Pergolide in the treatment of patients with early and advanced Parkinson's disease

Introduced on the market in 1989, pergolide, a D1/D2 dopamine receptor agonist, is still widely prescribed for the treatment of patients with early and advanced Parkinson's disease (PD). Initially, pergolide was introduced as an adjunct therapy to levodopa treatment in patients exhibiting fluctuating motor responses and dyskinesias. Results of recent randomized controlled clinical trials in de novo patients with PD show that pergolide is able to improve parkinsonian symptoms when used as monotherapy. Moreover, preliminary results of a long-term monotherapy study in early PD suggest that pergolide is as effective as levodopa, and that a significant delay in the time of the onset of levodopa-induced motor complications can be obtained. A number of randomized studies have shown that pergolide is more effective than bromocriptine as adjunct therapy to levodopa in patients with advanced PD; the greater benefit found with pergolide could be ascribed to its action on both D1 and D2 dopamine receptors. However, controlled comparative studies with new dopamine agonists, such as ropinirole, cabergoline, and pramipexole, have not been performed yet. Interestingly, few open studies in patients with complicated PD have shown that high doses of pergolide (> 6 mg/d) are able to improve motor fluctuations and dyskinesias through a dramatic reduction of levodopa dosage. The side-effect profile of pergolide is similar to that of other dopamine agonists, and complications such as sleep attack and serosal fibrosis have been rarely reported.     

Rationale for dopamine agonist use as monotherapy in Parkinson's disease

Dopamine agonists are increasingly being used in the initial treatment of patients with de-novo Parkinson's disease because they provide symptom relief and a low risk of the dyskinesia frequently associated with levodopa. Evidence is also mounting in preclinical models that dopamine agonists protect dopaminergic neurons from the toxic effects of oxidative stress and the by-products of dopamine and L-dopa metabolism. Ergot derivatives, such as pergolide, induce minor side-effects and provide significant and sustained improvements in motor function in patients with early Parkinson's disease. Dopamine agonists also appear to reduce the loss of functional dopamine transporters when used early in the disease course, and these factors combine to build a case for the use of dopamine agonists in early-stage Parkinson's disease.     

Valvular heart disease in Parkinson's disease treated with ergot derivative dopamine agonists.

Valvular heart disease, associated with ergot derivative dopamine agonists, has been reported in patients with Parkinson's disease (PD). There are few comparative studies on the frequency, severity, and dose dependency of valvular disease associated with ergot derivatives. We analyzed these factors in 58 PD patients who were taking ergot derivatives (22 were taking bromocriptine and 36 were taking pergolide) and compared them with 20 age-matched controls based on the two-dimensional echocardiographic findings. