigeminal pathways both are involved in intranasal delivery. The nano-technology is an innovative strategy for the nose to brain delivery. The mucoadhesive nanoemulsion formulation is a modified technology that increases the duration of drug accumulation and provides prolonged delivery at a targeted site. The nanoemulsion formulation oil, surfactant, and co-surfactant components maintain lower surface tension and particle coalescence. The globule dimension and zeta potential are affected in brain targeting. The globule size of the innovative formulation should be < 200 nm for drug permeation because, in humans, the average axon magnitude ranges from around 100 to 700. Furthermore, modified technology of nanoemulsion like nanogel and nanoemulsion in-situ gel provide a great advantage to cure neurodegenerative disorders. Therefore, focusing on the innovative pharmaceutical approaches of nanoemulsion in intranasal drug delivery, the current review provides insight into the applications of nanoemulsion in neurodegenerative disorders like Parkinson's disease, which are due to the depletion of dopamine in substania nigra resulting in cardinal motor activity bradykinesia and tremors. The review also touches upon the pathways for intranasal delivery of nanoemulsion, the pathogenesis of Parkinson's disease, and the future direction of the research on intranasal nanoemulsion.

Simultaneous Measurement of Striatal Dopamine and Hydrogen Peroxide Transients Associated with L-DOPA Induced Rotation in Hemiparkinsonian Rats

Parkinson's disease (PD) is a neurodegenerative disorder commonly treated with levodopa (L-DOPA), which eventually induces abnormal involuntary movements (AIMs). The neurochemical contributors to these dyskinesias are unknown; however, several lines of evidence indicate an interplay of dopamine (DA) and oxidative stress. Here, DA and hydrogen peroxide (H2O2) were simultaneously monitored at discrete recording sites in the dorsal striata of hemiparkinsonian rats using fast-scan cyclic voltammetry. Mass spectrometry imaging validated the lesions. Hemiparkinsonian rats exhibited classic L-DOPA-induced AIMs and rotations as well as increased DA and H2O2 tone over saline controls after 1 week of treatment. By week 3, DA tone remained elevated beyond that of controls, but H2O2 tone was largely normalized. At this time point, rapid chemical transients were time-locked with spontaneous bouts of rotation. Striatal H2O2 rapidly increased with the initiation of contraversive rotational behaviors in lesioned L-DOPA animals, in both hemispheres. DA signals simultaneously decreased with rotation onset. The results support a role for these striatal neuromodulators in the adaptive changes that occur with L-DOPA treatment in PD and reveal a precise interplay between DA and H2O2 in the initiation of involuntary locomotion.

Efficacy and safety of istradefylline in patients with Parkinson's disease presenting with postural abnormalities: Results from a multicenter, prospective, and open-label exploratory study in Japan

Postural abnormalities in Parkinson's disease (PD) can devastatingly impair the quality of life, especially in patients with advanced disease, and are generally refractory to dopaminergic agents. The objective of this exploratory study was to investigate the efficacy and safety of istradefylline for the treatment of postural abnormalities in PD. In this open-label, 24-week, single-arm prospective trial, PD patients with postural abnormalities experiencing the wearing-off phenomenon on levodopa-containing therapies were enrolled and received a starting dose of 20 mg/day istradefylline orally for 4 weeks, which was then increased to 40 mg/day. The primary endpoint was the change from baseline to week 24 in the 14-item Unified Dystonia Rating Scale (UDRS) total score. Pivotal secondary endpoints were changes in the sub-items of UDRS, Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III, and adverse drug reactions (ADRs). Overall, 24/31 enrolled patients completed the study; mean (standard deviation) age and duration of motor complications were 73.3 (7.7) years and 3.2 (4.4) years, respectively. Mean (95% confidence interval [CI]) change in the UDRS total score was 4.84 (1.97, 7.71; P = 0.002), with significant improvements in the neck, right distal arm and hand, and trunk severity scores. Mean (95% CI) change in the MDS-UPDRS part III score was 7.84 (4.34, 11.34; P < 0.001). The most common ADRs were malaise, dyskinesia exacerbation, and visual hallucinations in 2 (6.5%) patients each. This exploratory study demonstrated that istradefylline could be efficacious for postural abnormalities and was generally well tolerated in patients with PD experiencing the wearing-off phenomenon with levodopa-containing therapies.

Deep Brain Stimulation and Treatment Outcomes of Young- and Late-Onset (≤55 Years) Parkinson's Disease: A Population-Based Study

Background: No studies have reported the rate of motor complications (MC) and response to medical and surgical treatment in a population-based cohort of young-onset Parkinson's Disease (YOPD) patients and a cohort of sex-matched late-onset Parkinson's Disease (LOPD).

Objective: To assess the outcomes of dopaminergic treatment in YOPD and LOPD, explore treatment-induced MC, medical adjustment, and rate of deep brain stimulation (DBS).

Methods: We used the expanded Rochester Epidemiology Project (eREP) to investigate a population-based cohort of YOPD between 2010 and 2015 in 7 counties in Minnesota. Cases with onset ≤55 years of age were included as YOPD. An additional sex-matched cohort of LOPD (onset at ≥56 years of age) was included for comparison. All medical records were reviewed to confirm the diagnoses.

Results: In the seven counties 2010–15, there were 28 YOPD patients, which were matched with a LOPD cohort. Sixteen (57%) YOPD had MC, as compared to 9 (32%) LOPD. In YOPD, 9 had motor fluctuations (MF) and Levodopa-induced dyskinesia (LID) together, whereas 3 had LID only and 4 MF only. In LOPD, 3 had MF and LID, 3 MF only, and 3 LID only. Following medical treatment for MC, 6/16 YOPD (38%) and 3/9 (33%) LOPD had symptoms resolution. In YOPD, 11/16 (69%) were considered for DBS implantation, in LOPD they were 2/9 (22%), but only 7 (6 YOPD and 1 LOPD) underwent the procedure. YOPD had significantly higher rates in both DBS candidacy and DBS surgery (respectively, p = 0.03 and p = 0.04). Among DBS-YOPD, 5/6 (83%) had positive motor response to the surgery; the LOPD case had a poor response. We report the population-based incidence of both YOPD with motor complications and YOPD undergoing DBS, which were 1.17 and 0.44 cases per 100,000 person-years, respectively.

Conclusion: Fifty-seven percent of our YOPD patients and 32% of the LOPD had motor complications. Roughly half of both YOPD and LOPD were treatment resistant. YOPD had higher rates of DBS candidacy and surgery. Six YOPD and 1 LOPD underwent DBS implantation and most of them had a positive motor response after the surgery.

Opicapone for the Treatment of Parkinson's Disease "Off" Episodes: Pharmacology and Clinical Considerations

Parkinson's disease (PD) is a common neurodegenerative disorder. It is also the fastest-growing neurodegenerative disorder and has more than doubled between 1990 and 2016. Parkinson's disease causes significant morbidity and disability from motor dysfunction, sleep disturbances, and cognitive and psychiatric symptoms. This paper reviews recent evidence in the treatment of PD "off" episodes with the novel drug opicapone, including its efficacy, safety, and clinical indications. Opicapone is a novel, peripherally acting catechol-O-methyl transferase (COMT) inhibitor used as adjunctive therapy to carbidopa/levodopa for treatment and prevention of "off" episodes. It has been approved for use as an adjunct to levodopa since 2016 in Europe and has recently (April 2020) gained FDA approval for use in the USA. By inhibiting COMT, opicapone slows levodopa metabolism and increases its availability. Several clinical studies demonstrated significant improvement in treatment efficacy and reduction in the duration of "off" episodes The main side effect demonstrated was dyskinesia, mostly with the 100 mg dose, which is higher than the approved, effective dose of 50 mg.

Redefining the strategy for the use of COMT inhibitors in Parkinson's disease: the role of opicapone

INTRODUCTION

Levodopa remains the gold-standard Parkinson's disease (PD) treatment, but the inevitable development of motor complications has led to intense activity in pursuit of its optimal delivery.

AREAS COVERED

Peripheral inhibition of dopa-decarboxylase has long been considered an essential component of levodopa treatment at every stage of illness. In contrast, only relatively recently have catechol-O-methyltransferase (COMT) inhibitors been utilized to block the other major pathway of degradation and optimize levodopa delivery to the brain. First and second-generation COMT inhibitors were deficient because of toxicity, sub-optimal pharmacokinetics or a short duration of effect. As such, they have only been employed once 'wearing-off' has developed. However, the third-generation COMT inhibitor, opicapone has overcome these difficulties and exhibits long-lasting enzyme inhibition without the toxicity observed with previous generations of COMT inhibitors. In clinical trials and real-world PD studies opicapone improves the levodopa plasma profile and results in a significant improvement in ON time in 'fluctuating' disease, but it has not yet been included in the algorithm for early treatment.

EXPERT OPINION

This review argues for a shift in the positioning of COMT inhibition with opicapone in the PD algorithm and lays out a pathway for proving its effectiveness in early disease.

