Deprenyl in the treatment of symptom fluctuations in advanced Parkinson's disease

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

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

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Monoamine Oxidase-B Inhibitors for the Treatment of Parkinson's Disease: Past, Present, and Future

Monoamine oxidase-B (MAO-B) inhibitors are commonly used for the symptomatic treatment of Parkinson’s disease (PD). MAO-B inhibitor monotherapy has been shown to be effective and safe for the treatment of early-stage PD, while MAO-B inhibitors as adjuvant drugs have been widely applied for the treatment of the advanced stages of the illness. MAO-B inhibitors can effectively improve patients’ motor and non-motor symptoms, reduce “OFF” time, and may potentially prevent/delay disease progression. In this review, we discuss the effects of MAO-B inhibitors on motor and non-motor symptoms in PD patients, their mechanism of action, and the future development of MAO-B inhibitor therapy.

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.

From medications to surgery: advances in the treatment of motor complications in Parkinson's disease

Motor complications are responsible for the large burden of disability and poor quality of life in Parkinson’s disease (PD). The pulsatile nature of stimulation with oral dopaminergic therapies due to relatively short pharmacokinetic profiles and dysfunctional gastrointestinal absorption have been attributed to the development of PD motor complications. In this review, we will provide an overview of the pharmacologic and surgical therapies currently available and under investigation for the treatment of motor fluctuations and dyskinesia.

Selegiline increases on time without exacerbation of dyskinesia in 6-hydroxydopamine-lesioned rats displaying l-Dopa-induced wearing-off and abnormal involuntary movements

3,4-Dihydroxy-l-phenylalanine (l-Dopa) remains the most effective drug for treating the motor symptoms of Parkinson's disease (PD). However, its long-term use is limited due to motor complications such as wearing-off and dyskinesia. A clinical study in PD patients with motor complications has demonstrated that selegiline, a monoamine oxidase type B inhibitor, is effective in reducing off time without worsening dyskinesia, although another study has shown worsening dyskinesia. Here, using unilateral 6-hydroxydopamine-lesioned rats showing degeneration of nigrostriatal dopaminergic neurons and l-Dopa-induced motor complications, we determined the efficacy of selegiline in controlling l-Dopa-induced motor fluctuations and exacerbated dyskinesia. Repeated administration of l-Dopa/benserazide (25/6.25 mg/kg, intraperitoneally, twice daily for 22 days) progressively shortened rotational response duration (on time) and augmented peak rotation in lesioned rats. Single subcutaneous injection of selegiline (10 mg/kg) extended l-Dopa-induced shortened on time without augmenting peak rotation. Furthermore, l-Dopa/benserazide (25/6.25 mg/kg, intraperitoneally, once daily for 7 days) progressively increased abnormal involuntary movements (l-Dopa-induced dyskinesia, LID) and peak rotation. Single subcutaneous injection of selegiline (10 mg/kg) did not exacerbate LID or alter mRNA expression of prodynorphin (PDy) and activity-regulated cytoskeleton-associated protein (Arc), both mRNAs associated with LID in the lesioned striatum. Despite undetectable plasma concentrations of selegiline and its metabolites at 24 h post-administration, these on time and LID effects did not decrease, suggesting involvement of irreversible mechanisms. Altogether, these results indicate that selegiline is effective in increasing on time without worsening dyskinesia.

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.

Deprenyl in Parkinson’s Disease: Mechanisms, Neuroprotective Effect, Indications and Adverse Effects

Deprenyl is a synthetic, selective inhibitor of the monoamine oxidase-B enzyme system. The mechanism of its beneficial effect in early and advanced Parkinson’s disease is not settled. Increased striatal dopamine accumulation, sensitization of surviving dopamine neurons with increased dopamine production and reduced nigro-striatal toxicity may all contribute. The standard daily dose of deprenyl is 10 mg. Selectivity may be lost at higher doses. Deprenyl is especially indicated in untreated patients, improving up to 50 percent of patients with mild motor fluctuations. Major symptomatic benefit also occurs in occasional levodopa treated patients. Adverse effects are common, however. Increase dyskinesias, confusion and hallucinations, nausea and postural hypotension may necessitate drug withdrawal or the use of low dose regimens. Caution should be exercised with older patients, those with ulcer disease, which may be worsened by deprenyl, and individuals with active ischemic heart disease where the safety of this drug is not yet clear.

Improving L-dopa therapy: the development of enzyme inhibitors

The introduction of levodopa produced a monumental change in the treatment of Parkinson's disease (PD). Limitations in its bioavailability and tolerability led to the search for drugs that could improve its pharmacokinetics and safety profile. Dopa-decarboxylase inhibitors were the first such drugs that were developed, and their use in combination with L-dopa has become standard practice. Increasing knowledge on the metabolism of L-dopa allowed the identification of additional targets for intervention in an attempt to improve the symptomatic efficacy of L-dopa. Monoamineoxidase inhibitors, enhancing the central bioavailability of dopamine by blocking its metabolism, were the next step, and despite controversies regarding their efficacy, they have remained as valuable adjuncts to l-dopa in the treatment of PD. More recently, the introduction of potent, selective catechol-O-methyl transferase inhibitors have found their place in the therapeutic armamentarium of PD and are prescribed in combination with l-dopa to prolong the duration of its action.

