Increased risk of somnolence with the new dopamine agonists in patients with Parkinson's disease: a meta-analysis of randomised controlled trials

Sleep disorders and Parkinson's disease: is there a right direction?

In the last years, the hypothesis of a close relationship between sleep disorders (SDs) and Parkinson's disease (PD) has significantly strengthened. Whether this association is causal has been also highlighted by recent evidence demonstrating a neurobiological link between SDs and PD. Thus, the question is not whether these two chronic conditions are mutually connected, but rather how and when this relationship is expressed. Supporting this, not all SDs manifest with the same temporal sequence in PD patients. Indeed, SDs can precede or occur concomitantly with the onset of the clinical manifestation of PD. This review discusses the existing literature, putting under a magnifying glass the timing of occurrence of SDs in PD-neurodegeneration. Based on this, here, we propose two possible directions for studying the SDs-PD relationship: the first direction, from SDs to PD, considers SDs as potential biomarker/precursor of future PD-neurodegeneration; the second direction, from PD to SDs, considers SDs as concomitant symptoms in manifest PD, mainly related to primary PD-neuropathology and/or parkinsonian drugs. Furthermore, for each direction, we questioned SDs-PD relationship in terms of risk factors, neuronal circuits/mechanisms, and impact on the clinical phenotype and disease progression. Future research is needed to investigate whether targeting sleep may be the winning strategy to treat PD, in the context of a personalized precision medicine.

An overview of the effects of levodopa and dopaminergic agonists on sleep disorders in Parkinson's disease

Sleep disorders are among the most common nonmotor symptoms in Parkinson's disease and are associated with reduced cognition and health-related quality of life. Disturbed sleep can often present in the prodromal or early stages of this neurodegenerative disease, rendering it crucial to manage and treat these symptoms. Levodopa and dopaminergic agonists are frequently prescribed to treat motor symptoms in Parkinson's disease, and there is increasing interest in how these pharmacological agents affect sleep and their effect on concomitant sleep disturbances and disorders. In this review, we discuss the role of dopamine in regulating the sleep-wake state and the impact of neurodegeneration on sleep. We provide an overview of the effects of levodopa and dopaminergic agonists on sleep architecture, insomnia, excessive daytime sleepiness, sleep-disordered breathing, rapid eye movement sleep behavior disorder, and restless legs syndrome in Parkinson's disease. Levodopa and dopaminergic drugs may have different effects, beneficial or adverse, depending on dosing, method of administration, and differential effects on the different dopamine receptors. Future research in this area should focus on elucidating the specific mechanisms by which these drugs affect sleep in order to better understand the pathophysiology of sleep disorders in Parkinson's disease and aid in developing suitable therapies and treatment regimens.

CITATION

Scanga A, Lafontaine A-L, Kaminska M. An overview of the effects of levodopa and dopaminergic agonists on sleep disorders in Parkinson's disease. J Clin Sleep Med. 2023;19(6):1133-1144.

Excessive Daytime Sleepiness in Parkinson's Disease

Excessive daytime sleepiness (EDS) is one of the most common sleep disorders in Parkinson's disease (PD). It has attracted much attention due to high morbidity, poor quality of life, increased risk for accidents, obscure mechanisms, comorbidity with PD and limited therapeutic approaches. In this review, we summarize the current literature on epidemiology of EDS in PD to address the discrepancy between subjective and objective measures and clarify the reason for the inconsistent prevalence in previous studies. Besides, we focus on the effects of commonly used antiparkinsonian drugs on EDS and related pharmacological mechanisms to provide evidence for rational clinical medication in sleepy PD patients. More importantly, degeneration of wake-promoting nuclei owing to primary neurodegenerative process of PD is the underlying pathogenesis of EDS. Accordingly, altered wake-promoting nerve nuclei and neurotransmitter systems in PD patients are highlighted to providing clues for identifying EDS-causing targets in the sleep and wake cycles. Future mechanistic studies toward this direction will hopefully advance the development of novel and specific interventions for EDS in PD patients.

