The initial treatment of Parkinson's disease should begin with levodopa

Hallmarks of Clinical Aspects of Parkinson's Disease Through Centuries

James Parkinson published a treatise "An Essay on The Shaking Palsy" in 1817. However, there is historical evidence that there were rudimentary descriptions of the disease long before Parkinson brought it to light. Later day physicians have added to the spectrum of the motor aspects of the disease over the last 200 years and the gamut of its clinical presentation is now known to be more ubiquitous than what was supposed earlier. In the 1960s, atypical Parkinsonism is identified as a distinct and separate entity, and after the introduction of levodopa in clinical practice, a variety of late motor complications have been described. Various stages of disability and motor scales have been devised which have helped in identifying and classifying the degree of severity of the disease. However, such impeccable was the original description that virtually little could be modified and later works have only added to the original text.

Modulation of cAMP-specific PDE without emetogenic activity: new sulfide-like PDE7 inhibitors

A forward chemical genetic approach was followed to discover new targets and lead compounds for Parkinson's disease (PD) treatment. By analysis of the cell protection produced by some small molecules, a diphenyl sulfide compound was revealed to be a new phosphodiesterase 7 (PDE7) inhibitor and identified as a new hit. This result allows us to confirm the utility of PDE7 inhibitors as a potential pharmacological treatment of PD. On the basis of these data, a diverse family of diphenyl sulfides has been developed and pharmacologically evaluated in the present work. Moreover, to gain insight into the safety of PDE7 inhibitors for human chronic treatment, we evaluated the new compounds in a surrogate emesis model, showing nonemetic effects.

Phosphodiesterase Inhibitors as a New Therapeutic Approach for the Treatment of Parkinson’s Disease

Phosphodiesterases (PDEs) are expressed in different brain areas including the striatum. PDEs have recently emerged as important drug targets for central nervous system disorders, including Parkinson’s disease (PD). Levels of cyclic adenosine monophosphate (cAMP) control many cellular signaling pathways and are crucial for the dopamine signal, which is disturbed in PD due to the progressive loss of dopaminergic neurons. PDEs play a key role in cAMP homeostasis, as they are the enzymes responsible for its degradation. Moreover, beyond dopamine neurotransmission, cAMP is involved in many other cellular processes, such as neuroinflammation and neuronal plasticity. This enhances the value of PDEs as promising pharmacological targets for neurological disorders. Furthermore, cAMP‐PDE inhibitors with drug profiles may be used in the near future as disease‐modifying drugs for the treatment of PD. A concise review of the main roles of cAMP‐PDEs expressed in the striatum and the potential of their inhibitors in different animal models of PD is described in this chapter.

Factors determining when to start levodopa/carbidopa/entacapone treatment in Spanish patients with Parkinson's disease

INTRODUCTION

Several therapeutic options are available for the symptomatic treatment of Parkinson's disease (PD).There is no reliable information about which factors are involved in the choice of treatment.

OBJECTIVE

To identify factors contributing to the decision to start treatment with levodopa/carbidopa/entacapone (LCE) in patients with PD.

PATIENTS AND METHODS

We completed a descriptive cross-sectional retrospective multicentre study of patients with idiopathic PD receiving LCE. Clinical data were collected with special attention to factors that could potentially determine when to initiate treatment with LCE in normal clinical practice.

RESULTS

We studied 1050 patients with a mean age of 71.3±8.7 years (58.2% men). Average time from onset of symptoms to diagnosis was 13.8±12.9 months, with a latency time of 74.5±53.6 months before starting LCE treatment. The most common initial symptoms were tremor (70.6%), reduced dexterity (43.2%) and slowness of movement (41.5%). At the start of LCE treatment, most patients were in Hoehn and Yahr stage 2 (57.5%), with an average rating of 73.4% on the Schwab & England scale. Eight hundred twenty two patients (78.3%) received treatment with other drugs before starting LCE (mean time between starting any PD treatment and starting LCE was 40.5±47.2 months). Clinical factors with a moderate, marked, or crucial effect on the decision to start LCE treatment were bradykinesia (84.7%), daytime rigidity (72.2%), general decline (72.2%), difficulty walking (66.4%), tremor (62.7%), nocturnal rigidity (56.1%), and postural instability (53%). Difficulty performing activities of daily living was the only psychosocial factor identified as having an influence on the decision (84.3%).

