A randomized trial of inhaled levodopa (CVT-301) for motor fluctuations in Parkinson's disease

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

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

METHODOLOGY

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

RESULTS

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

CONCLUSION

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

Sublingual apomorphine in treatment of Parkinson's disease: a review

PURPOSE

A majority of advanced Parkinson's disease (PD) patients on oral levodopa experience motor fluctuations, including sudden OFF and delayed ON periods. Fast-acting rescue medications are a vital part of the clinician's armamentarium in the treatment of motor fluctuations. Sublingual apomorphine is the first sublingual rescue medication on the market for the treatment of OFF times in PD.Materials and Methods: Here, we review the development and pharmacology of apomorphine in the treatment of PD as well as the safety and efficacy of sublingual apomorphine established in clinical trials. Finally, we compare sublingual apomorphine to the other rescue medications available and provide our opinion on the use of sublingual apomorphine in clinical practice.Results: Clinical trials have demonstrated that sublingual apomorphine is a safe and effective option in the treatment of motor fluctuations in PD. In a Phase II trial, 100% of patients who achieved a full ON response did so within 30 min and 40% did so within 15 min. The mean duration of effect was 50 min. In a Phase III trial, 77.3% of patients achieved a full ON response. Side effects such as nausea, dizziness and somnolence were common but were generally mild. No patients experienced worsening dyskinesia.Conclusions: Sublingual apomorphine will provide patients with motor fluctuations due to advanced PD another safe and effective option for the treatment of OFF times.

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.

Intrinsic auricular muscle zone stimulation for Parkinson disease: The EARSTIM-PD Phase II multi-center pilot study results

BACKGROUND

Studies have suggested that intrinsic auricular muscle zones (IAMZ) stimulation alleviates motor features of Parkinson disease (PD).

METHODS

A randomized, blinded, active sham-controlled pilot trial was conducted to evaluate the safety and dose-response-time curve of Earstim using a 3-treatment, 3-period crossover design in PD patients experiencing OFF time on levodopa. Treatments were: short (20-min) IAMZ stimulation; long (60-min) IAMZ stimulation; and 20-min active sham stimulation of non-muscular areas. Assessment time points were: prior to treatment, and 20, 40, 60, 90, and 120 min after treatment onset. Primary safety endpoints were adverse events frequency and severity. Primary efficacy endpoint was the change in MDS-UPDRS motor score at 20 min after treatment onset in the IAMZ treatment groups versus sham.

RESULTS

Forty-six individuals consented; 38 were randomized (average age 64 years, 65 % male, mean 8.2 years from diagnosis). No serious adverse events or significant device-related events occurred. At 20 min after treatment onset, motor improvements did not differ between IAMZ treatments versus sham. However, at 60 min after treatment onset, motor improvement peaked on IAMZ treatments compared to sham (difference: 3.1 [-5.9 to 0.3], p = 0.03). While the difference in 120-min AUC change between IAMZ treatments versus sham was not significant, the short-stimulation IAMZ treatment showed the largest aggregate motor score improvement (AUC = -456 points, 95 % CI -691 to -221) compared to sham.

CONCLUSION

Earstim was well-tolerated. The greatest motor improvement occurred at 60 min after stimulation onset in the short-stimulation IAMZ treatment, and supports its further study to alleviate OFF periods.

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.

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

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

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.

Drugs to the Rescue: Comparison of On-Demand Therapies for OFF Symptoms in Parkinson's Disease

Patients with Parkinson's disease often suffer from OFF symptoms disrupting their daily routines and adding to disabilities. Despite polypharmacy and adjustments to medication schedules, they often do not experience consistent relief from their motor symptoms. As the disease progresses, impaired gastric emptying may evolve, making it even more challenging for dopaminergic drugs to provide consistent results. This review focuses on a group of drugs that have the pharmacokinetic advantage of a much earlier onset of action by virtue of their non-oral routes of absorption. We compare the current marketed options: subcutaneous apomorphine, sublingual apomorphine, and inhaled levodopa. Subcutaneous apomorphine is the speediest to take effect, whereas sublingual apomorphine offers the longest clinical effect. Inhaled levodopa has the most favorable side effect profile among the three options. An inhaled form of apomorphine is currently under development, having passed safety and efficacy studies. Each of these drugs has unique characteristics for the user, including different side effect profiles and onset of action. The best choice for a patient will depend on individual needs and circumstances. In this review, we explore those nuances to allow clinicians to select the best option for their patients.