Meta-analysis of the adverse events associated with extended-release versus standard immediate-release pramipexole in Parkinson disease

BACKGROUND

In order to increase treatment choices for patients with Parkinson disease (PD), we performed a retrospective assessment of adverse events associated with a novel once-daily extended-release (ER) formulation versus the standard immediate-release (IR) of the nonergolinic dopamine agonist, pramipexole.

METHODS

The PubMed and Embase databases, as well as the foreign language medical information resource retrieval platform were searched from 2007 to 2017. The relative risks (RR) of various adverse events with 95% confidence intervals (95% CIs) were generated. The Modified Jadad score (MJs) was used to assess the quality of individual studies. Funnel plots were used to evaluate publication bias.

RESULTS

Three randomized controlled trials involving 1021 patients were included in this meta-analysis. We evaluated common adverse events associated with pramipexole in the gastrointestinal and nervous systems. These included the typical gastrointestinal symptom of nausea (RR = 0.96, 95% CI: 0.72-1.28; P = .80 > .05) and nervous system symptoms of somnolence (RR = 1.16, 95% CI: 0.95-1.43; P = .14 > .05), dizziness (RR = 1.11, 95% CI: 0.80-1.54; P = .54 > .05), and dyskinesia (RR = 0.87, 95% CI: 0.47-1.60; P = .66 > .05).

CONCLUSION

Patients with PD treated with 2 different pramipexole formulations (ER and IR) had similar incidences of common adverse events.

Sleepiness and Depression in Parkinson's Disease Patients Treated with Ropinirole and Levodopa

Objective

We aimed to investigate the effect of ropinirole on excessive daytime sleepiness (EDS) and depression in Parkinson’s disease (PD) with a large population.

Methods

We conducted a cross-sectional observational study at nine hospitals in Korea between April 24, 2013, and April 22, 2015. We analyzed the demographic and clinical features, other medical history, history of antiparkinsonian medication within 6 months, Hoehn and Yahr stage (HY stage), Unified Parkinson’s Disease Rating Scale (UPDRS) part II and III, Epworth Sleepiness Scale (ESS), and 30-item Geriatric Depression Scale (GDS-30).

Results

Four-hundred-thirteen patients with PD (mean age: 65.2 ± 9.0 years; men: 227 patients) were analyzed. Multivariate logistic regression analysis showed that age at examination, UPDRS II, and GDS-30 were independent risk factors for EDS and that sex, UPDRS II, and ESS were independent risk factors for depression.

Conclusion

Our large group study did not find any significant associations of ropinirole with EDS and depression in Korean PD patients.

Dopamine Agonists: Time Pattern of Adverse Effects Reporting in Australia

BACKGROUND

In Australia, there is voluntary reporting of suspected adverse events (AEs) of therapeutic medicines. Some dopamine agonists (DAs) have serious AEs.

OBJECTIVE

We aimed to explore the pattern of DA AE reporting over two decades.

METHODS

We analysed AE case line listings obtained from the Australian Committee on the Safety of Medicines (ACSOM) for bromocriptine, cabergoline, pergolide, pramipexole and ropinirole, and related these to drug utilisation data (1992-2012). We noted the AE nature, frequency, onset, novelty, severity and outcome.

RESULTS

The 220 suspected AEs fell into five categories: (i) syncopal/pre-syncopal, (ii) fibrotic, (iii) psychotic, (iv) obsessive-compulsive behaviours (OCB) and (v) increased sleep. There were differential lag times between initial individual drug registration and reporting of suspected AEs, with a lag of at least one year for fibrotic reactions and OCB compared to more contemporaneous reporting of other AEs. Consistent with the published literature, ACSOM data showed that ergot DAs share fibrotic reactions as a class AE, whereas symptomatic hypotensive reactions, psychosis and OCB occurred in both ergot and non-ergot DAs, cabergoline and pramipexole, respectively. Reports of syncopal and pre-syncopal reactions seemed to diminish as ergot-based DA use declined. Levodopa was taken simultaneously with DAs in 87 instances. Of those treated, 92 % were 50 years or older. Parkinson's disease accounted for 89 % of use (119 reports).

