Randomized trial of IPX066, carbidopa/levodopa extended release, in early Parkinson's disease

A Review of Levodopa Formulations for the Treatment of Parkinson's Disease Available in the United States

Purpose: The safety and efficacy of levodopa formulations are evaluated to inform clinical decision making for the treatment of Parkinson's disease. Summary: Levodopa is a cornerstone of treatment for Parkinson's disease due to its proven efficacy. Although many patients can initially be managed using immediate release tablets, as their disease progresses they often require escalating doses as well as more frequent dosing to prevent wearing off effects. Additionally, patients who experience time in the off state may struggle with the delay between medication administration and onset of action. Therefore, to increase patient convenience as well as to enhance the pharmacokinetic profile of the levodopa, several other formulations have been developed. Levodopa coformulated with carbidopa is supplied as immediate release tablets, oral disintegrating tablets, controlled release tablets, extended release capsules, and a continuous enteral solution. Additionally, there is a levodopa inhalation powder available. As a result of their different absorption profiles, each formulation has unique safety and efficacy attributes. Consequently, while this expansion of levodopa formulations has substantially increased treatment options for patients, it has also increased the complexity of medical decision making for patients, providers, and health systems alike. Conclusion: Knowledge of the different pharmacokinetic, safety and efficacy profiles of the available levodopa formulations is critical for the effective management of Parkinson's disease on both the individual patient and population levels.

Dose-response relationship of levodopa with dyskinesia in Parkinson's disease: A systematic review and meta-analysis

Despite existing evidence linking dyskinesia to levodopa, the primary treatment for Parkinson's, the dose-response relationship and risk factors remain uncertain. In this study, the risk for dyskinesia in patients with Parkinson's disease receiving levodopa was evaluated via meta-analysis and meta-regression approaches to examine dyskinesia risk factors more reliably and improve treatment strategies and patient care. The PubMed and Embase databases were searched to identify randomized controlled trials comparing levodopa with other anti-Parkinson's drugs published in English before June 31, 2023. The primary outcome was dyskinesia, and a risk of bias assessment was performed. In total, 24 studies met the inclusion criteria; 21 had a low risk of bias, and 3 had a high risk of bias. These studies included 4698 patients with Hoehn and Yahr Grade I-III Parkinson's disease. Our meta-analysis showed that the risk of dyskinesia was higher for levodopa than for other anti-Parkinson's drugs (odds ratio: 2.52 [95% confidence interval: 1.84-3.46]). Dyskinesia was not related to age (slope coefficient: 0.185 [0.095]; P = 0.061), disease duration (slope coefficient: 0.011 [0.018]; P = 0.566), or treatment duration (slope coefficient: 0.008 [0.007]; P = 0.216). The mean levodopa equivalent dose (slope coefficient: 0.004 [0.001]; P = 0.001) in the experimental group and the differences in drug doses between the experimental and control groups were correlated with the risk of dyskinesia. Results of randomized controlled trials supported an association between the levodopa dose and dyskinesia in patients with Parkinson's disease. Compared with levodopa users, users of other anti-Parkinson's drugs had a lower incidence of dyskinesia. Age, disease duration, and treatment duration were not correlated with dyskinesia. These findings suggest that anti-Parkinson's drugs other than levodopa, particularly in cases of early-stage Parkinson's disease, should be considered to reduce the risk of dyskinesia.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

The Management of Parkinson's Disease: An Overview of the Current Advancements in Drug Delivery Systems

Parkinson's disease (PD) has significantly affected a large proportion of the elderly population worldwide. According to the World Health Organization, approximately 8.5 million people worldwide are living with PD. In the United States, an estimated one million people are living with PD, with approximately 60,000 new cases diagnosed every year. Conventional therapies available for Parkinson's disease are associated with limitations such as the wearing-off effect, on-off period, episodes of motor freezing, and dyskinesia. In this review, a comprehensive overview of the latest advances in DDSs used to reduce the limitations of current therapies will be presented, and both their promising features and drawbacks will be discussed. We are also particularly interested in the technical properties, mechanism, and release patterns of incorporated drugs, as well as nanoscale delivery strategies to overcome the blood-brain barrier.

Temporal dynamics of cortical activity and postural control in response to the first levodopa dose of the day in people with Parkinson's disease

BACKGROUND

Our understanding of how balance control responds to levodopa over the course of a single day in people with Parkinson's disease (PD) is limited with the majority of studies focused on isolated comparisons of ON vs. OFF levodopa medication.

OBJECTIVE

To evaluate the temporal dynamics of postural control following the first levodopa dose of the day during a challenging standing task in a group of people with PD.

METHODS

Changes in postural control were evaluated by monitoring cortical activity (covering frontal, motor, parietal and occipital areas), body sway parameters (force platform), and lower limb muscle activity (tibialis anterior and gastrocnemius medialis) in 15 individuals with PD during a semi-tandem standing task. Participants were assessed during two 60 second trials every 30 minutes (ON-30 ON-60 etc.) for 3 hours after the first matinal dose (ON-180).

RESULTS

Compared to when tested OFF-medication, cortical activity was increased across all four regions from ON-60 to ON-120 with early increases in alpha and beta band activity observed at ON-30. Levodopa was associated with increased gastrocnemius medialis activity (ON-30 to ON-120) and ankle co-contraction (ON-60 to ON-120). Changes in body sway outcomes (particularly in the anterior-posterior direction) were evident from ON-60 to ON-120.

CONCLUSIONS

Our results reveal a 60-minute window within which postural control outcomes may be obtained that are different compared to OFF-state and remain stable (from 60-minutes to 120-minutes after levodopa intake). Identifying a window of opportunity for measurement when individuals are optimally medicated is important for observations in a clinical and research setting.

The effect and safety of levodopa alone versus levodopa sparing therapy for early Parkinson's disease: a systematic review and meta-analysis

BACKGROUND

The best choice between levodopa alone and levodopa sparing medications for early Parkinson's disease (PD) remains controversial. We aimed to evaluate the effect and safety of levodopa alone and levodopa sparing therapy in symptom relief, neuroimage results and complications.

METHODS

A systematic search was performed in PubMed, The Cochrane Library, EMBASE, and Web of Science for randomized controlled trials of early PD patients comparing levodopa-alone with levodopa-sparing therapy. The mean difference (MD) and the risk ratio (RR) were meta-analyzed.