The Clinical Development of Levodopa Inhalation Powder

ABSTRACT

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

Off-time Treatment Options for Parkinson's Disease

Motor fluctuations (MF) are deemed by patients with Parkinson's disease (PD) as the most troublesome disease feature resulting from the increasing impairment in responsiveness to dopaminergic drug treatments. MF are characterized by the loss of a stable response to levodopa over the nychthemeron with the reappearance of motor (and non-motor) parkinsonian clinical signs at various moments during the day and night. They normally appear after a few years of levodopa treatment and with a variable, though overall increasing severity, over the disease course. The armamentarium of first-line treatment options has widened in the last decade with new once-a-daily compounds, including a catechol O-methyltransferase inhibitor - Opicapone-, two MAO-B inhibitors plus channel blocker - Zonisamide and Safinamide and one amantadine extended-release formulation - ADS5012. In addition to apomorphine injection or oral levodopa dispersible tablets, which have been available for a long time, new on-demand therapies such as apomorphine sublingual or levodopa inhaled formulations have recently shown efficacy as rescue therapies for Off-time treatment. When the management of MF becomes difficult in spite of oral/on-demand options, more complex therapies should be considered, including surgical, i.e. deep brain stimulation, or device-aided therapies with pump systems delivering continuous subcutaneous or intestinal levodopa or subcutaneous apomorphine formulation. Older and less commonly used ablative techniques (radiofrequency pallidotomy) may also be effective while there is still scarce data regarding Off-time reduction using a new lesional approach, i.e. magnetic resonance-guided focused ultrasound. The choice between the different advanced therapies options is a shared decision that should consider physician opinion on contraindication/main target symptom, patients' preference, caregiver's availability together with public health systems and socio-economic environment. The choice of the right/first add-on treatment is still a matter of debate as well as the proper time for an advanced therapy to be considered. In this narrative review, we discuss all the above cited aspects of MF in patients with PD, including their phenomenology, management, by means of pharmacological and advanced therapies, on-going clinical trials and future research and treatment perspectives.

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.

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

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

Recent advances in drug delivery to the central nervous system by inhalation

INTRODUCTION

Drugs need to enter the systemic circulation efficiently before they can cross the blood-brain barrier and reach the central nervous system. Although the respiratory tract is not a common route of administration for delivering drugs to the central nervous system, it has attracted increasing interest in recent years for this purpose.

AREAS COVERED

In this article, we compare pulmonary delivery to three other common routes (parenteral, oral, and intranasal) for delivering drugs to the central nervous system, followed by summarising the devices used to aerosolise neurological drugs. Recent studies delivering drugs for different neurological disorders via inhalation are then discussed to illustrate the strengths of pulmonary delivery.

EXPERT OPINION

Recent studies provide strong evidence and rationale to support inhaling neurological drugs. Since inhalation can achieve improved pharmacokinetics and rapid onset of action for multiple drugs, it is a non-invasive and efficient method to deliver drugs to the central nervous system. Future research should focus on delivering other small and macro-molecules via the lungs for different neurological conditions.

Safety and pharmacokinetics of multiple dosing with inhalable apomorphine (AZ-009), and its efficacy in a randomized crossover study in Parkinson's disease patients

INTRODUCTION

Apomorphine is used to treat OFF periods in Parkinson's disease (PD) patients. AZ-009 is a novel apomorphine formulation that delivers a thermally-generated aerosol to the deep lung via inhalation with a single breath.

METHODS

Part A was a randomized, placebo-controlled, double-blind study investigating the safety and pharmacokinetics of multiple ascending doses of AZ-009. PD patients (n = 24) received placebo or 2, 3 or 4 mg AZ-009 once daily for 5 days, followed by three times daily for 2 days with 2 h between doses. Part B was a double-blind crossover study in 8 PD patients who experience OFF periods. During an OFF state, patients received 4 mg AZ-009 and placebo on two consecutive days in a randomized order. MDS-UPDRS III and ON/OFF state were assessed pre- and post-dose.

RESULTS

Three times daily dosing with 2, 3 and 4 mg AZ-009 was relatively well tolerated with no apparent accumulation or changes in safety profile. Mild and transient throat irritation and cough were reported most often. AZ-009 was rapidly absorbed with median T_max between 1 and 2 min. When corrected for placebo response, the maximum effect of 4 mg AZ-009 based on MDS-UPDRS III scores was observed at 10 and 30 min post-dose with mean (SD) reductions of 6.8 (9.4) and 6.1 (9.1) points respectively. Whereas 0% of patients turned ON after placebo, 50% turned ON 10 min after 4 mg AZ-009 treatment.