CONCLUSIONS

Exploring the temporal relationship between post-marketing AE reporting and utilisation data, as exemplified by DAs, can be a valuable pharmacovigilance tool to encourage targeted adverse event monitoring and reporting.

Nonmotor symptoms of Parkinson’s disease

Nonmotor symptoms occur commonly in Parkinson's disease (PD) patients and are frequently under-recognized and undertreated. Symptoms include sleep abnormalities, fatigue, autonomic disturbances, mood disorders and cognitive dysfunction. Early recognition and treatment of nonmotor symptoms in PD is critical to providing optimal management. A new screening questionnaire and the revised Unified PD Rating Scale should assist healthcare providers to better identify and evaluate these symptoms. This article reviews the identification and treatment of nonmotor symptoms in PD.

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.

Systematic review of methods used in meta-analyses where a primary outcome is an adverse or unintended event

BACKGROUND

Adverse consequences of medical interventions are a source of concern, but clinical trials may lack power to detect elevated rates of such events, while observational studies have inherent limitations. Meta-analysis allows the combination of individual studies, which can increase power and provide stronger evidence relating to adverse events. However, meta-analysis of adverse events has associated methodological challenges. The aim of this study was to systematically identify and review the methodology used in meta-analyses where a primary outcome is an adverse or unintended event, following a therapeutic intervention.

METHODS

Using a collection of reviews identified previously, 166 references including a meta-analysis were selected for review. At least one of the primary outcomes in each review was an adverse or unintended event. The nature of the intervention, source of funding, number of individual meta-analyses performed, number of primary studies included in the review, and use of meta-analytic methods were all recorded. Specific areas of interest relating to the methods used included the choice of outcome metric, methods of dealing with sparse events, heterogeneity, publication bias and use of individual patient data.

RESULTS

The 166 included reviews were published between 1994 and 2006. Interventions included drugs and surgery among other interventions. Many of the references being reviewed included multiple meta-analyses with 44.6% (74/166) including more than ten. Randomised trials only were included in 42.2% of meta-analyses (70/166), observational studies only in 33.7% (56/166) and a mix of observational studies and trials in 15.7% (26/166). Sparse data, in the form of zero events in one or both arms where the outcome was a count of events, was found in 64 reviews of two-arm studies, of which 41 (64.1%) had zero events in both arms.

CONCLUSIONS

Meta-analyses of adverse events data are common and useful in terms of increasing the power to detect an association with an intervention, especially when the events are infrequent. However, with regard to existing meta-analyses, a wide variety of different methods have been employed, often with no evident rationale for using a particular approach. More specifically, the approach to dealing with zero events varies, and guidelines on this issue would be desirable.

Pramipexole for the treatment of early Parkinson's disease

Pramipexole is a nonergolinic dopamine agonist, with high affinity for the D2 subfamily of dopamine receptors. Pramipexole is efficacious for the symptomatic treatment of early Parkinson's Disease (PD) and its early use, before that of levodopa can delay the emergence of levodopa-related motor complication. Dosage should be increased gradually from a starting dose of 0.375 mg/day up to a maximum of 4.5 mg/day in equally divided doses taken three times per day with pramipexole immediate-release or equivalent daily dosages once-daily with pramipexole extended-release. Pramipexole can also improve depressive symptoms and possibly health-related quality of life in PD. Nonetheless, its use is not devoid of tolerability problems. While peripheral adverse drug reactions, such as nausea, vomiting or orthostatic hypotension, can be effectively treated and usually pose few problems to most patients, neuropsychiatric events can seriously limit the use of pramipexole in some cases. Indeed, excessive daytime somnolence, impulse-control disorders, hallucinations or delusions can severely affect patients, causing important personal or social handicap. Patients should be informed about the risk of such neuropsychiatric complications and their presence should be actively detected at each consultation. More effort will have to be put into further studying the risk-benefit ratio of pramipexole and other dopamine agonists in the treatment of early PD.