RESULTS

Twenty-three articles with 4913 patients were included. Significantly greater benefit was detected for the levodopa group in the changes of Unified Parkinson's Disease Rating Scale part II (p < 0.00001), III (p < 0.00001), and total (p < 0.00001) scores, and the between-group MD in part III score increased over time. The loss of the radioligands uptake in levodopa-alone group was also increasingly greater over time. Patients treated with levodopa alone were at higher risk for wearing-off (p < 0.001) and dyskinesia (p < 0.001), but the RR for dyskinesia between the two groups decreased after 2 years of follow-up.

CONCLUSION

Levodopa-alone therapy might be superior in motor symptom relief than levodopa-sparing therapy for early PD patients, and the motor advantage of levodopa-alone might grow over time. Sparing therapy might be associated with less risk of wearing-off and dyskinesia, but the events between the two groups might not be different in the long run. Overall, levodopa alone therapy might bring more net benefit to early PD patients compared with levodopa sparing strategies. The clinical and imaging findings are conflicting, which requires further investigation.

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

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

Update on Parkinson's Disease Therapy

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

Parkinson's disease is a chronic, neurodegenerative disease, which manifests with a mixture of motor, cognitive and behavioural symptoms. Levodopa is the most effective antiparkinsonian treatment to date, although chronic use engenders a mixture of complications in a substantial proportion of patients. Amongst these is the occurrence of episodes of worsening symptoms-'off' phenomena. These episodes can manifest with either motor or non-motor symptoms or a combination of these features and have been found to have profound impacts on patients' quality of life. Although preventative measures are poorly evidenced, avoiding excessive total daily levodopa intake in selected populations that are deemed to be of a higher risk for developing these episodes warrants further exploration. Methods to improve levodopa bioavailability and delivery to the brain are currently available and are of value in addressing these episodes once they have become established. These include modifications to levodopa formulations as well as the use of complimentary agents that improve levodopa bioavailability. The deployment of device-assisted approaches is a further dimension that can be considered in addressing these debilitating episodes. This review summarises the clinical manifestations of 'off' phenomena and the current approaches to treat them. Although we briefly discuss clinical advances on the horizon, the predominant focus is on existing, established treatments.

Improving the Delivery of Levodopa in Parkinson's Disease: A Review of Approved and Emerging Therapies

Levodopa is the most effective drug for the treatment of Parkinson's disease, but its use as an oral medication is complicated by its erratic absorption, extensive metabolism and short plasma half-life. On long-term use and with disease progression, there is a high incidence of motor and non-motor complications, which remain a major clinical and research challenge. It is widely accepted that levodopa needs to be administered using formulations that result in good and consistent bioavailability and the physiologically relevant and continuous formation of dopamine in the brain to maximise its efficacy while avoiding and reversing 'wearing off' and dyskinesia. However, the physicochemical properties of levodopa along with its pharmacokinetic and pharmacodynamic profile make it difficult to deliver the drug in a manner that fulfils these criteria. In this review, we examine the problems associated with the administration of levodopa in Parkinson's disease and how the use of novel technologies and delivery devices is leading to a more consistent and sustained levodopa delivery with the aim of controlling motor function as well as non-motor symptoms.

Extracellular Vesicles as Nanotherapeutics for Parkinson's Disease

Extracellular vesicles (EVs) are naturally occurring membranous structures secreted by normal and diseased cells, and carrying a wide range of bioactive molecules. In the central nervous system (CNS), EVs are important in both homeostasis and pathology. Through receptor-ligand interactions, direct fusion, or endocytosis, EVs interact with their target cells. Accumulating evidence indicates that EVs play crucial roles in the pathogenesis of many neurodegenerative disorders (NDs), including Parkinson's disease (PD). PD is the second most common ND, characterized by the progressive loss of dopaminergic (DAergic) neurons within the Substantia Nigra pars compacta (SNpc). In PD, EVs are secreted by both neurons and glial cells, with either beneficial or detrimental effects, via a complex program of cell-to-cell communication. The functions of EVs in PD range from their etiopathogenetic relevance to their use as diagnostic tools and innovative carriers of therapeutics. Because they can cross the blood-brain barrier, EVs can be engineered to deliver bioactive molecules (e.g., small interfering RNAs, catalase) within the CNS. This review summarizes the latest findings regarding the role played by EVs in PD etiology, diagnosis, prognosis, and therapy, with a particular focus on their use as novel PD nanotherapeutics.

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.

Pharmacologic Treatment of Motor Symptoms Associated with Parkinson Disease

The cardinal motor features of Parkinson disease (PD) are driven by striatal dopamine deficiency. Pharmacologic dopamine substitution is the mainstay of drug treatment of PD. Levodopa is still the most efficacious drug to treat PD motor symptoms. MAO-B inhibitors and dopamine agonists are useful options. The main limitation of levodopa is the development of motor response fluctuations and drug-induced dyskinesias. Adjunct MAO-B and COMT inhibitors as well as dopamine agonists and continuous infusions of levodopa intestinal gel or subcutaneous apomorphine are efficacious in reducing motor fluctuations and amantadine is the only drug with established efficacy in reducing dyskinesias.

Dyskinesia matters

Levodopa-induced dyskinesia (LID) represents a significant source of discomfort for people with Parkinson's disease (PD). It negatively affects quality of life, it is associated with both motor and nonmotor fluctuations, and it brings an increased risk of disability, balance problems, and falls. Although the prevalence of severe LID appears to be lower than in previous eras (likely owing to a more conservative use of oral levodopa), we have not yet found a way to prevent the development of this complication. Advanced surgical therapies, such as deep brain stimulation, ameliorate LID, but only a minority of PD patients qualify for these interventions. Although some have argued that PD patients would rather be ON with dyskinesia than OFF, the deeper truth is that patients would very much prefer to be ON without dyskinesia. As researchers and clinicians, we should aspire to make that goal a reality. To this end, translational research on LID is to be encouraged and persistently pursued. © 2019 International Parkinson and Movement Disorder Society.

Pimavanserin versus quetiapine for the treatment of psychosis in Parkinson's disease and dementia with Lewy bodies

INTRODUCTION

Psychosis is common among patients with Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Limited data exist on the most effective therapies.