CONCLUSION

AZ-009 is rapidly systemically absorbed and safe to dose three times daily. AZ-009 could provide a faster-acting and easier to use formulation than currently available therapies.

Inhaled Levodopa (CVT-301) for the Treatment of Parkinson Disease: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Purpose

of Review: To investigate the efficacy and safety of CVT-301 for motor fluctuation in Parkinson’s disease (PD).

Recent Findings:

This study demonstrated that the CVT-301 group had a higher proportion of patients achieving an ON state than the placebo group (OR=2.68; 95% CI: 1.86-3.86; p<0.00001). Moreover, CVT-301 had also shown to improve motor function by UPDRS-III score (SMD=3.83; 95% CI: 2.44-5.23; p<0.00001) and promote an overall improvement of PD by PGIC self-rating (OR=2.95; 95% CI: 1.78-4.9; p<0.00001). The most common adverse events encountered were respiratory symptoms (OR=12.18; 95% CI: 5.01-29.62; p<0.00001) and nausea (OR=3.95; 95% CI: 1.01-15.41; p=0.05).

Summary:

CVT-301 had the potential to be an alternative or even a preferred treatment for motor fluctuation in PD patients.

Parkinson Disease: Translating Insights from Molecular Mechanisms to Neuroprotection

Parkinson disease (PD) used to be considered a nongenetic condition. However, the identification of several autosomal dominant and recessive mutations linked to monogenic PD has changed this view. Clinically manifest PD is then thought to occur through a complex interplay between genetic mutations, many of which have incomplete penetrance, and environmental factors, both neuroprotective and increasing susceptibility, which variably interact to reach a threshold over which PD becomes clinically manifested. Functional studies of PD gene products have identified many cellular and molecular pathways, providing crucial insights into the nature and causes of PD. PD originates from multiple causes and a range of pathogenic processes at play, ultimately culminating in nigral dopaminergic loss and motor dysfunction. An in-depth understanding of these complex and possibly convergent pathways will pave the way for therapeutic approaches to alleviate the disease symptoms and neuroprotective strategies to prevent disease manifestations. This review is aimed at providing a comprehensive understanding of advances made in PD research based on leveraging genetic insights into the pathogenesis of PD. It further discusses novel perspectives to facilitate identification of critical molecular pathways that are central to neurodegeneration that hold the potential to develop neuroprotective and/or neurorestorative therapeutic strategies for PD. SIGNIFICANCE STATEMENT: A comprehensive review of PD pathophysiology is provided on the complex interplay of genetic and environmental factors and biologic processes that contribute to PD pathogenesis. This knowledge identifies new targets that could be leveraged into disease-modifying therapies to prevent or slow neurodegeneration in PD.

Engineering of levodopa inhalable microparticles in combination with leucine and dipalmitoylphosphatidylcholine by spray drying technique

The aim of this work was to study the effect of concomitant use of leucine and dipalmitoylphosphatidylcholine, in different ratios, on aerosolization performance of levodopa. Three-component formulations were selected based on a central composite design using percentages of leucine and dipalmitoylphosphatidylcholine as the independent variables. Particle size, surface roughness index, surface phosphorus and fine particle fraction were considered as dependent variables in the model. The spray dried samples were also characterized to determine their particle shape and solid state nature. levodopa was spray dried with 10-40% w/w of the excipients to prepare two- or three-component formulations. A crystalline nature was determined for levodopa in all samples spray dried from water:ethanol (30:70 v/v). Roughness in surface of the processed particles increased with increasing total concentration of the excipients, specially above 25% w/w. Analysis of phosphorus on the surface demonstrated that three-component formulations prepared with combination of 12.5% w/w leucine had the highest amount of dipalmitoylphosphatidylcholine in the surface, regardless of its percentage used in the initial feed. A combination of 12.43% w/w of leucine and 9.80% w/w of dipalmitoylphosphatidylcholine used in formulation exhibited the highest fine particle fraction (72.63%). It can be concluded that spray drying of levodopa with a suitable combination of both excipients leads to production of a three-component formulation of crystalline levodopa, with an aerosolization performance which is significantly higher than two-component formulations composed of the drug with either leucine or dipalmitoylphosphatidylcholine.

A technology evaluation of CVT-301 (Inbrija): an inhalable therapy for treatment of Parkinson's disease

Introduction: The most widely used pharmacological treatment for Parkinson's disease is levodopa, the precursor for dopamine formation in the brain. Over time, the effectiveness of levodopa declines, and patients experience motor fluctuations, or OFF periods. A levodopa formulation administered via a capsule-based oral inhaler provides a new delivery mechanism for levodopa that provides rapid relief of OFF periods.Areas covered: CVT-301 is a dry powder formulation designed to supply levodopa to the systemic circulation via pulmonary absorption. The technology, pharmacokinetics, efficacy, and safety data of this formulation are presented.Expert opinion: Oral inhalation is a novel method of administration for levodopa that bypasses the gastrointestinal tract, allowing levodopa to enter the systemic circulation rapidly and more reliably than oral medications. Gastrointestinal dysfunction, a common feature of Parkinson's disease, can lead to impaired absorption of oral medications. Pulmonary delivery rapidly elevates levodopa plasma concentrations to provide relief of OFF periods for patients receiving oral levodopa.

On-Demand Therapy for OFF Episodes in Parkinson's Disease

Levodopa is the most effective therapy for Parkinson's disease; however, chronic treatment is associated with the development of OFF episodes, in which there is a return of parkinsonian features following a dose of levodopa and prior to the onset of benefit from the subsequent dose. OFF episodes can be a major source of disability for PD patients and frequently result in depression, apathy and an unwillingness to participate in social activities. Most currently available medical and surgical therapies are designed to reduce total daily OFF time but do not provide a rapid and reliable "on-demand" therapy for individual OFF episodes. Indeed, responses to individual doses of levodopa during an acute OFF episode are unreliable, frequently leading to partial-ON, delayed-ON, or no-ON responses even at different times in the same patient. There are now 3 therapies that are available for the on-demand treatment of OFF episodes; subcutaneous injection of apomorphine, sublingual apomorphine film, and inhaled levodopa. The first has not enjoyed widespread use in the PD community, whereas the latter 2 therapies have only recently been approved. This review will consider the currently available on-demand therapies and their potential advantages and disadvantages. © 2021 International Parkinson and Movement Disorder Society.

Emerging Pharmacotherapies for Motor Symptoms in Parkinson's Disease

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

On demand therapy for Parkinson's disease patients: Opportunities and choices

Levodopa is the most effective symptomatic treatment for Parkinson's disease (PD), but a major treatment challenge is that over time, many patients experience periods of return of PD symptoms intermittently through the day, known as OFF periods. OFF periods typically manifest as a return of motor symptoms but can also involve non-motor symptoms and these periods can disrupt good control despite optimization of the oral levodopa regimen. OFF periods emerge in large measure due to a shortening of the duration of clinical benefit from oral levodopa, thought to be related to a progressive loss of dopamine neurons and their ability to store and release levodopa-derived dopamine over many hours. The problem is further compounded by impaired absorption of oral levodopa due to gastroparesis and other factors limiting its uptake in the small intestine, including competition for uptake by meals and their protein content. On-demand therapies are now available for the treatment of OFF episodes in PD and are administered intermittently, on an as-needed basis, on top of the patient's maintenance medication regimen. To be useful, an on-demand medication should take effect more rapidly and reliably than oral levodopa. Options for on-demand therapy for OFF periods have recently increased with the approval of levodopa inhalation powder and sublingual apomorphine as alternatives to the older option of subcutaneous apomorphine injection, each of which avoids the gastrointestinal tract and its potential for absorption delay. On-demand therapy is now available for patients experiencing episodic or intermittent need for rapid and reliable onset of benefit. On-demand therapy may also provide an alternative to more invasive treatment such as infusion of levodopa/carbidopa intestinal gel and for patients whose OFF episodes are not controlled despite deep brain stimulation.

An evaluation of the efficacy and value of CVT-301 for the treatment of Parkinson's disease

Introduction: Levodopa is the most effective drug in the treatment of Parkinson's disease, but its chronic treatment is linked to the occurrence of motor complications with fluctuations of motor performance and dyskinesia. Unpredictable OFF episodes can be severe and disabling and current rescue medications cannot always be used safely. Rescue therapy is characterized by a rapid and predictable ON response and the safety profile of levodopa will represent a major advantage for patients affected by unresponsive OFF episodes.Areas covered: CVT-301 is a new inhaled formulation of LD recently developed as a self-administered treatment for OFF periods. Herein, the pharmacodynamic and pharmacokinetic properties, efficacy, and safety of CVT-301 are reviewed.Expert opinion: CVT-301 may offer several potential advantages including increased systemic bioavailability through pulmonary absorption, rapid onset of action, avoidance of first-pass drug metabolism, and less plasma level variability. It should be noted that the delivery device used has been described as relatively simple to use, but the few steps required to prepare and self-administer the dose can be challenging for PD patients during their OFF state. Additionally, resolution of an OFF episode requires the administration of two capsules of CVT-301, which further complicates the use of the device.