Effect of chronic kidney disease on excessive daytime sleepiness in Parkinson disease

BACKGROUND AND PURPOSES

Excessive daytime sleepiness (EDS) is a common sleep disorder in patients with Parkinson disease (PD). Non-ergot dopamine agonists increase the risk of unanticipated sleep episodes.

OBJECTIVE

  We aimed to assess the influence of renal function on EDS in patients with PD.

METHODS

Sixty-two patients treated with ropinirole or pramipexole were recruited for this study. We evaluated the historical and clinical characteristics including the motor symptom rating scales, Epworth Sleepiness Scale (ESS), and estimated glomerular filtration rate (eGFR). An ESS score of 10 or greater was defined as EDS. Participants with eGFR < 60 ml/min/1.73 m(2) were determined to have chronic kidney disease (CKD). Multiple logistic regression analysis was performed to determine the predictive factors of EDS.

RESULTS

Chronic kidney disease was found to be a significant predictive factor for EDS in all patients (P = 0.014). We observed a negative correlation between the severity of daytime sleepiness and renal function in patients treated with pramipexole alone (r(s) = -0.637, P < 0.001).

CONCLUSIONS

Chronic kidney disease may be a risk factor for EDS, especially in patients treated with pramipexole, which is directly excreted in the urine.

Dopamine receptor agonists for the treatment of early or advanced Parkinson's disease

Dopamine receptor agonists are indicated for the symptomatic treatment of early, moderate or advanced Parkinson's disease as well as for the reduction of levodopa-related motor complications. Ergolinic dopamine agonists, such as bromocriptine or pergolide, were initially developed and marketed, and then non-ergolinic dopamine agonists, such as pramipexole and ropinirole, were introduced, reducing the risk of drug-induced fibrotic reactions. Once-daily, controlled-release oral and transdermal formulations have been developed aiming at providing more stable 24-hour plasma drug concentrations and more convenient administration. A disease-modifying effect of dopamine agonists has not been demonstrated clinically. As with any other drug, dopamine agonists can also cause adverse drug reactions, which can be related or unrelated to dopaminergic hyperactivation. Dopaminergic reactions include nausea, hallucinations, confusion and orthostatic hypotension, among others, which were readily identified in pre-marketing clinical trials. During post-marketing surveillance, important adverse reactions were identified, such as daytime somnolence, impulse-control disorders and heart valve fibrosis. Other issues, including the efficacy of dopamine agonists for the treatment of non-motor symptoms, remain under evaluation.

Approaches to measuring the effects of wake-promoting drugs: a focus on cognitive function

OBJECTIVES

In clinical drug development, wakefulness and wake-promotion may be assessed by a large number of scales and questionnaires. Objective assessment of wakefulness is most commonly made using sleep latency/maintenance of wakefulness tests, polysomnography and/or behavioral measures. The purpose of the present review is to highlight the degree of overlap in the assessment of wakefulness and cognition, with consideration of assessment techniques and the underlying neurobiology of both concepts.

DESIGN

Reviews of four key areas were conducted: commonly used techniques in the assessment of wakefulness; neurobiology of sleep/wake and cognition; targets of wake promoting and/or cognition enhancing drugs; and ongoing clinical trials investigating wake promoting effects.

RESULTS

There is clear overlap between the assessment of wakefulness and cognition. There are common techniques which may be used to assess both concepts; aspects of the neurobiology of both concepts may be closely related; and wake-promoting drugs may have nootropic properties (and vice versa). Clinical trials of wake-promoting drugs often, though not routinely, assess aspects of cognition.

CONCLUSIONS

Routine and broad assessment of cognition in the development of wake-promoting drugs may reveal important nootropic effects, which are not secondary to alertness/wakefulness, whilst existing cognitive enhancers may have underexplored or unknown wake promoting properties.