METHODS

Retrospective cohort study comparing patients with PD or DLB initiated on quetiapine or pimavanserin for psychosis. Primary outcome was time to discontinuation of pimavanserin or quetiapine using Kaplan-Meier survival analysis. We hypothesized the rate of antipsychotic discontinuation would be lower in the pimavanserin group. Subjects were included if the indication for treatment was psychosis and excluded if there was a history of major mental illness or no follow up data were available.

RESULTS

Forty-seven patients were included in the quetiapine cohort and 45 in the pimavanserin cohort. Patients in the pimavanserin cohort were more likely to have a diagnosis of DLB (33% vs. 11%, P = 0.01) and to have been prescribed an antipsychotic previously (62% vs. 6%, P < 0.01); otherwise, the groups were similar. Time to discontinuation analysis, which accounts for efficacy, safety and tolerability, revealed a lower early pimavanserin discontinuation rate and a higher late pimavanserin discontinuation rate (HR < 1 before day 43, HR > 1 after day 43; P = 0.04). There was no difference in mortality in the pimavanserin group compared to the quetiapine group (HR 0.37, 95% CI 0.06 to 2.45; P = 0.88). More individuals had a documented secondary indication for taking quetiapine than pimavanserin (38% vs. 4%; P = 0.001).

CONCLUSION

Accounting for efficacy, safety and tolerability, pimavanserin may be more clinically useful for promptly managing psychosis, while quetiapine may confer additional secondary benefits long-term.

Contemporary Options for the Management of Motor Complications in Parkinson's Disease: Updated Clinical Review

Parkinson's disease (PD) is a chronic, progressive condition affecting around 1% of the population older than 60 years. Upon long-term treatment with levodopa, the mainstay of treatment in PD, most patients, especially younger ones exposed to higher doses, will experience symptoms related to end-of-dose deterioration, peak-dose dyskinesias, and other motor fluctuations. Therapeutic strategies are grounded on modification of oral levodopa pharmacokinetics to extend levodopa benefit and development of new routes of drug delivery (e.g., levodopa/carbidopa intestinal gel infusion) or long-acting formulations of existing dopaminergic drugs to prolong the duration of striatal dopamine receptors stimulation. As our understanding of the pathophysiology of motor complications evolves, our therapeutic armamentarium is actively expanding and the focus of research is now actively pointing to the new non-dopaminergic agents acting both within the basal ganglia and in other brain regions (e.g., drugs acting on glutamate, GABA, serotonin, and calcium channels). Despite the fact that trials comparing the different therapeutic strategies are lacking, we aimed at devising practical evidence- and experience-guided suggestions for the clinical management of motor complications, emphasizing that this should always be an individualized endeavor. This review summarizes the pharmacological management of motor complications in PD, including new formulations and routes of delivery, and the newer released drugs such as istradefylline, opicapone, safinamide, and zonisamide. Advanced therapeutic strategies for selected cases such as treatment with apomorphine and surgical techniques (deep brain stimulation) are also discussed. A comprehensive knowledge of the available options and evidence is fundamental for the successful management of these challenging complications.

Management of Motor Features in Advanced Parkinson Disease

Advanced Parkinson disease (PD) is characterized by the presence of motor fluctuations becoming the focus of treatment, prominent postural instability, significant disability despite levodopa therapy, and the presence of symptoms refractory to levodopa therapy. In this article, the authors review the motor manifestations of patients with advanced PD, as well as the most common pharmacologic and nonpharmacologic available therapies.

Pharmacokinetics of Rytary®, An Extended-Release Capsule Formulation of Carbidopa-Levodopa

Parkinson's disease (PD) is a chronic progressive neurological disorder characterized by resting tremor, rigidity, bradykinesia, gait disturbance, and postural instability. Levodopa, the precursor to dopamine, coadministered with carbidopa or benserazide, aromatic amino acid decarboxylase inhibitors, is the most effective and widely used therapeutic agent in the treatment of PD. With continued levodopa treatment, a majority of patients develop motor complications such as dyskinesia and motor 'on-off' fluctuations, which are, in part, related to the fluctuations in plasma concentrations of levodopa. A new extended-release (ER) carbidopa-levodopa capsule product (also referred to as IPX066) was developed and approved in the US as Rytary^® and in the EU as Numient^®. The capsule formulation is designed to provide an initial rapid absorption of levodopa comparable to immediate-release (IR) carbidopa-levodopa, and to subsequently provide stable levodopa concentrations with reduced peak-to-trough excursions in plasma concentrations in order to reduce motor fluctuations associated with pulsatile stimulation of dopamine receptors and to minimize dyskinesia. Phase III studies of this ER carbidopa-levodopa capsule formulation in patients with PD have shown a significant reduction in 'off' time compared with IR carbidopa-levodopa and carbidopa-levodopa-entacapone. We present a review of the clinical pharmacokinetics and pharmacodynamics of this ER product of carbidopa-levodopa in healthy subjects and in patients with PD.

Onset and duration of effect of extended-release carbidopa-levodopa in advanced Parkinson's disease

BACKGROUND

In patients with Parkinson's disease (PD), oral dosing of extended-release carbidopa-levodopa (Rytary, IPX066 [ER CD-LD]) achieves peak levodopa plasma concentrations within 1 hour and maintains them for 4-6 hours.

AIMS

To compare the onset and duration of ER CD-LD benefit with those of immediate-release carbidopa-levodopa (IR CD-LD) in PD patients with motor fluctuations, using crossover data, and to evaluate which threshold values of improvement in finger-tapping and Unified Parkinson's Disease Rating Scale (UPDRS) motor scores yield results most similar to those for trained raters' "on"/"off" assessments.

METHODS

Patients underwent serial "on"/"off" rating and provided serial finger-tapping and UPDRS motor scores after receiving, in an "off" state, their usual morning IR dose or an ER dose designed to produce a similar levodopa peak concentration. Predefined improvement thresholds for analysis were 10%, 15%, and 20% increases in finger-tapping score and 2.5, 5, 7, and 11-point decreases in UPDRS motor score. Serial plasma samples were assayed for levodopa.