CONCLUSIONS

The decision to start patients with idiopathic PD on LCE treatment is mainly determined by motor deficits and disabilities associated with disease progression.

Dyskinesias and treatment with pramipexole in patients with Parkinson's disease

Dopamine agonists such as pramipexole (PPX) have first been proposed as adjunctive treatment to levodopa (L-DOPA) for patients with Parkinson's disease (PD) and then as a monotherapy alternative to alleviate dyskinesia. Treatment with PPX has overall been associated with improvement in parkinsonian symptoms. Although the majority of placebo-controlled studies demonstrated that dyskinesia was more prevalent in the PPX compared to the placebo groups, some studies did not detect any dyskinesia as a side effect of this medication. PPX was consistently associated with lower risk for developing dyskinesia compared to L-DOPA. Moreover, the presence of these symptoms in the placebo groups suggests involvement of non-PPX-related factors for developing dyskinesia. It is suggested that future research should aim at ascertaining whether cotherapy with L-DOPA, PPX dosage, and other patient characteristics are contributory factors for the development of PPX-related dyskinesia in patients with PD.

New non-oral drug delivery systems for Parkinson's disease treatment

INTRODUCTION

Parkinson's disease (PD) remains the only neurodegenerative disorder for which there are highly effective symptomatic therapies, but still unmet needs regarding its long-term management. Levodopa (LD) remains the most effective treatment; however, chronic use is associated with potentially disabling motor complications.

AREAS COVERED

This review highlights a variety of new non-oral drug delivery strategies for non-invasive and invasive routes of drug administration for the treatment of PD. It also includes current and future trends of liposomes, solid lipid nanoparticles and biocompatible microparticles as new non-oral drug delivery systems.

EXPERT OPINION

The long-term complications and limitations of LD treatment might be improved by changing therapy from the present pulsatile stimulation to a more constant stimulation of central dopamine receptors. Stimulation of these receptors may be possible with a new non-oral drug delivery system, with the aim of achieving long-lasting and less fluctuating drug levels, minimization of peak levels and thereby reduction of side effects.

l-Dopa-induced dyskinesia-clinical presentation, genetics, and treatment

Levodopa-induced dyskinesia (LID) has been recognized since the introduction of levodopa for the management of Parkinson's disease (PD) and continues to be one of the most clinically challenging factors in long-term management of patients with PD. Most patients develop LID within 10 years of PD onset and the cause has been attributed to various factors including disease demographics, pharmacological, and possibly genetic causes. The clinical pattern of LID varies and shows intra and inter-patient variability and has been classified based upon phenomenology and relation to timing of levodopa. The potential armamentarium to address and manage LID has significantly increased in the last decade. This chapter addresses the current understanding of various clinical aspects and available therapeutics for LID.

From the cell to the clinic: a comparative review of the partial D₂/D₃receptor agonist and α2-adrenoceptor antagonist, piribedil, in the treatment of Parkinson's disease

Though L-3,4-dihydroxyphenylalanine (L-DOPA) is universally employed for alleviation of motor dysfunction in Parkinson's disease (PD), it is poorly-effective against co-morbid symptoms like cognitive impairment and depression. Further, it elicits dyskinesia, its pharmacokinetics are highly variable, and efficacy wanes upon long-term administration. Accordingly, "dopaminergic agonists" are increasingly employed both as adjuncts to L-DOPA and as monotherapy. While all recognize dopamine D(2) receptors, they display contrasting patterns of interaction with other classes of monoaminergic receptor. For example, pramipexole and ropinirole are high efficacy agonists at D(2) and D(3) receptors, while pergolide recognizes D(1), D(2) and D(3) receptors and a broad suite of serotonergic receptors. Interestingly, several antiparkinson drugs display modest efficacy at D(2) receptors. Of these, piribedil displays the unique cellular signature of: 1), signal-specific partial agonist actions at dopamine D(2)and D(3) receptors; 2), antagonist properties at α(2)-adrenoceptors and 3), minimal interaction with serotonergic receptors. Dopamine-deprived striatal D(2) receptors are supersensitive in PD, so partial agonism is sufficient for relief of motor dysfunction while limiting undesirable effects due to "over-dosage" of "normosensitive" D(2) receptors elsewhere. Further, α(2)-adrenoceptor antagonism reinforces adrenergic, dopaminergic and cholinergic transmission to favourably influence motor function, cognition, mood and the integrity of dopaminergic neurones. In reviewing the above issues, the present paper focuses on the distinctive cellular, preclinical and therapeutic profile of piribedil, comparisons to pramipexole, ropinirole and pergolide, and the core triad of symptoms that characterises PD-motor dysfunction, depressed mood and cognitive impairment. The article concludes by highlighting perspectives for clarifying the mechanisms of action of piribedil and other antiparkinson agents, and for optimizing their clinical exploitation.