Research on developing drugs for Parkinson's disease

Current treatments for Parkinson's disease (PD) are mainly dopaminergic drugs. However, dopaminergic drugs are only symptomatic treatments and limited by several side effects. Recent studies into drug development focused on emerging new molecular mechanisms, including nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, nuclear receptor-related 1 (Nurr1), adenosine receptor A2, nicotine receptor, metabotropic glutamate receptors (mGluRs), and glucocerebrosidase (GCase). Also, immunotherapy and common pathological mechanisms shared with Alzheimer's Disease (AD) and diabetes have attracted much attention. In this review, we summarized the development of preclinical and clinical studies of novel drugs and the improvement of dopaminergic drugs to provide a prospect for PD treatment.

Levodopa Inhalation Powder: A Review in Parkinson's Disease

Levodopa inhalation powder (Inbrija^®) is approved for the intermittent treatment of OFF episodes in patients with Parkinson's disease (PD) treated with levodopa/dopa-decarboxylase inhibitor (LD-DCI) in the EU and specifically with carbidopa/levodopa in the USA. The approved dosage is 84 mg taken as needed up to five times a day. Administered via a breath-actuated inhaler, this formulation enables levodopa to bypass the gastrointestinal (GI) tract and, instead, rapidly enter the bloodstream through the pulmonary system. In the 12-week, double-blind, placebo-controlled, phase III SPAN-PD trial, as-needed levodopa inhalation powder 84 mg improved motor symptoms during OFF periods in PD patients (aged 30-86 years) treated with levodopa and carbidopa or benserazide. The likelihood of achieving an ON state 60 min postdose was significantly higher in the levodopa inhalation powder than the placebo group, with most patients in the levodopa inhalation powder group experiencing improvements in PD symptoms. Findings from longer-term, 52-week phase III studies were consistent with those from the SPAN-PD trial with regards to the treatment of OFF episodes. Levodopa inhalation powder was generally well tolerated and did not noticeably affect pulmonary function in PD patients. Providing a nonintrusive, convenient treatment method, levodopa inhalation powder is a promising option for the intermittent treatment of OFF episodes in patients with PD treated with a LD-DCI.

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.

Chitosan-Coated Hydroxypropylmethyl Cellulose Microparticles of Levodopa (and Carbidopa): In Vitro and Rat Model Kinetic Characteristics

Background

Parkinson's disease is a neurodegenerative disorder, and a major cause of disability. Levodopa, a prodrug of dopamine, remains the gold standard in the pharmacological management of Parkinson's disease. Despite several attempts to improve the clinical efficacy of levodopa, new oral levodopa formulations are needed to overcome irregular absorption and variable plasma concentrations.

Objective

The aim of this study was to evaluate the in vitro and in vivo kinetic properties of chitosan-coated hydroxypropylmethyl cellulose microparticles of levodopa (and carbidopa).

Methods

Microparticles were formulated by encapsulating levodopa powder in chitosan-coated hydroxypropylmethyl cellulose using the spray-drying method. Levodopa microparticles were evaluated for size, zeta potential, drug loading capacity, encapsulation efficiency and in vitro release. In evaluating in vivo pharmacokinetics, Sprague Dawley rats were administered either levodopa/carbidopa powder, levodopa/carbidopa microparticles, or Sinemet CR (a controlled release formulation of levodopa/carbidopa). The dose of respective formulations administered was 20/5 mg/kg; 20 mg levodopa combined with 5 mg carbidopa per kilogram body weight of animals. Treatments were administered via the oral route every 12 hours. Blood samples were collected after predetermined times following the third dose. Plasma was obtained from blood collected, and levodopa levels determined by HPLC. Pharmacokinetic parameters, including C_max, T_max, AUC, and t_½ of the various formulations, were estimated.

Results

The mean (SD) size of levodopa microparticles was 0.5 (0.05) µm with polydispersity index of 0.41 and a zeta potential of 10.8 mV. Of the expected 20% drug loading, the actual drug loading capacity of levodopa microparticles was found to be 19.1%, giving an encapsulation efficiency of 95.7%. The in vitro release kinetics of levodopa microparticles showed a controlled and sustained release, with about 80% release occurring after 12 hours. In vivo pharmacokinetic studies showed that rats administered levodopa/carbidopa microparticles had greater AUC (612.7 [17.42] ng.h/mL) and higher C_max (262.4 [38.86] ng/mL) compared with Sinemet CR: AUC 354.7 (98.09) ng.h/mL and C_max 95.5 (20.87) ng/mL. However, Sinemet CR had a much longer half-life (6.1 [2.58] hours) compared with levodopa/carbidopa microparticles (2.0 [0.31] hours).