RESULTS

Among 27 patients, mean time to onset of an "on" state was similar for ER compared with IR CD-LD (0.83 vs 0.81 hour), but mean duration was significantly longer for ER CD-LD than for IR CD-LD (5.56 vs 2.69 hours; P<0.0001). Duration was best matched by a $20% improvement in finger-tapping, a $11-point improvement in UPDRS motor score, and a levodopa plasma concentration $1,000 ng/mL.

CONCLUSION

For ER CD-LD, observer assessments of "on" state were corroborated by sustained treatment effects. Correlations among "on"-state duration, finger-tapping score, and UPDRS motor score may suggest clinically relevant thresholds for acute assessment of treatment benefit.

Levodopa in Parkinson's Disease: Current Status and Future Developments

BACKGROUND

Ever since the pioneering reports in the 60s, L-3,4-Dioxyphenylalanine (levodopa) has represented the gold standard for the treatment of Parkinson's Disease (PD). However, long-term levodopa (LD) treatment is frequently associated with fluctuations in motor response with serious impact on patient quality of life. The pharmacokinetic and pharmacodynamic properties of LD are pivotal to such motor fluctuations: discontinuous drug delivery, short half-life, poor bioavailability, and narrow therapeutic window are all crucial for such fluctuations. During the last 60 years, several attempts have been made to improve LD treatment and avoid long-term complications.

METHODS

Research and trials to improve the LD pharmacokinetic since 1960s are reviewed, summarizing the progressive improvements of LD treatment.

RESULTS

Inhibitors of peripheral amino acid decarboxylase (AADC) have been introduced to achieve proper LD concentration in the central nervous system reducing systemic adverse events. Inhibitors of catechol-O-methyltransferase (COMT) increased LD half-life and bioavailability. Efforts are still being made to achieve a continuous dopaminergic stimulation, with the combination of oral LD with an AADC inhibitor and a COMT inhibitor, or the intra-duodenal water-based LD/ carbidopa gel. Further approaches to enhance LD efficacy are focused on new non-oral administration routes, including nasal, intra-duodenal, intrapulmonary (CVT-301) and subcutaneous (ND0612), as well as on novel ER formulations, including IPX066, which recently concluded phase III trial.

CONCLUSION

New LD formulations, oral compounds as well as routes have been tested in the last years, with two main targets: achieve continuous dopaminergic stimulation and find an instant deliver route for LD.

Extended-release oral capsule of carbidopa-levodopa in Parkinson disease

Motor fluctuations complicate the treatment of patients with Parkinson's disease receiving levodopa. Extended-release carbidopa-levodopa has a pharmacokinetic profile that provides a more continuous levodopa serum concentration. Patients taking this formulation can expect longer duration of action and fewer doses per day, similar clinical improvement when compared to other levodopa formulations, and with a theoretically lower risk of developing motor fluctuations. Several studies, including three randomized control trials provide evidence for the efficacy, safety and tolerability of extended release carbidopa-levodopa in patients with both early and advanced Parkinson's disease are reviewed here. Also provided is guidance for dosing of and conversion to extended release carbidopa-levodopa as well as a discussion of its place in the clinical practice.

Large-scale identification of clinical and genetic predictors of motor progression in patients with newly diagnosed Parkinson's disease: a longitudinal cohort study and validation

Background

Better understanding and prediction of PD progression could improve disease management and clinical trial design. We aimed to use longitudinal clinical, molecular, and genetic data to develop predictive models, compare potential biomarkers, and identify novel predictors for motor progression in PD. We also sought to assess the use of these models in the design of treatment trials in PD.

Methods

A Bayesian multivariate predictive inference platform was applied to data from the Parkinson’s Progression Markers Initiative (PPMI) study (NCT01141023). We used genetic data and baseline molecular and clinical variables from PD patients and healthy controls to construct an ensemble of models to predict the annualised rate of the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale parts II and III combined. We tested our overall explanatory power, as assessed by the coefficient of determination (R²), and replicated novel findings in an independent clinical cohort of PD patients from the Longitudinal and Biomarker Study in PD (LABS-PD; NCT00605163). The potential utility of these models for clinical trial design was quantified by comparing simulated randomized placebo-controlled trials within the out-of sample LABS-PD cohort.

Findings

A total of 117 controls and 312 PD cases were available for analysis. Our model ensemble exhibited strong performance in-cohort (5-fold cross-validated R²=41%, 95% CI: 35% – 47%) and significant, though reduced, performance out-of-cohort (R²=9%, 95% CI: 4% – 16%). Individual predictive features identified from PPMI data were confirmed in the LABS-PD cohort of 317 PD patients. These included significant replication of higher baseline motor score, male sex, and increased age, as well as a novel PD-specific epistatic interaction all indicative of faster motor progression. Genetic variation was the most useful predictive marker of motor progression (2.9%, 95%CI: 1.5–4.3%). CSF biomarkers at baseline showed a more modest (0.3%; 95%CI: 0.1–0.5%), but still significant effect on motor progression prediction. The simulations (n=5000) showed that incorporating the predicted rates of motor progression into the final models of treatment effect reduced the variability in the study outcome allowing significant differences to be detected at sample sizes up to 20% smaller than in naïve trials.

Interpretation

Our model ensemble confirmed established and identified novel predictors of PD motor progression. Improving existing prognostic models through machine learning approaches should benefit trial design and evaluation, as well as clinical disease monitoring and treatment.

Funding

Michael J. Fox Foundation for Parkinson’s Research and National Institute of Neurological Disorders and Stroke (1P20NS092529-01).

Motor Complications of Dopaminergic Medications in Parkinson's Disease

Motor complications are a consequence of the chronic treatment of Parkinson's disease (PD) and include motor fluctuations (wearing-off phenomenon) and levodopa-induced dyskinesia. Both can have a significant impact on functionality and quality of life; thus, proper recognition and management is essential. The phenomenology and temporal relationship of motor complications to the schedule of levodopa dosing can be helpful in characterizing them. There are several therapeutic approaches to motor complications, including pharmacological and surgical options. The authors summarize the different types of motor complications according to phenomenology and the currently available medical treatments, including ongoing trials for the management of this condition.