Slowly progressive dopamine cell loss--a model on which to test neuroprotective strategies for Parkinson's disease?

Making animal models of human disease is a very flawed process. Aspects of the disease can be imitated but models do not necessarily give reliable leads for treatment strategies. When Ungerstedt in Sweden first described the 6-hydroxydopamine (6-OHDA) treated rat model of Parkinson's disease /89/ we knew that the symptoms would not map readily to those of the human disease--rats have four legs after all. On the other hand, the neuropathology looked exactly like end-stage Parkinsonian pathology. That remained true even as we explored other types of neuropathology in the rats /24,43-46,80/. Many of today's treatments for Parkinsonism are developed from pharmacological studies on that model of rats with a chemically induced lesion. However, the 6-OHDA model does not address the important issue of a cure for the disease. The triggers and the time-course of dopamine (DA) cell death in rats are known for nearly every disease model - but for the human disease there is no equivalent knowledge. In the human, the neurons have been dying for a considerable time before the symptoms become obvious and they go on dying even with adequate symptomatic relief /94/, but after intracerebral administration of 6-OHDA to an animal the cells die quickly; all cells are destroyed in less than 5 days /42,88,89/. Thus, we were interested in developing an animal model of DA cell death with a slower time-course. After ibotenic acid injections into rat globus pallidus (GP), DA cells are lost from the ipsilateral substantia nigra over the slower time scale of about six weeks. This time scale has allowed us to test some interventions to prevent the cells from dying. Although some attempts have succeeded, cell death is prevented only for three weeks -beyond that treatments fail and DA cells die. At the moment, this model has at least opened a window into causes of neuronal death in a slower time scale /94/ than previous rodent models.

Disease-modifying drugs and Parkinson's disease

Symptomatic medications, l-Dopa and dopaminergic agents, remain the only clinically pertinent pharmacological treatment proven effective and available for the large population of patients with Parkinson's disease. The challenge for the pharmaceutical industry is to develop disease-modifying drugs which could arrest, delay or at least oppose the progression of the specific pathogenic processes underlying Parkinson's disease. The purpose of this review, based on recent biological and genetic data to be validated with appropriate animal models, was to re-examine the putative neuroprotective agents in Parkinson's disease and discuss the development of new strategies with the ultimate goal of demonstrating neurocytoprotective activity in this neurodegenerative disease. Since guidelines for research on neurocytoprotective drugs remain to be written, innovation will be the key to success of future clinical trials. It is reasonable to expect that future advances in our understanding of the pathogenic processes of Parkinson's disease will open the way to new perspectives for the treatment of other neurodegenerative diseases.