Opicapone for Parkinson's disease: clinical evidence and future perspectives

Since 2016, opicapone (OPC), a potent third-generation, long-acting, once-daily, peripheral catechol-O-methyltransferase inhibitor, is approved as an add-on to levodopa in Parkinson's disease patients with motor fluctuations. OPC 50 mg has showed to be able in reducing OFF time by an average of about 60 min daily compared with placebo, to further reduce OFF-time of about 39 min, when switched from ENT to OPC and to be safe. These beneficial effects of OPC were maintained for 1 year. Recently, several post hoc analysis and few pilot observational open-label studies, have suggested its efficacy and wider applicability for different phenotypes of motor complications and for Parkinson's disease stages. Here we review OPC applicability and perspectives, in the light of the more recently published analysis.

Nusinersen Wearing-Off in Adult 5q-Spinal Muscular Atrophy Patients

The antisense oligonucleotide nusinersen was the first drug treatment available for all types of 5q-spinal muscular atrophy (SMA). The dosing regime has been derived from pivotal clinical trials in infants and children. The efficacy of nusinersen in severely affected adult SMA patients is still questionable, as no placebo-controlled trials have been conducted. In the present study, we systematically examined wearing-off phenomena during nusinersen maintenance dosing using a patient-centered approach. We found that adult SMA patients perceived wearing-off after nearly half of 51 investigated nusinersen administrations, primarily within the last month prior to the next administration. Symptoms and functions affected were mainly general strength and arm and leg muscle function next to endurance and independence in daily routine. Lack of walking ability and higher body mass index were characteristic phenotypic features in patients with consistent wearing-off effects. We assume that specific SMA phenotypes might benefit from higher dosing, shorter treatment intervals, change of treatment administration or a combination of all. Efforts towards treatment optimization may result in higher efficacy in distinct phenotypes.

Update on the Management of Parkinson's Disease for General Neurologists

Management of Parkinson's disease (PD) is complicated due to its progressive nature, the individual patient heterogeneity, and the wide range of signs, symptoms, and daily activities that are increasingly affected over its course. The last 10–15 years have seen great progress in the identification, evaluation, and management of PD, particularly in the advanced stages. Highly specialized information can be found in the scientific literature, but updates do not always reach general neurologists in a practical and useful way, potentially creating gaps in knowledge of PD between them and neurologists subspecialized in movement disorders, resulting in several unmet patient needs. However, general neurologists remain instrumental in diagnosis and routine management of PD. This review provides updated practical information to identify problems and resolve common issues, particularly when the advanced stage is suspected. Some tips are provided for efficient communication with the members of a healthcare team specialized in movement disorders, in order to find support at any stage of the disease in a given patient, and especially for a well-timed decision on referral.

From OFF to ON—Treating OFF Episodes in Parkinson’s Disease

In Parkinson’s disease (PD), OFF episodes continue to present a serious burden for patients, and their effective management remains a substantial unmet clinical need. Understanding of the pathophysiology of OFF episodes has advanced in recent years, providing valuable insights for improved treatments. OFF episodes generally appear 3–5 years after starting levodopa treatment, but can begin much earlier. They are characterized by motor symptoms (including tremor, rigidity, slowness, incoordination, and weakness) and are almost always associated with some non-motor symptoms (including psychological symptoms, pain, urinary problems, swallowing difficulties, and shortness of breath). In PD, higher doses of levodopa are associated with increased risk of motor and non-motor complications, which are notable limitations for longterm therapy. Their occurrence is associated with intermittent levodopa delivery and consequent fluctuating plasma levels. These issues can be offset using lower levodopa doses where possible, incremental dose increases, and combinations of levodopa with other pharmacological agents. OFF episodes in PD can be caused by gastroparesis and/or by Helicobacter pylori infection, which delays delivery of levodopa. These issues can be addressed using new formulations for continuous intrajejunal administration. In addition, pen injector, intranasal, and inhaled dosing systems have been studied and may provide relief via non-intestinal routes. Other approaches include deep-brain stimulation, which is effective but is restricted by costs and potential adverse events. This report presents the highlights of a satellite symposium held at the 14th International Conference on Alzheimer’s & Parkinson’s Diseases (AD/PD™ 2019), Lisbon, Portugal, which discussed the nature of OFF episodes in PD, associated risk factors and the potential of current and future treatments to effectively manage them and increase ON time.