Comparison for Efficacy and Tolerability among Ten Drugs for Treatment of Parkinson's Disease: A Network Meta-Analysis

Parkinson’s disease (PD) is a long term disorder affects the central nervous system and we aim to determine the relative efficacy of the current available drugs used in PD. Firstly, we performed a systematic review in current literature and eligible studies were retrieved from online databases, relevant data were extracted. Efficacy of these medications was assessed by different Unified Parkinson’s Disease Rating Scales (UPDRS). Mean difference (MD) and odds ratio (OR) were produced by pairwise or network meta-analysis (NMA). Finally, we performed a cluster analysis for the included medications with respect to their surface under the cumulative ranking curve (SUCRA). Pairwise meta-analysis suggests that selegiline had a higher ranking in UPDRS II, UPDRS III and UPDRS total than bromocriptine and levodopa. Selegiline was more tolerable than bromocriptine (OR = 0.62, CI: 0.39 to 0.98) and pramipexole was less tolerable than levodopa (OR = 1.43, CI = 1.00 to 2.04). Results of NMA indicate that patients with levodopa, pramipexole, ropinirole and selegiline exhibited a significantly improved UPDRS III than those with lazabemide. To sum up, levodopa, selegiline, ropinirole and rotigotine were recommended for PD patients as they appeared relatively high efficacy and tolerability.

Recent advances in treating Parkinson's disease

This article summarizes (1) the recent achievements to further improve symptomatic therapy of motor Parkinson’s disease (PD) symptoms, (2) the still-few attempts to systematically search for symptomatic therapy of non-motor symptoms in PD, and (3) the advances in the development and clinical testing of compounds which promise to offer disease modification in already-manifest PD. However, prevention (that is, slowing or stopping PD in a prodromal stage) is still a dream and one reason for this is that we have no consensus on primary endpoints for clinical trials which reflect the progression in prodromal stages of PD, such as in rapid eye movement sleep behavior disorder (RBD) —a methodological challenge to be met in the future.

Drug-Induced Dyskinesia, Part 1: Treatment of Levodopa-Induced Dyskinesia

Dyskinesias encompass a variety of different hyperkinetic phenomenologies, particularly chorea, dystonia, stereotypies, and akathisia. Levodopa-induced dyskinesia (LID) is one of the main types of drug-induced dyskinesia, occurring in patients with Parkinson's disease (PD) who have been treated with levodopa for long time, but this side effect may be encountered even within a few weeks or months after initiation of levodopa therapy. Based on the temporal pattern in relationship to levodopa dosing, LIDs are divided into "peak-dose dyskinesia," "diphasic dyskinesia," and "wearing off" or "off-period" dyskinesia, of which peak-dose dyskinesia is the most common, followed by off-period, and then diphasic dyskinesia. Treatment strategy includes identifying the kind of dyskinesia and tailoring treatment accordingly. Peak-dose dyskinesia is treated mainly by reducing individual doses of levodopa and adding amantadine and dopamine agonists, whereas off-period dystonia often responds to baclofen and botulinum toxin injections. Diphasic dyskinesias, occurring particularly in patients with young-onset PD, are the most difficult to treat. While fractionation of levodopa dosage is the most frequently utilized strategy, many patients require deep brain stimulation to control their troublesome motor fluctuations and LIDs. A variety of emerging (experimental) drugs currently in development promise to provide better control of LIDs and other levodopa-related complications in the near future.

Treatment Strategies in Early Parkinson's Disease

The clinicians' approach to the treatment of early Parkinson's disease (PD) should take into account numerous aspects, including how to inform a patient upon diagnosis and the critical decision of what therapy to adopt and when to start it. The treatment of the motor disorder associated with early PD needs to consider several crucial factors, such as age at onset, comorbidities, and the patient's functional requirements, and cannot be summarized in a simple formula. In younger patients (i.e., before the age of 70) and in those without high functional requirements, treatment is usually initiated with dopamine agonists and/or monoamine oxidase-B enzyme inhibitors (MAO-B I). By contrast, in older patients, or in those with high functional requirements, low doses of levodopa are generally used when treatment is started. In younger patients, levodopa should be added to dopamine agonists and/or MAO-B I, as required by disease progression, whereas in older patients, when response to levodopa alone is not satisfactory, dopamine agonists or catechol-O-methyltransferase inhibitors may subsequently be added.

Current Pharmaceutical Treatments and Alternative Therapies of Parkinson's Disease

Over the decades, pharmaceutical treatments, particularly dopaminergic (DAergic) drugs have been considered as the main therapy against motor symptoms of Parkinson's disease (PD). It is proposed that DAergic drugs in combination with other medications, such as monoamine oxidase type B inhibitors, catechol-O-methyl transferase inhibitors, anticholinergics and other newly developed non-DAergic drugs can make a better control of motor symptoms or alleviate levodopa-induced motor complications. Moreover, non-motor symptoms of PD, such as cognitive, neuropsychiatric, sleep, autonomic and sensory disturbances caused by intrinsic PD pathology or drug-induced side effects, are gaining increasing attention and urgently need to be taken care of due to their impact on quality of life. Currently, neuroprotective therapies have been investigated extensively in pre-clinical studies, and some of them have been subjected to clinical trials. Furthermore, non-pharmaceutical treatments, including deep brain stimulation (DBS), gene therapy, cell replacement therapy and some complementary managements, such as Tai chi, Yoga, traditional herbs and molecular targeted therapies have also been considered as effective alternative therapies to classical pharmaceutics. This review will provide us updated information regarding the current drugs and non-drugs therapies for PD.

Critical Analysis of Cardiovascular and Central Nervous System Fixed Dose Combinations Available in Indian Market

INTRODUCTION

Fixed Dose Combinations (FDCs) are being increasingly used to improve compliance and achieve greater benefits of the two or more active ingredients given together than the corresponding individual drug components given separately.

AIM

To analyse the rationality of Cardiovascular (CV) and Central Nervous System (CNS) FDCs available in Indian market.

MATERIALS AND METHODS

CVS and CNS FDCs, enlisted in Indian Drug Review, 2014, were analysed by a pretested validated eight point criteria tool. Each FDC was assessed for number of active pharmacological ingredients, approval by regulatory authority, listing in WHO Essential Medicine List. While efficacy, safety, pharmacokinetic, pharmacodynamic interactions and advantages of each FDC were analysed by literature search. The total score of the tool was 12 and score ≥7 was considered rational. FDCs were divided in four groups as per rationality and DCGI approval. ANOVA was used for statistical analysis and p<0.05 was considering statistically significant.