Update on the use of pramipexole in the treatment of Parkinson's disease

Pramipexole is a non-ergot dopamine agonist shown to be efficacious in the treatment of Parkinson's disease (PD). This review addresses the literature concerning pramipexole's efficacy in treating motor and non-motor symptoms in PD, its impact on the development of dyskinesias and response fluctuations, the issue of neuroprotection, and the risk for developing adverse events such as increased somnolence, attacks of sudden onset of sleep, cardiac valvulopathy and impulse control disturbances.

Review of the therapeutic management of Parkinson's disease. Report of a joint task force of the European Federation of Neurological Societies and the Movement Disorder Society-European Section. Part I: early (uncomplicated) Parkinson's disease

The aim of the study was to provide evidence-based recommendations for the management of early (uncomplicated) Parkinson's disease (PD), based on a review of the literature. Uncomplicated PD refers to patients suffering from the classical motor syndrome of PD only, without treatment-induced motor complications and without neuropsychiatric or autonomic problems. MEDLINE, Cochrane Library and International Network of Agencies for Health Technology Assessment (INAHTA) database literature searches were conducted. National guidelines were requested from all European Federation of Neurological Societies (EFNS) societies. Non-European guidelines were searched for using MEDLINE. Part I of the guidelines deals with prevention of disease progression, symptomatic treatment of motor features (parkinsonism), and prevention of motor and neuropsychiatric complications of therapy. 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.

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.

Médicaments, maladie de Parkinson et syndromes parkinsoniens : actualités de pharmacovigilance

This paper reviews recent data on the pharmacovigilance of antiparkinsonian drugs and drugs inducing parkinsonian syndroms. Sudden sleep attacks were first described in 1999 with dopamine agonists. In fact, they can be induced by all the dopaminergic antiparkinsonian drugs. Favorising factors are duration of the disease, dose of dopaminergic drugs, daytime somnolence or dysautonomia. This adverse drug reaction can be serious leading, for example, to road accidents. Cardiac valvulopathies were more recently (end of 2002) described with pergolide. Thus, this dopamine agonist should now be prescribed as a last choice among dopamine agonists. Dopamine drugs (levodopa as well as dopamine agonists) can induce hypersexual behaviours or pathological gambling. Among the long list of drugs inducing parkinsonian syndroms, recent data suggest the involvement of serotoninergic antidepressants, valproic acid and trimetazidine. Finally, these data on pharmacovigilance allow to precise the physiological role of dopamine: beside its motor and psychic effects, dopamine is also involved in the sleep-arousal control. It is also an important mediator for pleasure, hedonic regulations and sexual behaviour. This review also underlines the major role of spontaneous reports to the pharmacovigilance systems to identify new adverse drug reactions.

Ropinirole in treatment-resistant depression: a 16-week pilot study

OBJECTIVE

The study aimed to assess the antidepressant efficacy and tolerability of adjunctive ropinirole in outpatients with treatment-resistant depression (TRD).

METHOD

The study sample consisted of patients with a major depressive episode (diagnosed according to DSM-IV criteria) and TRD. Ropinirole 0.25 to 1.5 mg daily was added to tricyclic antidepressants or selective serotonin reuptake inhibitors. We conducted assessments at baseline and at weeks 2, 4, 8, 12, and 16. We defined response as a 50% or greater reduction of the Montgomery-Asberg Depression Rating Scale (MADRS) total score plus a score of 1 ("very much improved") or 2 ("much improved") on the Clinical Global Impression of Improvement scale at endpoint. Tolerability was monitored with the Dosage Record Treatment Emergent Symptom Scale.

RESULTS

Seven patients had major depressive disorder, and 3 had bipolar II disorder. The mean maximum dose of ropinirole was 1.33 mg daily. Mean (SD) scores on the MADRS decreased from 29.6 (7.6) at baseline to 16.9 (12.1) at endpoint (P < 0.02). At endpoint, 4 of 10 (40%) patients were responders. Two patients discontinued ropinirole because of dizziness.