Comparison of elderly and young patient populations treated with deep brain stimulation for Parkinson's disease: long-term outcomes with up to 7 years of follow-up

OBJECTIVE

Deep brain stimulation (DBS) is the procedure of choice for Parkinson's disease (PD). It has been used in PD patients younger than 70 years because of better perceived intra- and postoperative outcomes than in patients 70 years or older. However, previous studies with limited follow-up have demonstrated benefits associated with the treatment of elderly patients. This study aims to evaluate the long-term outcomes in elderly PD patients treated with DBS in comparison with a younger population.

METHODS

PD patients treated with DBS at the authors' institution from 2008 to 2014 were divided into 2 groups: 1) elderly patients, defined as having an age at surgery ≥ 70 years, and 2) young patients, defined as those < 70 years at surgery. Functional and medical treatment outcomes were evaluated using the Unified Parkinson's Disease Rating Scale part III (UPDRS III), levodopa-equivalent daily dose (LEDD), number of daily doses, and number of anti-PD medications. Study outcomes were compared using univariate analyses, 1-sample paired t-tests, and 2-sample t-tests.

RESULTS

A total of 151 patients were studied, of whom 24.5% were ≥ 70 years. The most common preoperative Hoehn and Yahr stages for both groups were 2 and 3. On average, elderly patients had more comorbidities at the time of surgery than their younger counterparts (1 vs 0, p = 0.0001) as well as a higher average LEDD (891 mg vs 665 mg, p = 0.008). Both groups experienced significant decreases in LEDD following surgery (elderly 331.38 mg, p = 0.0001; and young 108.6 mg, p = 0.0439), with a more significant decrease seen in elderly patients (young 108.6 mg vs elderly 331.38 mg, p = 0.0153). Elderly patients also experienced more significant reductions in daily doses (young 0.65 vs elderly 3.567, p = 0.0344). Both groups experienced significant improvements in motor function determined by reductions in UPDRS III scores (elderly 16.29 vs young 12.85, p < 0.0001); however, reductions in motor score between groups were not significant. Improvement in motor function was present for a mean follow-up of 3.383 years postsurgery for the young group and 3.51 years for the elderly group. The average follow-up was 40.6 months in the young group and 42.2 months in the elderly group.

CONCLUSIONS

This study found long-term improvements in motor function and medication requirements in both elderly and young PD patients treated with DBS. These outcomes suggest that DBS can be successfully used in PD patients ≥ 70 years. Further studies will expand on these findings.

Clinical and pharmacokinetics equivalence of multiple doses of levodopa benserazide generic formulation vs the originator (Madopar)

AIMS

While several generic preparations of levodopa/carbidopa and levodopa/benserazide (LBD) are currently available, pharmacokinetic (PK) equivalence and therapeutic equivalence studies with levodopa generics are not available in Italy. Lack of data on generic formulations is a critical factor for their limited use in this country and often lead patients to refuse the generic version of the branded drug.

METHODS

An experimental, 2-centre, randomized, double-blind, 2-sequence, noninferiority cross-over study was designed to evaluate both the PK equivalence and clinical equivalence of multiple doses of the generic preparation of LDB, Teva Italia, compared to the originator (Madopar). Forty-three out-patients with a diagnosis of idiopathic Parkinson's disease on LDB, were recruited and randomly assigned to 1 of 2 study sequences: generic-originator or originator-generic. Clinical evaluations were performed at the end of each study period. A PK study with an LDB fixed dose (100 + 25 mg) was performed in a subpopulation of 14 subjects.

RESULTS

Clinical data showed a reduction of 0.49 and 1.54 in the mean UPDRS III scores for the LDB and the originator, respectively. The 95% CIs [-2.21: 0.11] of the mean difference original vs LDB are smaller than the clinically significant difference of 3 UPDRS III points, supporting the conclusion that the treatment with LDB is not inferior to the originator. No statistically significant differences were found with respect to area under the curve to last dose, half-life, maximum concentration, time to maximum concentration and last observed concentration.

CONCLUSION

These findings prove the therapeutic clinical equivalence as well the PK equivalence of the generic LDB and the originator (Madopar).

Motor and non-motor wearing-off and its impact in the quality of life of patients with Parkinson's disease

OBJECTIVES

The wearing-off phenomenon is common in patients with Parkinson's disease. Motor and non-motor symptoms can fluctuate in relation to the "on/off" periods. To assess the impact of motor and non-motor wearing-off on activities of daily living and quality of life of patients with PD.

METHODS

A cross-sectional study was carried out. All patients were evaluated using the Movement Disorders Society Unified Parkinson's Disease Rating Scale. Wearing-off was assessed using the Wearing-Off Questionnaire-19, and quality of life was assessed using the Parkinson's Disease Questionnaire-8.