RESULTS

Out of 152 FDCs, 107 were CV and 45 belonged to CNS group and 40 had documented evidence of efficacy and safety. Majority of FDCs showed advantage of being convenient by reducing pill count and only 32 showed reducing adverse drug reactions. Out of 107 CV FDCs, 46 were rational and 61 were irrational with a mean rationality score of 6.72±2.82 (CI- 95 %, 3.90 - 9.54). While out of 45 CNS FDCs, 8 were rational and 37 were irrational with a mean rationality score of 6.22±2.08 (CI - 95 %, 4.14 - 8.30). A significant difference in mean rationality score of group A (DCGI approved + rational) was observed as compared to group B (DCGI approved + irrational) and group C (DCGI unapproved + rational) as compared to group D (DCGI unapproved + irrational) (p<0.05).

CONCLUSION

The absence of watertight pre-requisite, critical analysis of the scientific validity of the formulations and 'convenience' category has resulted into proliferation of irrational FDCs. This calls for strict regulatory approval process to avoid miserable FDC scenario in the country.

Optimizing extended-release carbidopa/levodopa in Parkinson disease: Consensus on conversion from standard therapy

Purpose of review:

To help clinicians optimize the conversion of a patient's Parkinson disease pharmacotherapy from immediate-release carbidopa/levodopa (IR CD/LD) to an extended-release formulation (ER CD/LD).

Recent findings:

Eleven movement disorders specialists achieved consensus positions on the modification of trial-based conversion guidelines to suit individual patients in clinical practice.

Summary:

Because the pharmacokinetics of ER CD/LD differ from those of IR CD/LD, modification of dosage and dosing frequency are to be expected. Initial regimens may be based on doubling the patient's preconversion levodopa daily dosage and choosing a division of doses to address the patient's motor complications, e.g., wearing-off (warranting a relatively high ER CD/LD dose, possibly at a lower frequency than for IR CD/LD) or dyskinesia (warranting a relatively low dose, perhaps at an unchanged frequency). Patients should know that the main goal of conversion is a steadier levodopa clinical response, even if dosing frequency is unchanged.

Novel Levodopa Formulations for Parkinson's Disease

Levodopa remains the most effective treatment for Parkinson's disease and is considered the gold standard therapy. However, disease progression and changes in the gastrointestinal tract result in a declining window of treatment response in a majority of patients. Efforts have been made recently to improve levodopa bioavailability either by developing more effective oral formulations or by innovating routes of administration (intestinal infusion, transcutaneous or inhaled levodopa). IPX066 is a novel levodopa-carbidopa (LD/CD) oral formulation combining immediate-release (IR) and extended-release (ER) LD/CD recently approved in the USA and the EU. Levodopa-carbidopa intestinal gel (LCIG) is an approved therapy consisting of a suspension of levodopa and carbidopa infused directly into the proximal jejunum via a percutaneous endoscopic gastrojejunostomy (PEG-J) tube through a portable infusion pump. Ongoing studies are evaluating the 'accordion pill' (AP09004), an ER LD/CD formulation with gastroretentive properties. ND0612 is a proprietary liquid formulation of LD/CD that enables subcutaneous administration via a small patch-pump device, and CVT-301 is a levodopa inhalation powder with rapid onset of action; both are currently in active studies. Other novel formulations have been discontinued, including DM-1992, which is a bilayer formulation containing an IR LD/CD layer and an ER LD/CD layer with gastroretentive properties, and XP21279, a novel oral levodopa prodrug that is absorbed from the small and large intestine by high-capacity nutrient transporters expressed throughout the gastrointestinal system. ODM-101 is a new oral formulation of levodopa/carbidopa/entacapone that contains a higher amount of carbidopa (65 or 105 mg), but no active studies are underway. The current review aims to summarize the pharmacokinetic aspects, clinical efficacy, and potential adverse events of novel levodopa formulations currently available or under development.

Clinical Pharmacokinetics of IPX066: Evaluation of Dose Proportionality and Effect of Food in Healthy Volunteers

Objectives

IPX066 is an oral, extended-release capsule formulation of carbidopa-levodopa (CD-LD) available in 4 strengths. The goals of this investigation were to assess the dose proportionality of IPX066 and to study the effects of a high-fat, high-calorie meal and of sprinkling the capsule contents on applesauce on the pharmacokinetics of IPX066 in healthy volunteers.

Methods

Three open-label studies were conducted. In the first study, subjects received 1 capsule of each IPX066 strength (23.75–95, 36.25–145, 48.75–195, and 61.25–245 mg of CD-LD). In the second study, subjects received 1 and 2 capsules of IPX066 245-mg LD under fasting conditions. In the third study, subjects received 2 capsules of IPX066 245-mg LD under 3 conditions: fasting; following a high-fat, high-calorie breakfast; and with the capsule contents sprinkled on applesauce under fasting conditions.

Results

Peak plasma concentrations (C_max) and systemic exposure (AUC_t, AUC_inf) for LD and CD increased dose-proportionally over the range of the IPX066 capsule strengths. Comparison of 1 and 2 IPX066 245-mg LD capsules showed dose-proportional pharmacokinetics for C_max and AUC_t. Sprinkling the capsule contents on applesauce did not affect the pharmacokinetics. A high-fat, high-calorie meal delayed the initial increase in LD concentration by approximately 1 to 2 hours, reduced C_max by 21%, and increased AUC_inf by 13% compared with the fasted state.

Conclusions

IPX066 shows dose-proportional pharmacokinetics. Sprinkling the capsule contents on applesauce does not affect the pharmacokinetics; a high-fat, high-calorie meal delayed absorption by 1 to 2 hours, slightly reduced C_max, and slightly increased extent of absorption.

Pharmacotherapy and generic health-related quality of life in Parkinson's disease

OBJECTIVES

Improvement of health-related quality of life (HRQoL) is one of the primary objectives of symptomatic therapies in Parkinson's disease (PD). The aim of this observational study was to investigate possible changes in generic HRQoL in relation to changed PD pharmacotherapy in the clinical setting.