Recent advances in Parkinson’s disease therapy: use of monoamine oxidase inhibitors

Monoamine oxidase inhibitors inhibit dopamine metabolism and are therefore effective in treating Parkinson's disease, a condition associated with progressive striatal dopamine deficiency secondary to degeneration of dopaminergic neurons in the substantia nigra. Selegiline is currently the most widely used monoamine oxidase-B inhibitor for Parkinson's disease, but has a low and variable bioavailability, and is metabolized to L-methamphetamine and L-amphetamine that carry a risk for potential neurotoxicity. There are two new approaches that circumvent these potential disadvantages. First, selegiline orally disintegrating tablets provide a novel delivery form of selegiline, avoiding first pass metabolism by rapid absorption through the oral mucosa, thus leading to significantly lower plasma concentrations of L-metamphetamine and L-amphetamine. Selegiline orally disintegrating tablets prove to be clinically effective and safe in patients with moderately advanced Parkinson's disease. Second, rasagiline is a new monoamine oxidase inhibitor, without known neurotoxic metabolites. In large clinical trials, rasagiline proves effective as monotherapy in early Parkinson's disease, as well as adjunctive therapy to levodopa in advanced disease. Clinical data suggest, in addition, a disease-modifying effect of rasagiline that may correlate with neuroprotective activity of monoamine oxidase-B inhibitors in animal models of Parkinson's disease.

Treatment of advanced Parkinson’s disease

Parkinson's disease is a progressive neurological disorder characterized by tremor, bradykinesia, rigidity, gait and postural instability and a variety of nonmotor symptoms. While these and other motor signs typically improve with levodopa, the so-called axial signs, such as dysarthria, dysphagia, postural instability and freezing, and most nonmotor signs, such as depression, cognitive decline and dysautonomia, usually do not respond satisfactorily to levodopa. Furthermore, the use of levodopa may be limited by the development of motor fluctuations, dyskinesias and other adverse effects. This manuscript reviews the medical management of advanced Parkinson's disease, focusing on the treatment of motor fluctuations and dyskinesias and of nonmotor and nonlevodopa responsive symptoms.

Summary of the recommendations of the EFNS/MDS-ES review on therapeutic management of Parkinson's disease

OBJECTIVE

To summarize the 2010 EFNS/MDS-ES evidence-based treatment recommendations for the management of Parkinson's disease (PD). This summary includes the treatment recommendations for early and late PD.

METHODS

For the 2010 publication, a literature search was undertaken for articles published up to September 2009. For this summary, an additional literature search was undertaken up to December 2010. Classification of scientific evidence and the rating of recommendations were made according to the EFNS guidance. In cases where there was insufficient scientific evidence, a consensus statement ('good practice point') is made.

RESULTS AND CONCLUSIONS

For each clinical indication, a list of therapeutic interventions is provided, including classification of evidence.

Treatment of motor symptoms in advanced Parkinson's disease: a practical approach

Patients with advanced Parkinson's disease (PD) are known to develop motor complications after a few years of levodopa (L-dopa) therapy. Motor fluctuations develop with increasing severity of the disease, owing to loss of dopaminergic neurons and loss of the buffering capacity of the neurons to fluctuating dopamine levels. Dyskinesias develop as a result of pulsatile stimulation of the receptors and alterations in neuronal firing patterns. L-dopa remains the gold standard medication for the treatment of patients with advanced PD. However, once motor complications on L-dopa therapy emerge, clinicians may add on other classes of antiparkinsonian drugs such as dopamine agonists, catechol-O-methyl transferase inhibitors (COMTIs) or monoamine oxidase type B inhibitors (MAOBIs). The individualisation of the treatment seems to be the key for the best approach of advanced PD patients. The present review provides the most important current clinical data in the pharmacological treatment of motor symptoms in advanced PD and provides the clinician a simple algorithm in order to determine the best suitable treatment to advanced parkinsonian patients.

Strategies for Parkinson’s disease care: prevention and management of motor fluctuations

SUMMARY Parkinson’s disease (PD) is characterized clinically by the hallmark motor signs of bradykinesia, rest tremor and rigidity. Current pharmacological management goals include control of motor symptoms as well as prevention and management of motor complications including motor fluctuations and dyskinesias. While the use of levodopa revolutionized the pharmacological management of PD, multiple other agents and strategies have emerged with many demonstrable, albeit sometimes controversial, advantages to a ‘levodopa’ only approach. Despite these developments, the progressive nature of PD requires vigilance and creativity from clinicians as both motor and nonmotor complications grow in number and severity over time.

Parkinson's disease and motor fluctuations

OPINION STATEMENT

Many important advances for the treatment of Parkinson's disease (PD) have been made over the past decade, and quality of life has improved for most patients. Nonetheless, motor fluctuations in the form of wearing off with the re-emergence of parkinsonian symptoms and hyperkinetic movements (dyskinesias) often arise as a complication of long-term dopaminergic therapy and can be disabling. Because treatment of motor fluctuations is difficult, clinicians should attempt to prevent them by using low doses of dopaminergic drugs in early PD, targeting functionally relevant symptoms. Instead of levodopa, dopamine agonists, amantadine, and rasagiline can be used with the aim of delaying the onset of motor fluctuations. Once motor fluctuations arise, off time can initially be addressed with more frequent dosing of levodopa. Later, adjunctive therapy with a dopamine agonist, COMT-inhibitor, or MAO-B inhibitor becomes necessary. For treatment of dyskinesias, reduction of the levodopa dose should be the first step. If this is not tolerated because of increased off time, then adjunctive therapy with levodopa-sparing agents should be attempted. The addition of amantadine (the only currently available antidyskinetic drug) is another useful strategy but is often only a temporary solution. Once medical attempts at treating motor fluctuations fail, deep brain stimulation (DBS) can be considered. Careful patient selection and skilled placement of DBS electrodes are important determinants of the surgical outcome.

Patient diaries as a clinical endpoint in Parkinson's disease clinical trials

Parkinson's disease (PD) is the second most common neurodegenerative disorder with an estimated 4 million patients worldwide. L-dopa is standard, and often initial, therapy for patients with this condition; however, with continued dopaminergic treatment and as the disease progresses, the majority of patients experience complications such as "wearing-off" symptoms, dyskinesias, and other motor complications. These complications may become disabling and profoundly affect quality of life. Treatment modification and combination therapies with L-dopa, dopamine agonists, monoamine oxidase type B inhibitors, and catechol-O-methyltransferase inhibitors are commonly used to manage complications. In recent years regulatory agencies, clinical researchers, and sponsors have widely accepted and utilized changes in "ON" and "OFF" time measured by Patient Hauser Diaries as endpoints for measuring efficacy of therapeutics seeking approval for symptomatic treatment of PD. Successful antiparkinsonian medications have been associated with treatment effects of more than 1 h in either reduction of "OFF" time of increase in "ON" time. Accurate "ON" and "OFF" time registration during clinical studies requires rigorous patient training. Reduced compliance, recall bias and diary fatigue are common problems seen with patient diary reported measures. Electronic diaries may help reducing some of these problems but may be associated with other challenges in large, multicenter studies.

Efficacy, safety, and patient preference of monoamine oxidase B inhibitors in the treatment of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease and the most treatable. Treatment of PD is symptomatic and generally focuses on the replacement or augmentation of levodopa. A number of options are available for treatment, both in monotherapy of early PD and to treat complications of advanced PD. This review focuses on rasagiline and selegiline, two medications that belong to a class of antiparkinsonian drugs called monoamine oxidase B (MAO-B) inhibitors. Topics covered in the review include mechanism of action, efficacy in early and advanced PD, effects on disability, the controversy regarding disease modification, safety, and patient preference for MAO-B inhibitors.

Evaluation of the efficacy and safety of adjuvant treatment to levodopa therapy in Parkinson s disease patients with motor complications

BACKGROUND

One of the complications of long-term treatment of Parkinson's disease (PD) with levodopa is the development of motor complications. Generally, when motor complications develop, clinicians add in an additional drug (to the levodopa regimen) from one of three other classes of anti-Parkinsonian treatments (dopamine agonists, catechol-O-methyl transferase inhibitors (COMTIs) or monoamine oxidase type B inhibitors (MAOBIs)). However, despite trials having shown that these drugs are beneficial compared to placebo, it remains unclear as to the best way to treat patients experiencing motor complications and whether one class of drug is more effective than another.

OBJECTIVES

This meta-analysis aims to assess more reliably the benefits and risks of the three classes of drugs (dopamine agonists, COMTIs and MAOBIs) currently used as adjuvant treatment to levodopa in PD patients suffering from motor complications. The three drug classes were compared with the aim of determining whether one class of drug provides better symptomatic control than another.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library), MEDLINE, EMBASE, PubMed, LILACS and Web of Science, plus major journals in the field, abstract books, conference proceedings and reference lists of retrieved publications.

SELECTION CRITERIA

Randomised trials comparing an orally administered dopamine agonist, COMTI or MAOBI versus placebo, both on a background of levodopa therapy, in PD patients experiencing motor complications.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data on off-time, levodopa dose, motor complications, side-effects, treatment concordance, clinician-rated disability, mortality, quality of life and health economic data.

MAIN RESULTS

Forty-four eligible trials, involving 8436 participants were identified. Compared to placebo, adjuvant therapy significantly reduced off-time (-1.05 hours/day, 95% confidence interval (CI) -1.19 to -0.90; P<0.00001), the required levodopa dose (-55.65 mg/day, CI -62.67 to -48.62; P<0.00001) and improved UPDRS scores (UPDRS ADL score: -1.31 points, CI -1.62 to -0.99; P<0.00001; UPDRS motor score: -2.84 points, CI -3.36 to -2.32; P<0.00001; UPDRS total score: -3.26 points, CI -4.52 to -2.00; P<0.00001). However, dyskinesia (odds ratio (OR) 2.50, CI 2.21 to 2.84; P<0.00001) and side-effects including constipation (OR 3.19, CI 2.17 to 4.68; P<0.00001), dizziness (OR 1.57, CI 1.30 to 1.90; P<0.00001), dry mouth (OR 2.33, CI 1.22 to 4.47; P=0.01), hallucinations (OR 2.16, CI 1.70 to 2.74; P<0.00001), hypotension (OR 1.47, CI 1.18 to 1.83; P=0.0007), insomnia (OR 1.38, CI 1.09 to 1.74; P=0.007), nausea (OR 1.78, CI 1.53 to 2.07; P<0.00001), somnolence (OR 1.87, CI 1.40 to 2.51; P<0.0001) and vomiting (OR 2.56, CI 1.67 to 3.93; P<0.0001) were all increased with adjuvant therapy.Indirect comparisons of the three drug classes suggested that dopamine agonists were more efficacious in reducing off-time (dopamine agonist: -1.54 hours/day; COMTI: -0.83 hours/day; MAOBI: -0.93 hours/day; test for heterogeneity between drug classes P=0.0003) and levodopa dose (dopamine agonist: -116 mg/day; COMTI: -52 mg/day; MAOBI: -29 mg/day; test for heterogeneity between drug classes P<0.00001). UPDRS scores also improved more with dopamine agonists than with COMTI or MAOBI (UPDRS total scores - dopamine agonist: -10.01 points versus COMTI: -1.46 points versus MAOBI: -2.20 points; test for heterogeneity between drug classes P<0.00001), although more dyskinesia were seen with dopamine agonists (OR 2.70) and COMTI (OR 2.50) than with MAOBI (OR 0.94) (test for heterogeneity between drug classes P=0.009). Although the increase in the overall incidence of side-effects was generally more marked with dopamine agonists (OR 1.52) and COMTI (OR 2.0) than with MAOBI (OR 1.32), heterogeneity between drug classes was only of borderline significance (P=0.07).