RESULTS

A total of 271 patients were included; 73.4% had wearing-off; 46.8% had both motor and non-motor fluctuations. Patients with both motor and non-motor wearing-off had a worst quality of life compared with those with only motor fluctuations (p = 0.047).

CONCLUSIONS

Motor and non-motor fluctuations have an impact on activities of daily living and quality of life. Non-motor wearing-off may have a higher impact.

Long-term outcomes of deep brain stimulation in severe Parkinson's disease utilizing UPDRS III and modified Hoehn and Yahr as a severity scale

OBJECTIVES

Deep brain stimulation (DBS) is the surgical treatment of choice for moderate to severe Parkinson's Disease (PD). However, few studies have assessed its efficacy in severe PD as defined by the modified Hoehn and Yahr scale (HY). This study evaluates long-term and medication outcomes of DBS in severe PD.

PATIENTS AND METHODS

We retrospectively collected the data of 15 patients from 2008 to 2014 with severe PD treated with DBS. Retrospective assessment with the modified Hoehn and Yahr scale and motor subset of the Unified Parkinson's Disease Rating Scale (UPDRS III) were used to objectively track severity and motor function improvement, respectively. Levodopa equivalence daily doses (LEDD), number of anti-PD medications and number of daily medication doses were used to measure improvements in medication burden. Data was evaluated using univariate analyses, one sample paired t-test, two sample paired t-test, and Wilcoxon signed-rank test.

RESULTS

The mean post-operative follow-up was 44.63 months, average age at diagnosis and the average age at time of DBS was 51.3 years and 61.5 years, respectively, and the time from diagnosis to treatment was 13.2 years. Significant decreases were seen in UPDRS III scores (pre-op = 44.533; post-op = 26.13; p = 0.0094), LEDD (pre-op = 1679.34 mg; post-op = 837.48 mg; p = 0.0049), and number of daily doses (pre-op = 21.266; post-op 12.2; p = 0.0046). No significant decrease was seen in the number of anti-PD medications (pre-op = 3.8; post-op = 3.2; p = 0.16).

CONCLUSION

Following DBS, severe PD patients demonstrated significant improvements in motor function and medication burden during long-term follow-up. We believe our results prove that DBS is efficacious in the management of severe PD, and that further research should follow to expand DBS criteria to include severe disease.

Early-morning OFF and levodopa dose failures in patients with Parkinson's disease attending a routine clinical appointment using Time-to-ON Questionnaire

BACKGROUND AND PURPOSE

In patients with Parkinson's disease (PD) with motor fluctuations, total daily OFF time is comprised of both end-of-dose time and the time taken to turn ON with medication. However, little is known about the impact of delays in ON time.

METHODS

This was a single-visit pilot study of fluctuating patients with PD attending a routine appointment. During a single visit, adult patients with idiopathic PD who were treated with levodopa for at least 1 year completed a questionnaire evaluating the time waiting for ON and the symptoms experienced while waiting to turn ON. Patients then completed a 5-day home time-to-ON diary, where they documented how long it took to turn ON following their first morning dose of levodopa in 5-min increments.

RESULTS

A total of 151 consecutive patients completed the study survey, of whom 97 (64.2%) experienced motor fluctuations. Of the patients experiencing motor fluctuations, 54 (56%) reported delays in ON time (latency >30 min) following their first morning dose of levodopa. Half (51%) reported that they had experienced delayed ON at least once in the previous week and 21% reported having delayed ON during all seven mornings of the previous week. In addition, 10% of patients reported having dose failures on four or more mornings during the previous week. The most common symptoms experienced while waiting for ON were slowness (94.8%), fatigue (87.6%), reduced dexterity (82.5%), problems in walking (66.0%) and problems with balance (59.8%).

CONCLUSION

Early-morning OFF problems such as delays in time to ON and dose failures are common in levodopa-treated patients with PD.

Adjunctive Therapies in Parkinson's Disease: How to Choose the Best Treatment Strategy Approach

End-of-dose motor fluctuations are regarded as one of the core troublesome symptoms by patients with Parkinson's disease (PD). Treatment of levodopa (L-dopa)-induced motor fluctuations is still an unmet medical need. L-dopa is the gold standard in the treatment of motor PD symptoms; notwithstanding, a wide range of adjunct therapies are currently available for the treatment of end-of-dose motor fluctuations. Additionally, device-aided therapies, such as deep brain stimulation, L-dopa-carbidopa intestinal gel infusion, and on-demand injection or continuous apomorphine infusion, may be considered when oral treatments are not sufficient to control motor fluctuations. In spite of the several evidence-based reviews and guidelines available, there is no agreement on which add-on therapy should be started first or its optimal timing. Equally challenging is the choice and timing between device-aided therapies. Herein, we propose a general overview of oral and device-aided treatments for PD patients with end-of-dose motor fluctuations, offering two possible algorithms that can guide clinicians during the therapeutic decision process.