CONCLUSIONS

These pilot data suggest that, in selected cases of TRD, ropinirole augmentation of antidepressants is effective and relatively well tolerated.

Evidence-based medical review update: Pharmacological and surgical treatments of Parkinson's disease: 2001 to 2004

The objective of this study is to update a previous evidence-based medicine (EBM) review on Parkinson's disease (PD) treatments, adding January 2001 to January 2004 information. The Movement Disorder Society (MDS) Task Force prepared an EBM review of PD treatments covering data up to January 2001. The authors reviewed Level I (randomized clinical trials) reports of pharmacological and surgical interventions for PD, published as full articles in English (January 2001-January 2004). Inclusion criteria and ranking followed the original program and adhered to EBM methodology. For Efficacy Conclusions, treatments were designated Efficacious, Likely Efficacious, Non-Efficacious, or Insufficient Data. Four clinical indications were considered for each intervention: prevention of disease progression; treatment of Parkinsonism, as monotherapy and as adjuncts to levodopa where indicated; prevention of motor complications; treatment of motor complications. Twenty-seven new studies qualified for efficacy review, and others covered new safety issues. Apomorphine, piribedil, unilateral pallidotomy, and subthalamic nucleus stimulation moved upward in efficacy ratings. Rasagiline, was newly rated as Efficacious monotherapy for control of Parkinsonism. New Level I data moved human fetal nigral transplants, as performed to date, from Insufficient Data to Non- efficacious for the treatment of Parkinsonism, motor fluctuations, and dyskinesias. Selegiline was reassigned as Non-efficacious for the prevention of dyskinesias. Other designations did not change. In a field as active in clinical trials as PD, frequent updating of therapy-based reviews is essential. We consider a 3-year period a reasonable time frame for published updates and are working to establish a Web-based mechanism to update the report in an ongoing manner.

Quantifying adverse drug events : are systematic reviews the answer?

Quantifying adverse drug events (ADEs) is critical to clinicians, consumers and policy makers. Most ADE information comes from large clinical trials. Systematic reviews have become a popular tool in quantifying the efficacy of different therapeutic interventions and ADE data collected in randomised trials may be helpful in quantifying the risk associated with a specific pharmacological agent. However, clinicians who are interested in conducting systematic reviews of ADEs may face many challenges. These challenges are geared towards two main areas: poor quality of ADE reporting in randomised trials and poor indexing of ADEs in medical databases. In this review, we will discuss these challenges in detail using some examples from the literature. Where possible, we also discuss strategies that may overcome these problems. More rigourous standards of reporting ADEs in randomised trials, as well as better indexing of ADE terminology in medical databases, could one day make systematic reviews of ADEs a powerful tool for practising clinicians.

Parkinson's disease

Parkinson's disease is the most common serious movement disorder in the world, affecting about 1% of adults older than 60 years. The disease is attributed to selective loss of neurons in the substantia nigra, and its cause is enigmatic in most individuals. Symptoms of Parkinson's disease respond in varying degrees to drugs, and surgery offers hope for patients no longer adequately controlled in this manner. The high prevalence of the disease, and important advances in its management, mean that generalists need to have a working knowledge of this disorder. This Seminar covers the basics, from terminology to aspects of diagnosis, treatment, and pathogenesis.

Sleep attacks and dopamine agonists for Parkinson's disease: what is currently known?

The aetiology of sleep disturbances in patients with Parkinson's disease is multifactorial. Medications, the disease process and underlying sleep disorders may contribute to sleepiness in patients with the disease. Somnolence, excessive daytime sleepiness and sleep attacks appear to be more common in patients with Parkinson's disease who are treated with dopamine receptor agonists than in those who are treated with other antiparkinsonian agents, although virtually all dopaminergic antiparkinsonian medications may contribute to sleepiness. Somnolence caused by dopamine agonists may be dose related and occurs most frequently during the dose-escalation phase. Somnolence may also emerge or worsen after a period of time on a stable dose. Patients with Parkinson's disease and caregivers should be informed about the risk of sleepiness and sleep attacks associated with dopaminergic medications and the potential implications for driving safety.