Conclusions

Findings from this study suggest that chitosan-coated hydroxypropylmethyl cellulose microparticles of levodopa/carbidopa may give relatively high levels of levodopa in circulation. (Curr Ther Res Clin Exp. 2020; 81:XXX–XXX)

© 2020 Elsevier HS Journals, Inc.

Medical Management and Prevention of Motor Complications in Parkinson's Disease

Levodopa is the most effective medication for the treatment of the motor symptoms of Parkinson's disease. However, over time, the clinical response to levodopa becomes complicated by a reduction in the duration and reliability of motor improvement (motor fluctuations) and the emergence of involuntary movements (levodopa-induced dyskinesia). Strategies that have been attempted in an effort to delay the development of these motor complications include levodopa sparing and continuous dopaminergic therapy. Once motor complications occur, a wide array of medical treatments is available to maximize motor function through the day while limiting dyskinesia. Here, we review the clinical features, epidemiology, and risk factors for the development of motor complications, as well as strategies for their prevention and medical management.

Adaptive Eating Device: Performance and Satisfaction of a Person with Parkinson's Disease

BACKGROUND.

Individuals with Parkinson's disease (PD) can experience motor impairments related to their hand-use that restrict participation in daily activities. Feeding is one activity impacted by this health condition. The use of adapted utensils can improve performance and independence in this activity.

PURPOSE.

To investigate if a locally designed and made eating-adaptive device helps a person with PD to improve their feeding performance.

METHOD.

Single-case ABC-type experimental design. Performance and satisfaction of a 60-year-old man with PD were assessed during feeding tasks in 70 sequential days in three phases. Celeration Line, Two-Standard Deviation Band, and Visual Analysis were the methods used for data analysis.

FINDINGS.

Performance and satisfaction increased significantly after the introduction of the adaptive eating device. The addition of weight also contributed to the increase in the participant's performance.

IMPLICATIONS.

Adaptive eating device with low production costs and possibility of customized adjustments improves performance of people with PD.

Clinical implications of gastric complications on levodopa treatment in Parkinson's disease

Disorders of the gastrointestinal (GI) tract are common and distressing nonmotor symptoms of Parkinson's disease (PD) that can adversely affect levodopa absorption and lead to OFF periods, also known as motor fluctuations. Gastroparesis, which is primarily defined as delayed gastric emptying (DGE), and Helicobacter pylori infection, which is present with increased frequency in PD, are among the most common and important GI disorders reported in PD that may impair oral levodopa absorption and increase OFF time. Symptoms of gastroparesis include nausea, vomiting, postprandial bloating, fullness, early satiety, abdominal pain, and weight loss. DGE has been reported in a substantial fraction of individuals with PD. Symptoms of H. pylori infection include gastritis and peptic ulcers. Studies have found that DGE and H. pylori infection are correlated with delayed peak levodopa plasma levels and increased incidence of motor fluctuations. Therapeutic strategies devised to minimize the potential that gastric complications will impair oral levodopa absorption and efficacy in PD patients include treatments that circumvent the GI tract, such as apomorphine injection, levodopa intestinal gel delivery, levodopa inhalation powder, and deep brain stimulation. Other strategies aim at improving gastric emptying in PD patients, primarily including prokinetic agents.

Current Therapeutic Strategies and Perspectives for Neuroprotection in Parkinson's Disease

Parkinson's disease is a progressive neurodegenerative disorder of dopaminergic striatal neurons in basal ganglia. Treatment of Parkinson's disease (PD) through dopamine replacement strategies may provide improvement in early stages and this treatment response is related to dopaminergic neuronal mass which decreases in advanced stages. This treatment failure was revealed by many studies and levodopa treatment became ineffective or toxic in chronic stages of PD. Early diagnosis and neuroprotective agents may be a suitable approach for the treatment of PD. The essentials required for early diagnosis are biomarkers. Characterising the striatal neurons, understanding the status of dopaminergic pathways in different PD stages may reveal the effects of the drugs used in the treatment. This review updates on characterisation of striatal neurons, electrophysiology of dopaminergic pathways in PD, biomarkers of PD, approaches for success of neuroprotective agents in clinical trials. The literature was collected from the articles in database of PubMed, MedLine and other available literature resources.