Pharmacokinetic optimisation in the treatment of Parkinson's disease : an update

Pharmacotherapy for Parkinson's disease is focused on dopaminergic drugs, mainly the dopamine precursor levodopa and dopamine receptor agonists. The elimination half-life (t(1/2)) of levodopa from plasma (in combination with a decarboxylase inhibitor) of about 1.5 hours becomes more influential as the disease progresses. The long-duration of response to levodopa, which is evident in early Parkinson's disease, diminishes and after a few years of treatment motor performance is closely correlated to the fluctuating plasma concentrations of levodopa. Absorption of levodopa in the proximal small intestine depends on gastric emptying, which is erratic and may be slowed in Parkinson's disease. The effects of levodopa on motor function are dependent on gastric emptying in patients in the advanced stages of disease. The current treatment concept is continuous dopaminergic stimulation (CDS). Sustained-release formulations of levodopa may provide more stable plasma concentrations. Oral liquid formulations shorten the time to reach peak concentration and onset of effect but do not affect plasma levodopa variability. The t(1/2) of levodopa can be prolonged by adding a catechol-O-methyltransferase inhibitor (entacapone or tolcapone), which may reduce fluctuations in plasma concentrations, although both peak and trough concentrations are increased with frequent administration. Intravenous and enteral (duodenal/jejunal) infusions of levodopa yield stable plasma levodopa concentrations and motor performance. Enteral infusion is feasible on a long-term basis in patients with severe fluctuations. Among the dopamine receptor agonists the ergot derivatives bromocriptine, cabergoline, dihydroergocryptine and pergolide, and the non-ergot derivatives piribedil, pramipexole and ropinirole, have longer t(1/2) compared with levodopa. Thus, they stimulate dopamine receptors in a less pulsatile manner, yet pharmacokinetic studies of repeated doses of dopamine receptor agonists are few. Optimisation of these drugs is often performed with standardised titration schedules. Apomorphine and lisuride have short t(1/2) and are suitable for subcutaneous infusion, with results similar to those of levodopa infusion. Transdermal administration of dopamine receptor agonists such as rotigotine might be an alternative in the future. In general, initial dopamine receptor agonist monotherapy is associated with poorer motor performance and lower incidence of motor complications compared with levodopa. Buccal administration of the monoamine oxidase-B inhibitor selegiline (deprenyl) provides better absorption and less formation of metabolites compared with standard tablets. To conclude, several new drugs, formulations and routes of administration have been introduced in the treatment of Parkinson's disease during the last decade, mainly with CDS as the aim. CDS can be approached by optimising the use of dopaminergic drugs based on pharmacokinetic data.

Does levodopa slow or hasten the rate of progression of Parkinson's disease?

Levodopa therapy, as originally established by George Cotzias [2, 3], is the most powerful treatment for Parkinson's disease (PD). Levodopa's toxicity to neurons in vitro has raised concerns if it might hasten the progression of PD, although in vivo animal studies suggest it may be neuroprotective.

OBJECTIVE

To discuss the results of the ELLDOPA trial that was carried out to determine if levodopa therapy influences the rate of progression of Parkinson's disease (PD).

DESIGN

ELLDOPA was a multicenter, parallel-group, double-blind, dosage-ranging, randomized, controlled clinical trial.

SETTING

Academic movement disorders clinics at 38 sites in the United States and Canada.

PATIENTS

Three hundred and sixty-one patients with early PD of less than 2 years' duration who did not require symptomatic therapy.

INTERVENTIONS

Subjects were randomly assigned to one of four treatment groups: carbidopa/levodopa 12.5/50 mg t. i. d. (N=92), 25/100 mg t. i. d. (N=88), 50/200 mg t. i. d. (N=91), or matching placebo (N=90). The dosage was gradually escalated over 9 weeks and then maintained until Week 40, at which time active treatment was withdrawn over 3 days. After 2 weeks without active treatment (Week 42), a final assessment of PD severity was obtained.

OUTCOME MEASURES

The prespecified primary clinical outcome was the change in the total Unified Parkinson's Disease Rating Scale (UPDRS) between baseline and Week 42, comparing the four treatment groups. The primary neuroimaging component of the study in a subgroup of 142 subjects was the percent change in striatal (123)iodine 2-beta-carboxymethoxy-3-beta-(4-iodophe nyl)tropane (beta-CIT) uptake between baseline and Week 40 visits. The neuroimaging substudy utilized single photon emission computed tomography (SPECT) of the dopamine transporter.

RESULTS

All dosages of levodopa exerted clinical benefit compared to placebo on the UPDRS scores throughout the study, including 2 weeks after discontinuing levodopa. The UPDRS scores at Week 42 failed to reach the level encountered in the placebo group (change of 7.8+/-9.0, 1.9+/-6.0, 1.9+/-6.9, and -1.4+/-7.8, for placebo, 150 mg/day, 300 mg/ day, and 600 mg/day, respectively, p<0.0001). Nausea (p=0.001) and dyskinesias (p=0.0001) were more common in the levodopa groups, especially with the higher dosages. Freezing appeared around the same time, but was more common in the placebo (14 %) and 150 mg/day group (10 %). The percent decline of beta-CIT uptake in the striatum was significantly more pronounced in the levodopa groups than the placebo group (-7.2%, -4%, -6%, and -1.4% in 600 mg/day, 300 mg/day, 150 mg/day, and placebo, respectively; p=0.035).