MATERIALS & METHODS

A total of 219 outpatients with mild to moderate PD (median H&Y score = 2.0), treated with oral antiparkinsonian medications, were investigated twice with a 6-month interval. At baseline, PD medication dose was increased for 82 patients for clinical reasons (median increase of 100 mg levodopa equivalent daily dose or 31.9%), whereas medication remained unchanged for 137 patients. Two generic HRQoL questionnaires, EQ-5D and 15D, were used at baseline and at 6 months, and the baseline and delta HRQoL values were compared between the treatment groups.

RESULTS

In the entire sample, the EQ-VAS score decreased during the study period, indicating a general decline in HRQoL (P = 0.04). There were no differences in the baseline HRQoL values or delta values between the treatment groups as measured with EQ-5D or 15D (levodopa dose elevated vs dopamine agonist/MAO-B inhibitor dose elevated vs no change in medication).

CONCLUSIONS

An approximately 1/3 increase in antiparkinsonian medication dose did not have an impact on generic HRQoL. Disease-specific QoL may be more sensitive to pharmacotherapy-related changes in PD.

Dose-Response Analysis of the Effect of Carbidopa-Levodopa Extended-Release Capsules (IPX066) in Levodopa-Naive Patients With Parkinson Disease

Parkinson disease is an age-related disorder of the central nervous system principally due to loss of dopamine-producing cells in the midbrain. Levodopa, in combination with carbidopa, is widely regarded as an effective treatment for the symptoms of Parkinson disease. A dose-response relationship is established for carbidopa-levodopa extended-release capsules (IPX066) in levodopa-naive Parkinson disease patients using a disease progression model. Unified Parkinson Disease Rating Scale (UPDRS) part II plus part III scores from 171 North American patients treated with placebo or IPX066 for approximately 30 weeks from a double-blind, parallel-group, dose-ranging study were used to develop the pharmacodynamic model. The model comprised 3 components: a linear function describing disease progression, a component describing placebo (or nonlevodopa) effects, and a component to describe the effect of levodopa. Natural disease progression in early Parkinson disease as measured by UPDRS was 11.6 units/year and faster in patients with more severe disease (Hoehn-Yahr stage 3). Maximum placebo/nonlevodopa response was 23.0% of baseline UPDRS. Maximum levodopa effect from IPX066 was 76.7% of baseline UPDRS, and the ED50 was 450 mg levodopa. Equilibration half-life for the effect compartment was 62.8 days. Increasing age increased and being female decreased equilibration half-life. The quantitative model allowed description of the entire time course of response to clinical trial intervention.

Movement Disorders: A Brief Guide in Medication Management

Movement disorders can be challenging to manage and often use a specific set of medications. Because it is a complex and broad field within neurology, many providers are unfamiliar with the classes of medications. This paper details medications used for specific conditions, explains why these medications are helpful, and shares pearls and pitfalls related to each agent, focusing on parameters such as dose titration, side effect profiles, and specific drug-drug interactions and challenges. We focus on the most commonly encountered movement disorders, including essential tremor, Parkinson's disease, rapid eye movement sleep behavior disorder, and restless leg syndrome.

Asymmetric responsiveness of disability and health-related quality of life to improvement versus decline in Parkinson's disease

PURPOSE

Clinical trials in Parkinson's disease commonly employ outcome measures of disability and quality of life. Responsiveness of these outcomes measures to symptomatic decline versus improvement has not been studied. We wanted to study the responsiveness of Schwab & England Activities of Daily Living Scale (SE) and Short Form-12 (SF-12) to symptomatic decline versus improvement in Parkinson's disease over a 4-year period among a naturalistic cohort of patients.

METHODS

Parkinson's disease patients (N = 228, disease duration 6.1 years) were followed for 4 years with assessments of disease severity, Unified Parkinson's Disease Rating Scale (UPDRS), health-related quality of life (SF-12 physical/mental health), and disability (SE). The sample was subdivided into those who declined (N = 118) or improved (N = 102) on total-UPDRS. Responsiveness was assessed with Cohen's effect size and standardized response mean.

RESULTS

At baseline, patients who improved over 4 years had greater disease severity and worse quality of life than decliners (p < .05). Decliners had a 13.5-point worsening on total-UPDRS, 26.3-39.8; p < .001) associated with concomitant decline on the SF-12 (physical health 42.9-39.2, mental health 50.0-46.6; both p < .001) and the SE (85-74 %; p < .001). Improvers had a 13.0-point improvement on total-UPDRS (39.8-26.8; p < .001) associated with minimal change on the SF-12 (physical health 40.8-39.5, mental health 47.1-46.3) and SE (79-79 %). Based on effect size, the rank order of responsiveness of measures for decliners from high to low was SE (-0.78), Short Form-12 mental health (-0.45), and SF-12 physical health (-0.34). Rank order of responsiveness for improvers was Short Form-12 physical health (-0.11), SF-12 mental health (-0.10), and SE (-0.03).

CONCLUSIONS

Among decliners, measures of disability and quality of life were moderate to highly responsive to change in disease severity. Among improvers, both disability and quality of life were poorly responsive despite UPDRS improvement of comparable magnitude.

Clinical Response of Levodopa Carbidopa Combination in Patients with Idiopathic Parkinsonism

INTRODUCTION

Parkinson's disease is the most common form of a group of progressive neurodegenerative disorders. The use of levodopa as dopamine - replacement therapy is highly effective in ameliorating the symptoms of the disease and remains the standard drug with which other therapies are compared.

AIM

To study the change in Unified Parkinson's Disease Rating scale (UPDRS) scores in patients receiving levodopa and carbidopa treatment (levodopa- carbidopa combination).

MATERIALS AND METHODS

Study was conducted in Department of Neurology, Government Medical College, Trivandrum, India on 75 patients. All patients diagnosed with Idiopathic Parkinson's disease (PD) satisfying inclusion criteria were enrolled into the study. Informed written consent was taken from all patients. Baseline UPDRS scores were recorded followed by reassessment at the end of six month. Data was analysed using paired t-test with help of SPSS-16 statistical software.

RESULTS

Baseline UPDRS was collected and after 6 months of treatment, it was reassessed. Baseline total score was 49.8; the follow-up score was 39.5. A decrease in score was seen in various components of UPDRS.