AUTHORS' CONCLUSIONS

Compared to placebo, adjuvant therapy reduces off-time, levodopa dose, and improves UPDRS scores in PD patients who develop motor complications on levodopa therapy. However, this is at the expense of increased dyskinesia and numerous other side-effects. Indirect comparisons suggest that dopamine agonist therapy may be more effective than COMTI and MAOBI therapy, which have comparable efficacy. However, as indirect comparisons should be interpreted with caution, direct head-to-head randomised trials assessing the impact of these different drug classes on overall patient-rated quality of life are needed.

Treatment of levodopa-induced motor complications

Chronic levodopa treatment for Parkinson's disease patients is frequently associated with the development of motor complications such as end-of-dose wearing-off and dyskinesias. In this review, we provide an overview of the strategies available for dealing with these problems. Medical management includes manipulation of levodopa dosing to establish the optimum treatment schedule, improving levodopa absorption, catechol-O-methyl transferase-inhibition (COMT), Monoamine oxidase-B (MAO-B) inhibition, dopaminergic agonists, amantadine, and continuous dopaminergic infusions. Surgical procedures and particularly deep brain stimulation are also reviewed. It should be noted that none of these treatments has been shown to provide anti-parkinsonian efficacy that is greater than what can be achieved with levodopa. We highlight the importance of initiating therapy with a treatment strategy that reduces the risk that a Parkinson's disease patient will develop motor complications in the first place. Key Words: Advanced PD, dyskinesias, motor fluctuations, levodopa, dopamine agonists, COMT inhibitors, MAO-B inhibitors.

Orally disintegrating selegiline for the treatment of Parkinson's disease

The selective monoamine oxidase type B inhibitor selegiline is commonly administered as medical treatment to patients suffering from Parkinson's disease. The clinical value of conventional selegiline is, however, compromised by extensive first-pass metabolism, which reduces its bioavailability and leads to the production of possibly harmful methamfetamine metabolites. This review aims to evaluate a novel, orally disintegrating formulation of selegiline by examining scientific evidence from previous pharmacological and clinical studies. As a result of improved bioavailability, orally disintegrating selegiline can be administered at lower doses than conventional selegiline with similar clinical effect. It also leads to less variable selegiline blood concentrations and produces significantly less methamfetamine metabolites. We conclude that this novel formulation offers an interesting treatment option, especially for patients who report adverse events after initial treatment with conventional selegiline or who suffer from swallowing difficulties.

Medical management of motor fluctuations

Given the magnitude of the problem of motor fluctuations in patients who have Parkinson's disease treated with levodopa, a significant effort has been expended by physicians, researchers, and pharmaceutical manufacturers over the years to find effective treatments. This article briefly reviews the medical options for managing motor fluctuations that are in common use in the United States or that are expected to be available soon.

Current status of symptomatic medical therapy in Parkinson's disease

Symptomatic medical therapies for Parkinson's disease (PD) have been disease modifying and have led to improvement in daily function, quality of life, and survival. For 40 years, these therapies have been primarily dopaminergic, and currently include the dopamine (DA) precursor levodopa (LD), DA agonists, catechol-O-methyltransferase (COMT) inhibitors, and monoamine oxidase (MAO) inhibitors. The roles of all these classes of agents have evolved, with significant changes occurring since the early 2000s. This article reviews the current literature for each of these classes of drugs, with a focus on efficacy and place in the therapeutic scheme. Levodopa is no longer considered to be toxic and, thus, its early use is not only appropriate but recommended. Ergot agonists are no longer in use, and new agents administered in patch form or subcutaneous injections have been approved. The COMT inhibitor tolcapone, with its significant efficacy, has been reintroduced, and two new MAO inhibitors have been approved. Selected safety issues are discussed, including the incidence of melanoma in relation to LD; pathological gambling and DA agonists; hepatic toxicity of tolcapone; and the tyramine or so-called cheese reaction with MAO B inhibitors. The article closes with a discussion of future directions and new drugs under development.

Motor complications in Parkinson disease: Clinical manifestations and management

Long-term dopaminomimetic therapy, not limited to levodopa, is complicated by the emergence of variations of motor response in a majority of Parkinson disease (PD) patients. These variations can occur in different forms, as early wearing off during the initial stage of motor complications, dyskinesias in the intermediate stage, and complex fluctuations in the advanced stage. Considered to be a major source of disability in advanced PD patients, recognition of these complications is critical in order to develop different strategies designed not only to treat these problems when they develop, but also to prevent troublesome complications associated with potential risk factors. In this article, authors classify a wide clinical spectrum of motor complications into different stages as the disease progresses through the treatment. A number of strategies are proposed in order to manage these complications as well as to avoid them. Better understanding of these potential complications will result in better management of these problems and lessen the disability associated with advanced PD.