CONCLUSIONS

The clinical outcomes not only indicate that levodopa is effective in a dose-dependent manner in overcoming the signs and symptoms of PD, they also support the concept that the drug does not hasten the disease progression, but rather may slow down the rate of the disease. The clinical study failed to demonstrate any evidence of levodopa worsening early PD. However, the beta-CIT SPECT substudy indicates the opposite effect, namely that levodopa causes a more rapid decline in the integrity of the dopamine transporter located in the nigrostriatal nerve terminals in the striatum. These contradictory findings warrant further investigation into the effect of levodopa on PD. OTHER OBSERVATIONS: The ELLDOPA study was the first levodopa dose-response study ever conducted. It showed that dose is a factor in the cause of producing motor complications of dyskinesias and wearing-off, and that these can develop as early as 5 to 6 months. On the other hand, freezing of gait could be delayed or its occurrence reduced by high dosage levodopa, compared to placebo or low-dose levodopa. Withdrawal of levodopa over a 3-day step-down can be safely carried out without inducing the neuroleptic-like syndrome. The UPDRS was shown to be a reliable linear marker for disease progression. The ELLDOPA study also called into question the interpretation of beta-CIT SPECT in the presence of dopaminergic agents. Neuroimaging in ELLDOPA also showed that some people diagnosed with early PD do not have a dopaminergic deficit, calling into question how difficult the correct diagnosis may be in people with early symptoms of PD.

Levodopa in the treatment of Parkinson's disease

Levodopa is the most efficacious drug to treat the symptoms of Parkinson's disease (PD) and is widely considered the "gold standard" by which to compare other therapies, including surgical therapy. Response to levodopa is one of the criteria for the clinical diagnosis of PD. A major limiting factor in levodopa therapy is the development of motor complications, namely dyskinesias and motor fluctuations. The ELLDOPA study was designed to determine if levodopa affected the progression of PD. This double-blind randomized study showed that the subjects treated with levodopa for 40 weeks had less severe parkinsonism than the placebo treated subjects even after a 2-week washout of medications, with the highest dose group showing the greatest benefit. Thus, levodopa may actually have neuroprotective value, but the result was not conclusive of slowing disease progression, because the same result could have arisen from a very long-lasting symptomatic benefit of levodopa.

A new look at levodopa based on the ELLDOPA study

Levodopa has been the gold standard for Parkinson's disease (PD) therapy since it was successfully introduced in 1967. But in the years since then, after recognizing that levodopa often leads to the motor complications of wearing-off and dyskinesias, there have been debates among clinicians as to when levodopa therapy should be started. Delaying therapy was advocated for the purpose of delaying the development of these motor complications. This became more popular as the dopamine agonists became available. Although less potent than levodopa in ameliorating the symptoms of PD, they were much less likely to produce the unwanted motor complications, even though they had their own adverse effects. When it was recognized that dopamine, itself, might be a factor leading to the death of dopaminergic neurons through its contributing to the formation of oxyradicals, a new concern arose, namely that levodopa, through its conversion to brain dopamine, might add to the existing oxidative stress and possibly enhance neurodegeneration of dopaminergic neurons. Though widely debated and without definite evidence, this possibility was sufficient to make some clinicians have further reason to delay the start of levodopa therapy. The ELLDOPA study was created to test this hypothesis. The clinical component of the study failed to find an enhancement of PD symptoms after levodopa was withdrawn following 40 weeks of levodopa therapy. Rather, the clinical results indicated that the symptoms had progressed much less than placebo, and in a dose-response manner. This suggests that levodopa may actually have neuroprotective properties. The uncertainty that a 2-week withdrawal of levodopa may not have entirely eliminated its symptomatic benefit and the discordant results of the neuroimaging component of the ELLDOPA study have created even more uncertainty that levodopa is neuroprotective. A survey of neurologists who treat PD patients showed that the vast majority of these clinicians do not believe levodopa is neuroprotective, and they remain concerned about the drug's likelihood of inducing motor complications. Thus, the ELLDOPA study failed to change the treating pattern of PD, and the clinicians require more convincing evidence of either neuroprotection or neurotoxicity of levodopa before they would alter their treatment approach.

Effect of a selective glutamate antagonist on l-dopa-induced dyskinesias in drug-naive parkinsonian monkeys

Alterations of striatal glutamate receptors are believed to be responsible, at least in part, for the pathogenesis of L-dopa-induced dyskinesias (LID). To evaluate whether co-administration of CI-1041, a novel NMDA receptor antagonist selective for the NR1A/NR2B subtype, with L-dopa might prevent the appearance of this side effect, eight de novo parkinsonian monkeys were treated chronically orally with either L-dopa alone or L-dopa plus CI-1041 (n= 4 for each group). After 4 weeks of treatment with L-dopa alone, all four animals developed moderate dyskinesias either choreic or dystonic in nature. CI-1041 co-treatment completely prevented the induction of dyskinesias in three animals and only one monkey developed mild dyskinesias at the end of the fourth week of treatment in the L-dopa + CI-1041 group. The magnitude and duration of the antiparkinsonian action of L-dopa was similar in both groups. These results suggest that selective NMDA receptor antagonism may be interesting for managing LID in Parkinson's disease patients.

Parkinson's disease and anaesthesia

Parkinson's disease is an increasingly common disease of elderly patients who present a particular anaesthetic challenge. This review explores the epidemiology, aetiology, pathogenesis, and pathophysiology of the condition, particularly the possible role of genetic factors. The clinical features are described in detail and recent advances in medical management are highlighted. Controversies surrounding the use of the newer drugs and possible advances in neurosurgical interventions are discussed. Particular anaesthetic problems in patients with Parkinson's disease are respiratory, cardiovascular, and neurological. Potential drug interactions are described and recommendations are made about suitable anaesthetic techniques.

Effect of levodopa on orthostatic and postprandial hypotension in elderly Parkinsonian patients

BACKGROUND

This study describes orthostatic and postprandial hypotension in elderly Parkinsonian patients and evaluates the effect of levodopa therapy on orthostatic and postprandial hypotension in these patients.

METHODS

Seventeen elderly patients with a clinical diagnosis of Parkinson's disease or Parkinsonism based on the U.K. Parkinson's Disease Society Brain Bank criteria (age range, 66-84 years) participated in the study. Blood pressure was continuously monitored during standardized standing and meal tests, after starting 125-mg b.i.d. doses of levodopa/benserazide (Madopar) or placebo, in a double-blind, randomized, cross-over design. Seventeen age- and sex-matched healthy subjects served as controls.

RESULTS

Orthostatic hypotension was infrequently found in Parkinsonian patients (13%) and healthy subjects (6%; p =.58, between groups), whereas postprandial hypotension was more frequent in Parkinsonian patients (82%) than in healthy subjects (41%; p <.05, between groups). Doses of levodopa/benserazide, administered 2 times per day, did not result in significantly larger blood pressure decreases after standing or eating, or in higher frequencies of orthostatic or postprandial hypotension in the Parkinsonian group. Postprandial hypotension was related to disease severity (r = -.56, p <.05).

CONCLUSIONS

Postprandial hypotension, but not orthostatic hypotension, was more common in elderly Parkinsonian patients than in healthy subjects. Therapy with 125-mg b.i.d. doses of levodopa/benserazide did not significantly aggravate orthostatic or postprandial hypotension.

Parkinson's Disease: Initial Treatment with Levodopa or Dopamine Agonists

The question of whether to use levodopa (LD) or dopamine agonists as initial therapy in Parkinson's disease has been a controversy for nearly 20 years. There are several issues relating to this treatment regimen that may effect ones decision. Review of them results in the following conclusions: LD does not cause the onset of motor fluctuations and dyskinesia; it probably relates to disease progression. Tolerance does not develop with long-term LD therapy. LD is not toxic. LD decreases mortality in Parkinson's disease. Motor fluctuations can occur with dopamine-agonist monotherapy, but the actual frequency is as yet unknown. Dopamine agonists are not neuroprotective. Clinical trials have indicated that LD remains the most potent symptomatic therapeutic agent available. Dopamine agonists do provide some symptomatic relief when used alone in early Parkinson's disease. Standard preparations of LD have the same effect on early disease as controlled release preparations. Dopamine agonists cause less dyskinesia and fluctuations. These conclusions indicate that both drugs are effective symptomatic agents with their own positive and negative aspects. There is no incorrect choice. It is reasonable to start young onset patients (younger than 50 years of age) with an agonist, because they seem to be more prone to develop motor fluctuations and dyskinesia. However, if employment is in jeopardy then LD may be needed. Because agonists cause more hallucinations, freezing, and somnolence, problems of particular relevance to the elderly (older than 70 years), then LD would be the best agent for older onset patients. In general, but particularly for those falling in between these age groups, treatment should be individualized. In this time of cost effectiveness, LD remains the least expensive of these agents.

Long-term mortality results of the randomized controlled study comparing bromocriptine to which levodopa was later added with levodopa alone in previously untreated patients with Parkinson's disease

The present paper compares, in terms of mortality, two treatment regimens for Parkinson's disease (PD), i.e., bromocriptine later combined with levodopa versus levodopa only. Between 1982 and 1989, 60 PD patients (29 treated with levodopa alone [group D] and 31 receiving first bromocriptine followed by an association of bromocriptine + levodopa [group B/D]) were recruited. Data were updated in January 2000. Survival functions were estimated using Kaplan Meier product-limit method and comparison between the two groups with the log-rank test. Mortality was also compared with that of the general French population using standardized mortality ratios (SMRs). The mean duration of follow-up was 10.3 +/- 3.0 years. Seventeen patients died during the follow-up: nine in the group B/D and eight in the group D. The probability of survival at 10 years was 79.0% [95% confidence interval [CI]: 71.4-86.6] in group B/D and 72.9% [95% CI: 63.3-82.6] in group D. In comparison with the general French population, SMRs were not statistically different from 1, in the whole sample of PD patients (1.21, 95 % CI [0.71-1.95]), in group D (0.98 [0.42-1.93]), or in group B/D (1.53 [0.70-2.92]). In this population, we were unable to find any favourable effect of an early use of bromocriptine on mortality in PD in comparison with levodopa alone.

Health-related quality of life and healthcare utilisation in patients with Parkinson's disease: impact of motor fluctuations and dyskinesias

Idiopathic Parkinson's disease (PD) is a common chronic progressive neuro-degenerative disorder associated with the progressive loss of dopaminergic neurons in the substantia nigra. The natural course of the disease may lead to severe disability despite a variety of pharmacological and surgical treatment options. Levodopa is still the most effective symptomatic treatment for PD; however, long term use can cause a number of adverse effects including motor complications, nausea and vomiting, postural hypotension and changes in mental status. The onset of motor complications marks a crucial point in the management of PD. They may present as changes between akinetic and mobile phases (motor fluctuations) or as abnormal involuntary movements (dyskinesias). After levodopa treatment for 3 to 5 years, motor complications occur in approximately 50% of patients, and after 10 years in >80% of patients. Treatment options have recently expanded as new drugs have been licensed and surgical procedures refined. Patients with motor complications present a demanding task in disease management, and often multiple drugs and high dosages are necessary to achieve only suboptimal control, resulting in increased healthcare utilisation. Costs increase considerably in patients with motor fluctuations and dyskinesias compared with patients without these symptoms. In a French study, 6-month direct medical costs per patient increased from 1648 euros (EUR) to EUR3028 in patients without and with motor fluctuations, respectively. In a recent French study a significant difference in monthly direct medical costs was found in patients with and without dyskinesias (EUR560 vs 170). Unfortunately, no data are available on the effect of motor complications on indirect costs. Several studies have shown that health-related quality of life (HR-QOL) is reduced when motor fluctuations occur. This may also be true of dyskinesias, but because of the limited number of studies a definite conclusion is not yet possible. Recently, surgical treatment options have been used to deal with advanced PD and late stage complications. Although their effect on motor complications and HR-QOL is well documented, they result in increased costs (total medical cost: EUR28920) compared with drug treatment alone and are increasingly restricted by healthcare providers. The purpose of this article is to review the available data from pharmacotherapeutic. surgical and economic studies on HR-QOL and healthcare expenditure in patients with PD, with a major focus on the impact of motor fluctuations and dyskinesias.