CONCLUSION

Upon statistical analysis this difference was found to be significant, which implies that, there is improvement in patient's condition. Improvement was noted in Mentation, behaviour, mood, activities of daily living and motor functions. Hence there is positive treatment response for levodopa carbidopa therapy in patients with idiopathic PD.

Levodopa-Carbidopa Intestinal Gel in Patients with Parkinson's Disease: A Systematic Review

BACKGROUND

Levodopa-carbidopa intestinal gel (LCIG) is available in several countries for the treatment of advanced levodopa-responsive Parkinson's disease (PD) with severe motor fluctuations and dyskinesia when other treatments have not given satisfactory results.

OBJECTIVE

Our objective was to summarize the present evidence base for LCIG therapy through a systematic review of the literature.

METHODS

Studies were identified from the PubMed and EMBASE databases up to 12 March 2016 using the following search terms: Parkinson disease, duodopa, levodopa/carbidopa intestinal gel, levodopa-carbidopa intestinal gel, LCIG, l-dopa infusion, levodopa infusion, duodenal l-dopa infusion, and duodenal levodopa infusion. Data extraction focused on whether LCIG therapy improves motor and non-motor outcomes as well as quality of life in PD patients compared with conventional therapy, apomorphine infusion, or deep brain stimulation. Randomized controlled trials (RCTs) and observational studies, with or without a control group, that included more than ten patients were included. The search was limited to peer-reviewed articles published in full in the English language and involving humans.

RESULTS

Infusion of LCIG reduced "off" time, increased "on" time without increasing troublesome dyskinesias, and improved quality of life in three RCTs (one double-blind). Open-label follow-ups confirm these findings. The data evaluating long-term efficacy and safety are still limited.

CONCLUSIONS

The quality of evidence that LCIG is effective in reducing fluctuating motor symptoms and improving quality of life is moderate. Quality of evidence for reduction of non-motor symptoms is very low. Safety issues mainly relate to the intestinal infusion system. LCIG might be a useful treatment option in PD patients with severe motor fluctuations.

Physicians' experience with RYTARY (carbidopa and levodopa) extended-release capsules in patients who have Parkinson disease

A discussion between Dr. Dee Silver and Dr. Richard Trosch provides insight and advice for physicians considering a switch from immediate-release carbidopa-levodopa (IR CD-LD) to RYTARY as a treatment for patients with Parkinson disease (PD). The dialogue describes how they identify patients with PD who may and may not be successful switching to RYTARY, how they approach the conversion process and patient compliance, and how they address some side effects that may occur after patients begin taking RYTARY. The clinicians also discuss their experiences with how long it takes to establish a stable regimen as well as provide general advice regarding conversion from treatment with IR CD-LD to RYTARY.

A review of current and novel levodopa formulations for the treatment of Parkinson's disease

Parkinson's disease treatment is characterized by the nearly inevitable development of motor complications, including fluctuations and dyskinesias, in which the duration of benefit of a dose of medication is offset by involuntary movements that can be more disabling than the Parkinsonian features themselves. While levodopa remains the gold standard of therapy, it is the most likely to be associated with these complications. The concept of continuous dopaminergic stimulation has gained increasing acceptance as a potential mechanism by which to avoid or delay the development of motor complications, or to minimize their impact once they have already occurred. This article will explore existing and novel formulations of levodopa to identify their role in the spectrum of Parkinson's disease therapeutics.

New and emerging medical therapies in Parkinson's disease

INTRODUCTION

Parkinson's disease (PD) is one of the most challenging neurodegenerative disorders to treat as it manifests with a large variety of troublesome, and often disabling, motor and non-motor symptoms. Despite limitations, such as motor and other complications, levodopa remains the most effective drug in the treatment of PD.

AREAS COVERED

In this review, we focus on phase 2 and 3 studies describing new and emerging medical therapies in PD. We discuss new formulations of levodopa, medications that prolong levodopa response and ameliorate levodopa-induced dyskinesias, and innovative delivery methods that are currently being evaluated in clinical trials or are in development with the promise of better efficacy and tolerability. We also describe novel non-dopaminergic drugs that have been identified for treatment of motor and non-motor symptoms. A specific section is designated for potential disease modifying therapies.

EXPERT OPINION

Alternative formulations of levodopa appear to be promising especially to help with the motor fluctuations either by providing sustained benefits with controlled released formulations or ameliorate sudden OFF by formulations such as inhaled levodopa. Several different medications affecting non-dopaminergic pathways are being evaluated which may aide levodopa. As the understanding of the disease grows further, numerous novel neuroprotective or disease modifying therapies have been suggested. This along with development of medications to treat various non-motor symptoms will help improve quality of life of patients with PD.

Carbidopa/Levodopa ER Capsules (Rytary(®), Numient™): A Review in Parkinson's Disease

A new extended-release (ER) capsule formulation of carbidopa/levodopa (Rytary(®), Numient™, IPX066) is available for the treatment of Parkinson's disease (PD). Carbidopa/levodopa ER capsules contain beads of carbidopa and levodopa, designed to release the drugs at different rates in the gastrointestinal tract and provide constant therapeutic levodopa concentrations that are maintained for 4-5 h (after an initial peak at ≈ 1 h). In randomized phase III trials, oral carbidopa/levodopa ER was significantly more effective than placebo with regard to improving motor symptoms and activities of daily living in patients with early PD after 30 weeks' treatment, and provided significantly greater reductions in daily 'off-time' in patients with advanced PD than immediate-release (IR) carbidopa/levodopa or carbidopa/levodopa IR plus entacapone after a treatment period of 13 and 2 weeks, respectively, without increasing troublesome dyskinesia. The efficacy of carbidopa/levodopa ER was maintained during a 9-month open-label extension in patients with early or advanced PD. Carbidopa/levodopa ER was generally well tolerated in clinical trials, with the most common adverse events in the extension study being nausea and insomnia in patients with early PD and falls and dyskinesia in patients with advanced PD. Thus, carbidopa/levodopa ER is an effective and generally well-tolerated treatment option for the motor symptoms of PD, reducing periods of 'off-time' compared with carbidopa/levodopa IR without increasing troublesome dyskinesia.