Management of Fluctuating Parkinson’s Disease: From Science to Clinical Wisdom

This symposium took place at the 4th Congress of the European Academy of Neurology (EAN) 2018 in Lisbon, Portugal, and focussed on the effective management of fluctuating Parkinson’s disease (PD). Prof Poewe introduced the topic by explaining how response fluctuations, including wearing-off, remain a key priority in the effective management of PD. Wearing-off fluctuations are often categorised as motor or non-motor, but the reality is that patients are frequently affected by both, with a significant impact on daily activities and quality of life. Prof Stocchi went on to explain that management strategies include adjunct therapies with catechol-O-methyl transferase (COMT) inhibitors, monoamine oxidase (MAO)-B inhibitors, and dopamine agonists. Clinical experience shows that within a few years most patients will be receiving a cocktail of these drugs to manage PD symptoms. Although many antiparkinsonian drug classes have overlapping indications, they have distinct mechanisms of action that can complement each other. Opicapone is a third generation, highly potent and effective COMT inhibitor that received European Union (EU) market approval in 2016 as an adjunct to levodopa for PD patients experiencing response fluctuations. While the efficacy and safety of once-daily opicapone have been proven in clinical studies, Prof Ebersbach gave an overview of real-life data from his own clinics, which show that the benefits of opicapone can be observed within 3 days of treatment initiation. The final presentation from Dr Morgante considered the management of non-motor symptoms in PD. Classically, these non-motor symptoms have been managed as non-urgent symptoms but are now recognised as a significant source of disability. It is vital for clinicians to recognise that many of these symptoms respond to treatment.

The spectrum of "off" in Parkinson's disease: What have we learned over 40 years?

The terms "on" and "off" were used by Marsden and his contemporaries over 40 years ago to describe times when Parkinson's disease patients experienced good motor function ("on") and immobility ("off"). Yet there remains no published consensus definition of "off", leading clinicians and patients to develop individualized impressions of "off" determinations. In this paper, we first discuss the evolution of the terminology and understanding of "off" states since Marsden's time, which now include non-motor as well as motor symptoms. We then review pathophysiology and risk factors for the development of "off" states as well as tools to detect the "off" state, before proposing a practical definition of "off" for consideration. A common, practical definition of the "off" state could improve clinical recognition of "off" symptoms and lead to significant benefit for patients.

Opicapone for the management of end-of-dose motor fluctuations in patients with Parkinson's disease treated with L-DOPA

INTRODUCTION

Opicapone is a third generation, highly potent and effective catechol O‑methyltransferase (COMT) inhibitor that optimizes the pharmacokinetics and bioavailability of L-DOPA therapy. Areas covered: In this review, the authors describe the preclinical and clinical development of opicapone. In PD patients with motor fluctuations, once daily opicapone administration was well-tolerated and consistently reduced OFF-time and increased ON-time without increasing the frequency of troublesome dyskinesia, and these benefits were maintained over at least a year of continued open-label therapy. Expert commentary: With its convenient once-daily regimen, adjunct opicapone should be considered as an effective option for use in L-DOPA treated PD patients experiencing motor fluctuations.

Treatment of Older Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease. The prevalence of PD increases with age. The spectrum of clinical features, the rate of progression of the disease, the burden of nonmotor symptoms, and the response to medications are different in older patients with PD from the relatively younger patients. Management of symptoms of PD in older patients is challenging because of possible existence of several age-related systemic illness. While dealing with older patients, it is crucial not to attribute all the physical symptoms to PD. Thorough evaluation for existence of diseases such as normal pressure hydrocephalus and vascular parkinsonism which partially mimic the symptoms of PD carries immense importance. Medical management of parkinsonian symptoms should be preferred with levodopa monotherapy. However, in patients with significant motor fluctuations, dopaminergic agents may be added with caution, as they are notorious for several adverse reactions. Nonmotor symptoms must be provided high importance as they substantially worsen the quality of life. In addition to parkinsonian symptoms, older patients with PD may need to undergo surgery for several conditions. Meticulous perioperative management is crucial as older patients with PD may face several surgery-related complications compared to the younger patients. Compliance to treatment is an important issue in old age. Hence multidisciplinary approach to management of PD in older patients should be emphasized.