Parkinson's disease and sleep

Sleep disorders are common in Parkinson's disease (PD), as almost two thirds of PD patients report them. From a clinical point of view, they can be classified into disorders of initiation and maintenance of sleep (DIMS), parasomnias, and excessive daytime sleepiness (EDS). Among the causes of DIMS are degenerative changes in the CNS affecting centers for sleep regulation, persistence into the night of daytime PD-related symptoms, concomitant medical or psychiatric disease, disruption of circadian rhythms, and effects of dopaminergic (and other) medication on sleep regulation. Parasomnias might further contribute to sleep disturbance, as they can be accompanied by motor desinhibition during REM sleep. Parasomnias can precede by several years the presence of daytime PD symptoms. EDS has been over the last years the focus of attention for both sleep and movement disorders specialists, due to the fact that it might predispose to traffic accidents. However, the so-called "sleep attacks" never occur without preexisting somnolence. Thus, a careful sleep history can be helpful to determine which patients are exposed to suffer them. Although EDS was initially attributed to the effects of dopaminergic medication, it seems likely that several disease-related factors might also play an important role. An adequate education of the PD patients in sleep hygiene measures and a skilled use of the medication seem necessary to prevent sleep disturbance.

Sleep attacks in Parkinson's disease induced by Entacapone, a COMT-inhibitor

We present a patient who suffered from sleep attacks after starting entacapone in addition to levodopa. Entacapone, a catechol-O-methyl transferase inhibitor, alters the pharmacokinetics of levodopa, leading to increase of levodopa concentration in plasma and brain. This mechanism is suspected to be involved in the pathophysiology of sleep attacks in this case.

Piribedil-induced sleep attacks in Parkinson's disease

'Sleep attacks', episodes of sudden onset of sleep without any prodromal symptoms, were initially described in patients with Parkinson's disease (PD) taking the newer dopamine agonists pramipexole and ropinirole. Piribedil, a nonergot agonist with both D2 and D3 agonist action, is an effective antiparkinsonian medication. However, there are very few reports of Piribedil-induced sleep attacks in PD. Among 50 PD patients seen at our Movement Disorder Clinic who had recently taken Piribedil, we identified three (6%) who satisfied the clinical description of sleep attacks. Here we provide details of the clinical characteristics of Piribedil-induced sleep attacks in these PD patients.

The management of patients with early Parkinson's disease

A major problem in the management of early Parkinson's disease is to choose the first medication to prescribe. This decision should rely on the level of available clinical evidence, largely based, at least for efficacy, on the results of randomised clinical trials. Safety and costs are also crucial to consider. Other factors like for example pathophysiological concepts, individual experience, marketing pressure, socio-economical environment, patients needs and expectations have, however, also their own influence. Levodopa is efficacious and cheap, but induces long-term motor complications. The early use of dopamine agonists is more and more frequently promoted, because large prospective L-dopa-controlled trials demonstrated that this strategy reduces the risk of such long-term complications. Integrating individual clinical expertise to the best available external clinical evidence (evidence-based medicine) is the best strategy in making decisions about the care of individual patients.

'Sleep attacks' or 'unintended sleep episodes' occur with dopamine agonists: is this a class effect?