Inhaled levodopa for intermittent treatment of OFF episodes in patients with Parkinson's disease

Introduction: Many patients with advanced Parkinson's disease (PD) have inadequate control of motor symptoms despite optimized treatment. Predictable and unpredictable OFF periods severely interfere with the quality of life. A drug that easily and rapidly reverts the OFF state is still needed. Subcutaneous apomorphine, the only approved drug for this indication, although efficacious, is not widely used probably due to its potential side effects and complicated administration.Levodopa is the most efficacious drug for the treatment of PD motor symptoms. However, issues related to the oral route and intestinal absorption in later disease stages render this route lengthy and inefficacious.Areas covered: Literature on the development of an inhaled formulation of levodopa has been reviewed. Significant advances in the field of pulmonary delivery systems and in dry powders have enabled the development of a new formulation of levodopa that can be inhaled and adequate blood levels rapidly achieved, bypassing intestinal absorption. Several clinical trials have reported efficacy, safety, and tolerability data. Some pulmonary-related adverse events have been reported but are mostly mild.Expert opinion: This new way of administering levodopa is likely to be very welcome and may fill a gap for OFF rescue treatments, at least for some patients.

Inhaled levodopa in Parkinson's disease patients with OFF periods: A randomized 12-month pulmonary safety study

INTRODUCTION

CVT-301 is an orally inhaled levodopa therapy approved for the intermittent treatment of OFF episodes in Parkinson's disease patients who are taking a standard oral levodopa regimen. This open-label, randomized, controlled study over 12 months characterizes the safety, including pulmonary safety, of CVT-301 84 mg (nominal respirable levodopa fine-particle dose, 50 mg).

METHODS

Patients experiencing motor fluctuations were randomized 2:1 to CVT-301 or an observational cohort (OC) receiving oral standard of care. Pulmonary safety was assessed using spirometry and carbon monoxide diffusion capacity (DL_CO). Exploratory efficacy endpoints, assessed only for CVT-301, included change in Unified Parkinson's Disease Rating Scale Part III (UPDRS-III), patients achieving ON within 60 min and remaining ON at 60 min, Patient Global Impression of Change (PGIC) scale, and total daily OFF time.

RESULTS

Of 408 patients randomized, 310 completed the study (204 in CVT-301 and 106 in OC). Mean 12-month changes from baseline for CVT-301 were -0.105 L (FEV₁) and -0.378 mL/min/mm Hg (DL_CO), and for OC were -0.117 L and -0.722 mL/min/mm Hg, respectively. Between-group comparisons were not statistically significant. For FEV₁/FVC the 12-month change was -0.3 and -1.6, respectively, which was a significant between-group difference. However, between-group differences were not significant at 3 and 9 months and all changes from baseline were small (<2.0%). UPDRS-III scores improved from predose to 60 min postdose at all assessments; 80%-85% of patients switched ON within 60 min and remained ON; and >75% reported improvement in PGIC. OFF time decreased by 1.32-1.42 h/day.

CONCLUSION

CVT-301 84 mg induced no clinically significant differences in pulmonary function compared with the OC. Improvements in motor scores, OFF time, and patient-reported outcomes support clinical efficacy for up to 12 months.

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.

Progress of Pharmacological Approaches in Parkinson's Disease

The progressive neurodegenerative process in Parkinson's disease (PD) is not restricted to dopaminergic midbrain neurons but involves the entire nervous system. In this review, we outline established treatment options at different disease stages and address new therapeutic approaches. These include, based on recent advances in the understanding of the pathophysiology of PD, genetic and disease-modifying approaches to reduce abnormal accumulation and aggregation of alpha-synuclein (aSYN), mitochondrial dysfunction, and dysfunction of lysosomal proteins. Moreover, we highlight clinical trials to reduce neuroinflammation and increase neurorestoration.

Update in therapeutic strategies for Parkinson's disease

PURPOSE OF REVIEW

To review recent advances in therapeutics for motor and nonmotor symptoms of Parkinson's disease.

RECENT FINDINGS

Neuroprotection remains a large area of investigation with preliminary safety data on alpha synuclein immunotherapy and glucagon-like peptide-1 agonists. Novel Monoamine Oxidase B and Caetchol-O-methyltransferase-inhibitors for motor fluctuations have shown benefit and are recently approved for clinical use. Long-acting amantadine has also been approved to reduce dyskinesia. Alternative delivery strategies (sublingual, inhaled) dopaminergics may prove useful for rapid reversal of Parkinson's disease motor symptoms. Advanced therapies (surgery and infusional therapies) continue to be useful in subgroups of patients for motor complications with improved safety and also benefit on some nonmotor symptoms, including neuropsychiatric issues. Specific therapeutics for cognition, swallowing, sleep, and mood disorders had moderate to limited benefits. Exercise-based therapy appears beneficial at all stages of Parkinson's disease.

SUMMARY

The motor symptoms of Parkinson's disease can be reasonably treated and managed. However, therapies to slow or prevent disease progression remain a focus of research. Despite increased studies, treating nonmotor symptoms remains a challenge and an ongoing priority.

Can the Latest Computerized Technologies Revolutionize Conventional Assessment Tools and Therapies for a Neurological Disease? The Example of Parkinson's Disease

Dramatic breakthroughs in the treatment and assessment of neurological diseases are lacking. We believe that conventional methods have several limitations. Computerized technologies, including virtual reality, augmented reality, and robot assistant systems, are advancing at a rapid pace. In this study, we used Parkinson's disease (PD) as an example to elucidate how the latest computerized technologies can improve the diagnosis and treatment of neurological diseases. Dopaminergic medication and deep brain stimulation remain the most effective interventions for treating PD. Subjective scales, such as the Unified Parkinson's Disease Rating Scale and the Hoehn and Yahr stage, are still the most widely used assessments. Wearable sensors, virtual reality, augmented reality, and robot assistant systems are increasingly being used for evaluation of patients with PD. The use of such computerized technologies can result in safe, objective, real-time behavioral assessments. Our experiences and understanding of PD have led us to believe that such technologies can provide real-time assessment, which will revolutionize the traditional assessment and treatment of PD. New technologies are desired that can revolutionize PD treatment and facilitate real-time adjustment of treatment based on motor fluctuations, such as telediagnosis systems and "smart treatment systems." The use of these technologies will substantially improve both the assessment and the treatment of neurological diseases before next-generation treatments, such as stem cell and genetic therapy, and next-generation assessments, can be clinically practiced, although the current level of artificial intelligence cannot replace the role of clinicians.

Challenges for pulmonary delivery of high powder doses

In recent years there is an increasing interest in the pulmonary delivery of large cohesive powder doses, i.e. drugs with a low potency such as antibiotics or drugs with a high potency that need a substantial fraction of excipient(s) such as vaccines stabilized in sugar glasses. The pulmonary delivery of high powder doses comes with unique challenges. For low potency drugs, the use of excipients should be minimized to limit the powder mass to be inhaled as much as possible. To achieve this objective the inhaler design should be adapted to the properties of the API in order to achieve a compatible combination of the drug formulation and inhaler device. The inhaler should have an appropriate powder dosing principle for which prefilled compartments seem most appropriate. The drug formulation should not only allow for accurate filling of these compartments but also enable efficient compartment emptying during inhalation. The dispersion principle must have the capacity to disperse considerable amounts of powder in a short time frame that allows the powder to reach the deep lung. Last, but not least, the inhaler should be simple and intuitive in use, be cost-effective and exhibit accurate and consistent, preferably patient independent, pulmonary delivery performance.

Safinamide: an add-on treatment for managing Parkinson's disease

Heterogeneous expression of neurotransmitter deficits results from onset and progression of Parkinson's disease. Intervals, characterized by reappearance of motor and associated certain nonmotor symptoms, determine the end of good tolerability and efficacy of oral levodopa therapy. These "OFF" states result from levodopa pharmacokinetics and disease progression-related deterioration of the central buffering capacity for fluctuations of dopamine levels. This review discusses safinamide as an add-on therapeutic agent in orally levodopa-treated patients with "OFF" phenomena. Safinamide provided beneficial effects on "OFF" symptoms in pivotal trials with doses of 50 or 100 mg once daily. Safinamide reversibly inhibits mono-amine oxidase B and declines abnormal glutamate release by modulation of potassium- and sodium ion channels. An ideal candidate for combination with safinamide is opicapone. This inhibitor of peripheral catechol-O-methyltransferase supports continuous brain delivery of levodopa and, thus, the continuous dopaminergic stimulation concept. Both compounds with their once-daily application and good tolerability may complement each other by reduction of necessary oral levodopa intakes and "OFF" times. Thus, a promising, future option will be combination of safinamide and opicapone in one formulation. It will reduce adherence issues and may complement levodopa treatment. It will probably cause less nausea and edema than a dopamine agonist/levodopa regimen.