Investigation of different spectrophotometric and chemometric methods for determination of entacapone, levodopa and carbidopa in ternary mixture

New, simple, accurate and sensitive UV spectrophotometric and chemometric methods have been developed and validated for determination of Entacapone (ENT), Levodopa (LD) and Carbidopa (CD) in ternary mixture. Method A is a derivative ratio spectra zero-crossing spectrophotometric method which allows the determination of ENT in the presence of both LD and CD by measuring the peak amplitude at 249.9nm in the range of 1-20μgmL^-1. Method B is a double divisor-first derivative of ratio spectra method, used for determination of ENT, LD and CD at 245, 239 and 293nm, respectively. Method C is a mean centering of ratio spectra which allows their determination at 241, 241.6 and 257.1nm, respectively. Methods B and C could successfully determine the studied drugs in concentration ranges of 1-20μgmL^-1 for ENT and 10-90μgmL^-1 for both LD and CD. Methods D and E are principal component regression and partial least-squares, respectively, used for the simultaneous determination of the studied drugs by using seventeen mixtures as calibration set and eight mixtures as validation set. The developed methods have the advantage of simultaneous determination of the cited components without any pre-treatment. All the results were statistically compared with the reported methods, where no significant difference was observed. The developed methods were satisfactorily applied to the analysis of the investigated drugs in their pure form and in pharmaceutical dosage forms.

Multivalent approaches and beyond: novel tools for the investigation of dopamine D2 receptor pharmacology

The dopamine D2 receptor (D2R) has been implicated in the symptomology of disorders such as schizophrenia and Parkinson's disease. Multivalent ligands provide useful tools to investigate emerging concepts of G protein-coupled receptor drug action such as allostery, bitopic binding and receptor dimerization. This review focuses on the approaches taken toward the development of multivalent ligands for the D2R recently and highlights the challenges associated with each approach, their utility in probing D2R function and approaches to develop new D2R-targeting drugs. Furthermore, we extend our discussion to the possibility of designing multitarget ligands. The insights gained from such studies may provide the basis for improved therapeutic targeting of the D2R.

Short- and Long-Term Outcomes of Deep Brain Stimulation in Patients 70 Years and Older with Parkinson Disease

BACKGROUND

Parkinson disease (PD) is a common neurodegenerative disease in elderly patients that may be treated with deep brain stimulation (DBS). DBS is an accepted surgical treatment in PD patients <70 years that demonstrates marked improvement in disease symptomology. Patients ≥70 years historically have been excluded from DBS therapy. Our objective is to evaluate the short- and long-term outcomes in patients with PD ≥70 years who underwent DBS at our center.

METHODS

In our single-center study, we retrospectively assessed a prospective registry of patients with PD treated with DBS who were ≥70 years old at the time of their procedure. Univariate analyses and 1-sample paired t test were used to evaluate data. Motor scores were evaluated with the Unified Parkinson's Disease Rating Scale III, and the effects on medication requirements were evaluated with levodopa equivalence daily doses (LEDD).

RESULTS

Thirty-seven patients were followed for an average of 42.2 months post-DBS. The average ages at diagnosis and at the time of DBS surgery were 63.05 years and 72.45 years, respectively. Significant reductions in the average Unified Parkinson's Disease Rating Scale III score were observed (preoperative 31.8; postoperative 15.6; P < 0.0001). Significant reductions in the average LEDD (preoperative 891.94 mg; postoperative 559.6 mg; P = 0.0008) and medication doses per day (preoperative 11.54; postoperative 7.97; P = 0.0112) also were present.

CONCLUSION

DBS is effective in treating elderly patients with PD. Patients experienced improvement in motor function, LEDD, and medication doses per day after DBS. Our results suggest that DBS is an effective treatment modality in elderly patients with PD.

Apomorphine Subcutaneous Injection for the Management of Morning Akinesia in Parkinson's Disease

Background

In patients with motor fluctuations complicating Parkinson's disease (PD), delays in time‐to‐ON with levodopa are common. This open‐label study aimed to assess the effect of apomorphine on time‐to‐ON in PD patients with morning akinesia.

Methods

The safety population included 127 enrolled patients, and the full analysis set (FAS) included 88 patients. Patients completed a 7‐day levodopa baseline period recording their time‐to‐ON following each morning dose of levodopa. Patients were titrated to an optimal dose of apomorphine (2–6 mg) while taking trimethobenzamide antiemetic therapy. Apomorphine was injected each morning for a 7‐day treatment period and time‐to‐ON was self‐recorded in 5‐minute blocks. The primary efficacy variable was time‐to‐ON in the apomorphine treatment period versus the baseline levodopa period. Secondary assessments included and global impression scales. Safety and tolerability were assessed through adverse events (AEs).