Dyskinesias and motor fluctuations in Parkinson's disease. A community-based study

We investigated the prevalence of dyskinesias and motor fluctuations, and the factors determining their occurrence, in a community-based population of patients with Parkinson's disease. Among 124 patients with Parkinson's disease, 87 (70%) had received a levodopa preparation. Among these 87 patients, 28% were experiencing treatment-induced dyskinesias and 40% response fluctuations. The prevalence of motor fluctuations was best predicted by disease duration and dose of levodopa, whereas dyskinesias could be best predicted by duration of treatment. Patients with a shorter time from symptom onset to initiation of levodopa and younger patients had developed motor complications earlier, and patients who had started treatment with a dopamine agonist had developed these treatment complications later. Although a satisfactory response to medication was associated with higher rates of motor complications, poor or moderate response was associated with lower quality of life in patients with a disease duration of </=5 years or >/=10 years. We conclude that motor fluctuations are most strongly related to disease duration and dose of levodopa, and dyskinesias to duration of levodopa treatment. However, poorer quality of life associated with inadequate dosage of levodopa may be the price for a low rate of motor complications in patients with Parkinson's disease.

Dopamine agonists: the treatment for Parkinson's disease in the XXI century?

Levodopa combined with a peripheral dopa-decarboxylase inhibitor (DCI) has been considered the therapy of choice for Parkinson's disease (PD). Levodopa is nearly always effective, but has a high incidence of adverse effects with long term use, including response fluctuations (on/off phenomena) and dyskinesias. Dopaminergic agonists, acting directly at the receptor level, would be able to decrease the incidence of these motor complications.In progressive neurodegenerative diseases, such as PD, modification of the rate of disease progression (often referred to as neuroprotection) is currently a highly debated topic. Increased oxidative stress is thought to be involved in nigral cell death, that is characteristic of PD. This oxidative stress may be further exacerbated by levodopa therapy. These mechanisms have been proven in vitro and animal models, but it's relevance in humans remains speculative.Based on the considerations above, the emerging therapeutic strategies for PD advocate early use of dopamine agonists in the treatment of PD. A number of recent well-controlled studies have proven the efficacy of dopamine agonists used as monotherapy. Moreover, as predicted by animal studies, on the long term, dopaminergic agonists induce significantly less motor complications than levodopa.In the last 2years, three new dopamine agonists have been launched, including ropinirole, pramipexole and cabergoline. These new agonists have been added, as therapeutical options to well-established drugs, like pergolide, bromocriptine or talipexole. The recently launched compounds have proven efficacy in monotherapy and as adjunctive therapy to levodopa. Unfortunately, only a very limited amount of comparative data among the different agonists is available. Pergolide has proven to be a superior drug to bromocriptine as adjunctive therapy to levodopa in a significant number of studies and is considered the gold standard dopamine agonist. Nevertheless, none of the recently launched compounds has compared itself against pergolide.A comparison of monotherapy trials is difficult, because of differences in design and populations. In a recently completed trial pergolide was statistically significantly better than placebo in all the efficacy parameters tested, with 57% of pergolide treated patients improving over 30% in the motor section of the UPDRS, as compared to 17% in the placebo arm. Interestingly, these results were obtained in the absence of any other antiparkinsonian drug during the trial. Recent monotherapy trials done with ropinirole and pramipexole achieved also significant improvements as monotherapy, but in these cases selegeline, a drug that causes a symptomatic improvement in PD, was allowed as co-medications during the trial. Not all trials used the same efficacy measures, i.e. monotherapy trials with pergolide and ropinirole used a "responder" based analysis (responder were all patients that improved 30% or more on the motor section of UPDRS), as well as a baseline to endpoint improvement in motor scores. Pramipexole monotherapy trials used only the latter approach, which is clinically less powerful than a responder analysis.Even with the difficulties mentioned above, all the recent trials with dopamine agonists have proven that these drugs are a useful symptomatic long term treatment for PD with or without levodopa and that the early use of dopamine agonists reduces the incidence of motor complications as compared to levodopa.