Community and Long-Term Care Management of Parkinson???s Disease in the Elderly

Parkinson's disease affects up to 1 million people in the US, most of them elderly. Motor and non-motor symptoms can be significantly disabling to the point of necessitating institutionalisation. Age-related changes in drug absorption, distribution, metabolism and excretion complicate the treatment of elderly patients with Parkinson's disease. General management principles include initiation of medication at low doses with gradual titration based on clinical effects, avoidance of certain classes of drugs (e.g. anticholinergics), and attention to polypharmacy and its risk for potentially toxic drug interactions. Levodopa remains the most efficacious anti-Parkinson's disease medication and should be the cornerstone of therapy in the elderly Parkinson's disease patient. Use of dopamine receptor agonists, amantadine and anticholinergic drugs in the elderly is limited by high risk for psychotoxicity. Catechol-O-methyltransferase inhibitors may be used to augment levodopa in the setting of 'wearing off' (i.e. motor fluctuations). Monoamine oxidase type B (MAO-B) inhibitors can be used across the spectrum of disease severity, but selegiline (deprenyl), the prototype in this class, is characterised by low and erratic bioavailability of the parent drug and conversion to amphetamine metabolites that may increase the risk of adverse events. A new orally disintegrating tablet formulation overcomes some of these limitations. Rasagiline is a new, selective, second-generation MAO-B inhibitor that is chemically and metabolically distinct from selegiline. The favourable safety profile of rasagiline in the elderly and its once-daily formulation may maximise drug adherence and improve outcomes.

Review of the therapeutic management of Parkinson's disease. Report of a joint task force of the European Federation of Neurological Societies (EFNS) and the Movement Disorder Society-European Section (MDS-ES). Part II: late (complicated) Parkinson's disease

To provide evidence-based recommendations for the management of late (complicated) Parkinson's disease (PD), based on a review of the literature. Complicated PD refers to patients suffering from the classical motor syndrome of PD along with other motor or non-motor complications, either disease-related (e.g. freezing) or treatment-related (e.g. dyskinesias or hallucinations). MEDLINE, Cochrane Library and INAHTA database literature searches were conducted. National guidelines were requested from all EFNS societies. Non-European guidelines were searched for using MEDLINE. Part II of the guidelines deals with treatment of motor and neuropsychiatric complications and autonomic disturbances. For each topic, a list of therapeutic interventions is provided, including classification of evidence. Following this, recommendations for management are given, alongside ratings of efficacy. Classifications of evidence and ratings of efficacy are made according to EFNS guidance. In cases where there is insufficient scientific evidence, a consensus statement ('good practice point') is made.

Advances in the delivery of treatments for Parkinson's disease

Innovative drug delivery in Parkinson's disease (PD) has the potential to reduce or avoid many side effects of current treatment, such as wearing-off type fluctuations, dyskinesia, on-off phenomena or bouts of motor freezing. The traditional orally administered formulations of l-dihydroxyphenylalanine combined with a peripheral aromatic acid decarboxylase inhibitor remain the mainstay of treatments for PD. However, such combination therapies have been further formulated to extend their duration of action by including a catechol-O-methyltransferase inhibitor. Preventing the breakdown of dopamine has also been achieved by monoamine oxidase-B inhibition; this approach now having been formulated for sublingual use (Zelapar, Valeant Pharmaceuticals). An alternative approach bypasses the oral route of administration and instead relies on continuous duodenal infusion (Duodopa, Solvay, NeoPharma AB) for better therapeutic effect. The clinical use of dopamine agonists as antiparkinsonian drugs now incorporates a variety of delivery techniques. For example, apomorphine, which relies on parenteral administration for maximum bioavailability, may be delivered via rectal, intranasal, sublingual and subcutaneous (e.g., Apokyn, Mylan Bertek) routes. Meanwhile, rotigotine and lisuride have both been formulated for delivery via skin patches. Finally, the authors examine more experimental delivery techniques, including the delivery of genes via viral vectors or liposomes, intracranial transplant of a variety of cells and of L-dihydroxyphenylalanine by prodrug-dispensing liposomes or pulmonary delivery (AIR, Alkermes). The advent and application of these varied technologies will help encourage patient-specific means of treatment for PD.

Rasagiline-associated motor improvement in PD occurs without worsening of cognitive and behavioral symptoms

BACKGROUND

Cognitive and behavioral adverse events (AEs) such as hallucinations, confusion, depression, somnolence and other sleep disorders commonly limit effective management of motor symptoms in PD. Rasagiline (N-propargyl-1(R)-aminoindan) mesylate is a novel, second-generation, selective, irreversible monoamine oxidase type B inhibitor, demonstrated in monotherapy and adjunctive trials to be effective for PD with excellent tolerability.

METHODS

The occurrence of cognitive and behavioral AEs and the change from baseline in the Unified Parkinson's Disease Rating Scale (UPDRS) part I mental subscores were reviewed in two multicenter, randomized, placebo-controlled, 26-week trials of rasagiline for early and moderate-to-advanced patients with PD. The UPDRS is a multi-item rating scale specific to PD; part I rates the patient's intellectual impairment, thought disorders, depression and motivation/initiative.

RESULTS

The TEMPO study evaluated rasagiline monotherapy in early PD patients (n=404). The PRESTO study evaluated rasagiline as adjunctive therapy in moderate-to-advanced PD patients with motor complications who were receiving optimized levodopa/carbidopa (n=472). In the analysis of adverse event reporting for both studies, no cognitive and behavioral AE in either the rasagiline 1 mg or placebo groups exceeded 10% of the study population and the frequency differences between rasagiline 1 mg and placebo never exceeded 3%. There was no adverse effect on the UPDRS mental subscore relative to placebo in either of the two studies.