Results

Patients receiving apomorphine achieved mean ± standard deviation (SD) time‐to‐ON 23.72 ± 14.55 minutes, reduced from 60.86 ± 18.11 minutes with levodopa (P < 0.0001). Dose failures (defined as time‐to‐ON >60 minutes) were more commonly reported with levodopa versus apomorphine (46% vs. 7% of diary entries, respectively).

Secondary endpoints supported the primary efficacy findings, with significant improvements from levodopa baseline to apomorphine treatment period (all P < 0.0001). The most common AEs were nausea and dizziness. Most patients who discontinued because of AEs did so in the titration phase.

Conclusions

Apomorphine injections significantly reduced time‐to‐ON in PD patients experiencing delayed onset of their morning levodopa dose, and was well tolerated in most patients. After apomorphine treatment, fluctuating patients with morning akinesia experienced rapid and reliable improvement of time‐to‐ON.

Health-related quality of life in Parkinson's: impact of 'off' time and stated treatment preferences

PURPOSE

Long-term levodopa therapy and related fluctuating plasma concentrations are associated with between-dose periods of 'off time' resulting in substantial variation in symptoms and functioning throughout the day in people with Parkinson's (PwP).

METHODS

PwP across UK, France, Spain and Italy completed an online survey to explore: the impact of 'off time' on (1) health-related quality of life (HRQL) and (2) on functioning and ability to undertake usual activities; (3) the value of 'off time' relative to other factors associated with Parkinson's through a stated preference discrete choice experiment (SPDCE).

RESULTS

In total, 305 PwP completed the online survey. Overall mean HRQL (utility) score was significantly lower for 'off time' (0.37) than for 'on time' (0.60). All attributes within the SPDCE were significant predictors of treatment choice, although increased duration of 'on time' (per hour per day: odds ratio (OR) = 1.40) and predictability of 'off time' to within 30 min (OR = 1.42) were valued most highly.

CONCLUSIONS

'On time' and predictability of 'off time' are highly valued by PwP. Due to substantial diurnal variation of Parkinson's symptoms, standard patient-reported outcome (PRO) assessments may not adequately capture the impact of 'off time' on HRQL and participation in daily activities.

L-Dopa Pharmacokinetic Profile with Effervescent Melevodopa/Carbidopa versus Standard-Release Levodopa/Carbidopa Tablets in Parkinson's Disease: A Randomised Study

Objectives. To characterize the pharmacokinetic profile of levodopa (L-dopa) and carbidopa after repeated doses of the effervescent tablet of melevodopa/carbidopa (V1512; Sirio) compared with standard-release L-dopa/carbidopa in patients with fluctuating Parkinson's disease. Few studies assessed the pharmacokinetics of carbidopa to date. Methods. This was a single-centre, randomized, double-blind, double-dummy, two-period crossover study. Patients received V1512 (melevodopa 100 mg/carbidopa 25 mg) or L-dopa 100 mg/carbidopa 25 mg, 7 doses over 24 hours (Cohort 1), 4 doses over 12 hours (Cohort 2), or 2 doses over 12 hours in combination with entacapone 200 mg (Cohort 3). Pharmacokinetic parameters included area under the plasma-concentration time curve (AUC), maximum plasma concentration (C_max), and time to C_max (t_max). Results. Twenty-five patients received at least one dose of study medication. L-dopa absorption tended to be quicker and pharmacokinetic parameters less variable after V1512 versus L-dopa/carbidopa, both over time and between patients. Accumulation of L-dopa in plasma was less noticeable with V1512. Carbidopa exposure and interpatient variability was lower when V1512 or L-dopa/carbidopa was given in combination with entacapone. Both treatments were well tolerated. Conclusions. V1512 provides a more reliable L-dopa pharmacokinetic profile versus standard-release L-dopa/carbidopa, with less drug accumulation and less variability. This trial is registered with ClinicalTrials.gov NCT00491998.

Co-operative binding assay for the characterization of mGlu4 allosteric modulators

The interest in the role of metabotropic glutamate receptor 4 (mGlu4) in CNS related disorders has increased the need for methods to investigate the binding of allosteric drug candidates. Our aim is to present the first fully characterized in vitro binding assay of mGlu4 positive allosteric modulators (PAMs). Results suggest that mGlu4 PAMs have characteristic co-operative binding with orthosteric glutamate, which offers a notable insight to the further development of mGlu4 targeted therapies.