Controversial reports of sudden onset 'sleep attacks' resulting in road traffic accidents have recently been reported in patients with Parkinson's disease (PD) taking the non-ergot dopamine D(2 )/D(3) receptor agonists pramipexole and ropinirole. These reports have generated considerable debate as the concept of 'sleep attacks' is disputed amongst sleep specialists and most believe that isolated 'sleep attacks' not preceded by warning on the background of chronic sleepiness or 'unintended sleepiness' do not exist. A series of case reports suggested that this phenomenon may not be exclusive to the non-ergot dopamine agonists such as pramipexole or ropinirole and indeed may occur with most dopaminergic agents. Recent evidence suggest that a 'sleepiness' or 'hypoactivity' reaction to dopaminergic therapy may be related to underlying dopamine deficiency of PD rather than a drug effect. In this report we provide the evidence for the phenomenon being a class effect attributable to all dopamine agonists currently employed in the management of PD. Controversy surrounding excessive daytime sleepiness (EDS) in PD and the use of the Epworth Sleepiness Scale (ESS) in relation to PD is also discussed. In spite of variable reports, EDS is recognised to be common in PD and is likely to be related to both the disease process and drug therapy. Studies using multiple sleep latency tests have also reported differing results in PD although a recent study indicated that a subset of 'sleepy' patients with PD may experience pathological somnolence with resultant detrimental consequence on daytime and cognitive functions. We recommend that the issue of 'sleepiness' or 'sleep attacks' in PD should be routinely checked in all patients with PD and indirectly assessed by using either the ESS or the recently introduced Parkinson's Disease Sleep Scale. Those with reported 'sleep attacks' or 'unintended sleep episodes' and excessive daytime sleepiness while taking dopamine agonists or dopaminergic agents such as levodopa should have a review of their medication, should not be driving a car on their own and some may merit formal sleep architecture studies. The latter may identify sleep disorders such as secondary narcolepsy which may benefit from the use of a wakefulness promoting agent.

Clinical pharmacokinetic and pharmacodynamic properties of drugs used in the treatment of Parkinson's disease

Current research in Parkinson's disease (PD) focuses on symptomatic therapy and neuroprotective interventions. Drugs that have been used for symptomatic therapy are levodopa, usually combined with a peripheral decarboxylase inhibitor, synthetic dopamine receptor agonists, centrally-acting antimuscarinic drugs, amantadine, monoamine oxidase-B (MAO-B) inhibitors and catechol-O-methyltransferase (COMT) inhibitors. Drugs for which there is at least some evidence for neuroprotective effect are certain dopamine agonists, amantadine and MAO-B inhibitors (selegiline). Levodopa remains the most effective drug for the treatment of PD. Several factors contribute to the complex clinical pharmacokinetics of levodopa: erratic absorption, short half-life, peripheral O-methylation and facilitated transport across the blood-brain barrier. In patients with response fluctuations to levodopa, the concentration-effect curve becomes steeper and shifts to the right compared with patients with stable response. Pharmacokinetic-pharmacodynamic modelling can affect decisions regarding therapeutic strategies. The dopamine agonists include ergot derivatives (bromocriptine, pergolide, lisuride and cabergoline), non-ergoline derivatives (pramipexole, ropinirole and piribedil) and apomorphine. Most dopamine agonists have their specific pharmacological profile. They are used in monotherapy and as an adjunct to levodopa in early and advanced PD. Few pharmacokinetic and pharmacodynamic data are available regarding centrally acting antimuscarinic drugs. They are characterised by rapid absorption after oral intake, large volume of distribution and low clearance relative to hepatic blood flow, with extensive metabolism. The mechanism of action of amantadine remains elusive. It is well absorbed and widely distributed. Since elimination is primarily by renal clearance, accumulation of the drug can occur in patients with renal dysfunction and dosage reduction must be envisaged. The COMT inhibitors entacapone and tolcapone dose-dependently inhibit the formation of the major metabolite of levodopa, 3-O-methyldopa, and improve the bioavailability and reduce the clearance of levodopa without significantly affecting its absorption. They are useful adjuncts to levodopa in patients with end-of-dose fluctuations. The MAO-B inhibitor selegiline may have a dual effect: reducing the catabolism of dopamine and limiting the formation of neurotoxic free radicals. The pharmacokinetics of selegiline are highly variable; it has low bioavailability and large volume of distribution. The oral clearance is many-fold higher than the hepatic blood flow and the drug is extensively metabolised into several metabolites, some of them being active. Despite the introduction of several new drugs to the antiparkinsonian armamentarium, no single best treatment exists for an individual patient with PD. Particularly in the advanced stage of the disease, treatment should be individually tailored.