CONCLUSION

Rasagiline 1 mg once daily improves PD symptoms and motor fluctuations in early and moderate-to-advanced PD patients without causing significant cognitive and behavioral AE or adverse changes in mentation, behavior and mood.

Reversion of levodopa-induced motor fluctuations by the A2A antagonist CSC is associated with an increase in striatal preprodynorphin mRNA expression in 6-OHDA-lesioned rats

The molecular mechanisms involved in the reversion of levodopa-induced motor fluctuations by the adenosine A2A antagonist 8-(3-chlorostryryl) caffeine (CSC) were investigated in rats with a 6-hydroxydopamine (6-OHDA)-induced lesion and compared with the ones achieved by the kappa-opioid agonist, U50,488. Animals were treated with levodopa (50 mg/kg/day) for 22 days and for one additional week with levodopa + CSC (5 mg/kg/day), levodopa + U50,488 (1 mg/kg/day), or levodopa + vehicle. The reversion of the decrease in the duration of levodopa-induced rotations by CSC, but not by U50,488, was maintained until the end of the treatment and was associated with a further increase in levodopa-induced preprodynorphin mRNA in the lesioned striatum, being higher in the ventromedial striatum. The increase in striatal preprodynorphin expression, particularly in the ventromedial striatum, may be related to the reversion of levodopa-induced motor fluctuations in the CSC-treated animals, suggesting a role of the direct striatal output pathway activity in the ventromedial striatum in the pathophysiology of motor fluctuations.

Zydis selegiline reduces off time in Parkinson's disease patients with motor fluctuations: a 3-month, randomized, placebo-controlled study

Zydis selegiline dissolves on contact with saliva and undergoes pregastric absorption. This minimizes first-pass metabolism and provides high plasma concentrations of selegiline. In this study, the efficacy and safety of Zydis selegiline was assessed in Parkinson's disease (PD) patients who were experiencing motor fluctuations with levodopa. Patients were randomly assigned to either drug or placebo in a 2:1 ratio in this double-blind, multicenter trial. Significant reductions in daily off time occurred at 4 to 6 weeks with the 1.25 mg dose (9.9%, P = 0.003) and 10 to 12 weeks with the 2.5 mg dose (13.2%, P < 0.001). The total number of off hours was reduced by 2.2 hours at Week 12 from baseline (compared with 0.6 hours in the placebo group). The average number of dyskinesia-free on hours for the Zydis selegiline patients increased by 1.8 hours at Week 12. There was no change in mean percentage of "Asleep" time throughout the study. No apparent differences were detected in the occurrence of drug-related adverse events between the Zydis selegiline group and placebo-treated groups. Adverse events were consistent with known effects of levodopa therapy. Zydis selegiline safely reduces daily off time when used as adjunctive therapy with levodopa in patients with PD.

Parkinson's disease: medical and surgical treatment

It has been over three decades since the introduction of L-dihydroxyphenylalanine or levodopa therapy for Parkinson's disease (PD). The early levodopa trials were driven by recognition of a profound cerebral dopamine deficiency state in this disorder. Whereas dopamine fails to cross the blood brain barrier and hence is ineffective as therapy, the amino acid precursor, dopa, is transported across this barrier and provides a substrate for dopamine synthesis. Levodopa is converted to dopamine within the brain by dopa decarboxylase, replenishing central dopamine stores and potentially reversing the motor symptoms of PD.

5: Movement disorders I: parkinsonism and the akinetic-rigid syndromes

The major features of akinetic-rigid syndromes are bradykinesia (small, slow movements), rigidity and tremor, often summarised as "parkinsonism". Approximately 80% of akinetic-rigid syndromes are due to Parkinson's disease. Treatment of Parkinson's disease should be determined by level of disability and handicap. The combination of levodopa and peripheral dopadecarboxylase inhibitor is the most efficacious symptomatic treatment for Parkinson's disease. Motor fluctuations appear after 2-3 years of levodopa treatment, and affect at least 50% of patients after five years. Surgery can relieve refractory tremor and dyskinesias, but does not alter disease progression or need for drug therapy.

Effect of MAO-B inhibitors on MPP+ toxicity in Vivo

l-Deprenyl (Selegiline), a selective and irreversible type B monoamine oxidase inhibitor, has been used as an adjunct to levodopa therapy in Parkinson's disease. Recently, it is proposed as a putative neuroprotective agent in delaying the progression of cell death based on its capability of reducing the oxidative stress derived from the MAO-B dependent metabolism of dopamine, and blocking the development of MPTP-parkinsonism. However, a variety of experimental models suggest that l-deprenyl provides neuroprotection through multiple modes of mechanism other than the inhibition of MAO-B. We have previously shown that l-deprenyl protects midbrain dopamine neurons from MPP+ toxicity by a novel antioxidant effect. In the present study we examined whether the protection against MPP+ toxicity is also shared by other reversible or irreversible MAO-B inhibitors including (+)-deprenyl, Ro16-6491 and pargyline. Our data show that non of these MAO-B inhibitors changes the dopamine loss in the striatum induced by intranigral injection of MPP+. Our result suggests that l-deprenyl may possess a unique neuroprotective action on nigral neuron against MPP+ toxicity independent of the MAO-B inhibition.

Medical treatment of later-stage motor problems of Parkinson disease

Parkinson disease progression is associated with the development of levodopa short-duration responses and dyskinesias, as well as gait freezing. Levodopa dose adjustment and adjunctive treatment with dopamine agonists form the major therapeutic strategies. Catechol O-methyltransferase inhibitors are also appropriate considerations, whereas other drugs, including selegiline, amantadine, anticholinergic agents, and propranolol, have a more minor role.

Current management of motor fluctuations in patients with advanced Parkinson's disease treated chronically with levodopa

Motor fluctuations after long-term administration of levodopa may be due to central pharmacodynamic mechanisms such as reduced striatal synthesis and storage of dopamine from exogenous levodopa and subsensitization of postsynaptic dopaminergic receptors. Peripheral pharmacokinetic mechanisms may be equally important, particularly in motor fluctuations of the "delayed on" (increased time latencies from dose intake to start-up of clinical benefit) and "no-on" (complete failure of a levodopa dose to exert an "on" response) types. Levodopa itself has a very poor solubility. In addition, there is delayed gastric emptying in many advanced patients. Therefore, an oral dose of levodopa may remain in the stomach for long periods of time before it passes into the duodenum where there is immediate absorption. Consequently, in order to overcome response fluctuations caused by impaired pharmacokinetic mechanisms and to improve its absorption, we recommend that levodopa be taken in multiple small doses, on an empty stomach, preferably crushed and mixed with a lot of liquid. Protein intake should be minimized. Prokinetic drugs such as prepulsid (Cisaprid) could be used to facilitate gastric motility and levodopa transit time. Administration of crushed levodopa through nasoduodenal or gastrojejunostomy tubes may be helpful in certain circumstances. Bypassing the stomach with subcutaneous injections of apomorphine may provide dramatic rescue from difficult "off" situations. Oral and s.c. administration of novel, extremely soluble prodrugs of levodopa, e.g., levodopa ethylester, may offer a new approach to overcome difficulties in levodopa absorption. Addition of dopamine agonists, MAO-B inhibitors, COMT inhibitors and controlled release levodopa preparations may be helpful in prolonging the duration of efficacy of each single levodopa dose. Levodopa, administered orally, usually combined with peripheral dopa decarboxylase inhibitors, continues to be the most widely-used and most effective pharmacological treatment for Parkinson's disease (Melamed, 1987). Undoubtedly, the outstanding therapeutic success of levodopa represents a dramatic and revolutionary breakthrough in medicine, in general, and in neurology, in particular. Although, since the introduction of levodopa, there have been many additional pharmacological and even surgical anti-parkinsonian strategies, it still stands out as a mandatory axis of treatment in the majority of patients (Steigler and Quinn, 1992). Indeed, levodopa therapy improves, sometimes markedly, the motor signs and symptoms of the illness, the functional capacity and quality of life and perhaps also life expectancy of the afflicted patients. It is therefore unfortunate that after an initial problem-free period of successful, smooth and stable clinical benefit from levodopa that lasts about two to five years, the responsiveness of many patients worsens with the emergence of a variety of complications (Marsden et al., 1982; Hardie et al., 1984). These adverse reactions include dyskinesias and dystonias, psychotic problems and, particularly, the troublesome motor fluctuations (Marsden and Parkes, 1977; Marsden, 1994). The latter phenomenon may be particularly complex, limiting and disabling. It is believed that most patients on long-term levodopa therapy will, sooner or later, develop response fluctuations of varying types and severity (Riley and Lang, 1993). Because of the serious impact of these phenomena on the quality of life and function of the patients, many efforts are now being undertaken to identify the responsible mechanisms and to devise preventive and therapeutic measures.

Dopaminergic pharmacology and antioxidant properties of pukateine, a natural product lead for the design of agents increasing dopamine neurotransmission

The dopaminergic and antioxidant properties of pukateine [(R)-11-hydroxy-1,2-methylenedioxyaporphine, PUK], a natural aporphine derivative, were analyzed in the rat central nervous system. At dopamine (DA) D1 ([3H]-SCH 23390) and D2 ([3H]-raclopride) binding sites, PUK showed IC50 values in the submicromolar range (0.4 and 0.6 microM, respectively). When the uptake of tritiated dopamine was assayed by using a synaptosomal preparation, PUK showed an IC50 = 46 microM. In 6-hydroxydopamine unilaterally denervated rats, PUK (8 mg/kg but not 4 mg/kg) elicited a significant contralateral circling, a behavior classically associated with a dopaminergic agonist action. When perfused through a microdialysis probe inserted into the striatum, PUK (340 microM) induced a significant increase in dopamine levels. In vitro experiments with a crude rat brain mitochondrial suspension showed that PUK did not affect monoamine oxidase activities, at concentrations as high as 100 microM. PUK potently (IC50 = 15 microM) and dose-dependently inhibited the basal lipid peroxidation of a rat brain membrane preparation. As a whole, PUK showed a unique profile of action, comprising an increase in extracellular DA, an agonist-like interaction with DA receptors, and antioxidant activity. Thus, PUK may be taken as a lead compound for the development of novel therapeutic strategies for Parkinson disease.

Parkinson's Disease: Motor Fluctuations

Motor fluctuations represent important late complications of Parkinson's disease treated with levodopa. Although treatment of these problems has improved with the emergence of numerous pharmacologic and surgical therapies, the various options can make it confusing. Pharmacologic treatment is the first step. Polytherapy is often the rule in this case with a variety of agents available as adjunctive therapy with levodopa. These adjuncts include dopamine agonists (bromocriptine, pergolide, pramipexole, ropinirole), catechol-O-methyltransferase (COMT) inhibitors (tolcapone), controlled-release formulations of levodopa, monoamine oxidase (MAO) B inhibitors (selegiline), and amantadine. The treatment can consist of any of a number of combinations of these agents. No single algorithm can be used in all patients; therapy should be individualized. Physicians treating these patients need to be well versed in late complication patterns as well as the medications chosen. In addition, optimal doses vary, and often patients are considered treatment failures and taken off medications before reaching that level. In the more complicated cases, patients should be evaluated by specialists in movement disorders. With this in mind, some guidelines are offered for the pharmacologic approach to patients with fluctuating responses to medications. For simple wearing off, controlled-release levodopa (Sinemet CR, Dupont Pharmaceuticals, Wilmington, DE), COMT inhibitors, MAO inhibitors, and dopamine agonists are reasonable options. For more complicated fluctuations, dopamine agonists with limits on levodopa are the first choice, especially when dyskinesia is present; when dyskinesia is not a factor, COMT inhibitors may be used. For dyskinesia specifically, dopamine agonists or addition of amantadine can be helpful. Surgery should be a treatment of last resort for patients in whom medical therapy fails. Patients who are candidates for medial pallidotomy should be fluctuators with severe dyskinesia and "off" periods that have not improved with pharmacologic therapy. Thalamic deep brain stimulation (DBS) should be used only in patients with tremor-predominant disease and severe intractable tremor that is unresponsive to medication and occurs not only at rest but with posture and action as well. Surgical therapy should be performed only in centers with surgeons experienced in stereotactic techniques and movement disorder specialists to ensure that the appropriate patients come to surgery and that complications are kept to a minimum. Dietary adjustment has a limited role in treating advanced Parkinson's disease.

Monoamine oxidase and catechol-O-methyltransferase inhibitors

Despite advances in the treatment of PD, there remain significant unmet therapeutic needs. This is particularly true at the later stages of the disease when dopaminergic therapy is complicated by motor fluctuations and dyskinesias. Inhibition of dopamine metabolism is a valuable adjunct to exogenous dopaminergic replacement. Inhibitors of MAO-B have been used to treat early and advanced PD for a number of years. Although controversy remains, existing evidence still raises the possibility that MAO-B inhibition may confer a protective effect in PD, delaying the progression of the underlying pathology. More recently, clinically useful inhibitors of COMT have become available. These medications largely act peripherally to increase the pool of available dopamine precursor and prolong the duration of effect of L-dopa. They are indicated primarily for control of motor fluctuations.

Entacapone improves motor fluctuations in levodopa-treated Parkinson's disease patients. Parkinson Study Group

Motor fluctuations associated with levodopa therapy are common problems encountered in the long-term treatment of Parkinson's disease (PD). Entacapone, a peripherally acting, reversible inhibitor of catechol-O-methyltransferase, slows the elimination of levodopa in humans by reducing the formation of 3-O-methyldopa. We conducted a placebo-controlled, double-blind, parallel-group, multicenter trial of entacapone in PD patients with motor fluctuations. Two hundred five patients were randomized to receive either entacapone 200 mg or matching placebo with each dose of levodopa and were followed for 24 weeks. The primary measure of efficacy was the change in percentage of "on" time (relief of parkinsonism) while awake, as recorded by subjects at home in diaries completed at 30-minute intervals. At baseline, patients averaged approximately 10 hours of "on" time per day while awake (60.5% "on" time), and entacapone treatment increased the percent "on" time by 5.0 percentage points. The effect of entacapone was more prominent in patients with a smaller percent "on" time (<55%) at baseline, and increased as the day wore on. Entacapone is effective at increasing the duration of response to levodopa and at relieving parkinsonism in patients experiencing motor fluctuations and was well tolerated during the 24 weeks of treatment.

Problems with current pharmacologic treatment of Parkinson's disease

For the past 30 years levodopa (LD) has been the pharmacologic standard of care for treating idiopathic parkinsonism (Parkinson's disease or PD), a neurodegenerative disease of the central nervous system. LD is a pharmacologically inactive precursor, which is converted enzymatically to the neurotransmitter dopamine by a declining population of neurons in the substantia nigra, the most important site of the pathology of PD. Most patients experience a smooth, lasting response to small amounts of LD during the early years of treatment, but as the underlying disease gets worse, treatment-related problems arise. Motor fluctuations, which slowly emerge after 3-5 years of chronic LD therapy, gradually replace the smooth pattern of response, and more frequent dosing is required. Abnormal involuntary movements (dyskinesia), wearing-off of the motor response after a few hours, organic psychosis (confusion and hallucinations), and progressive loss of independence characterize the complicated interaction between the drug and the disease. Despite its problems, including the theoretical potential for harming neurons by inducing oxidant stress, and the recent development of other antiparkinson drugs, LD remains the most effective pharmacologic agent available for the relief of symptoms in patients with PD.

Treatment of early Parkinson's disease: are complicated strategies justified?

A variety of medical treatment strategies have been proposed as a means of slowing the progression of Parkinson's disease. This includes administration of selegiline (deprenyl) therapy, early use of bromocriptine or pergolide, and delay of levodopa therapy or restriction of the dose. There is no compelling evidence supporting the use of any of these treatment strategies for this purpose. Carbidopa-levodopa remains the most potent medication for symptomatic treatment of Parkinson's disease. Although starting levodopa therapy with the controlled-release formulation is advocated, this does not appear to have any major advantages over standard carbidopa-levodopa. Further studies are needed to identify other means of halting the progression of Parkinson's disease.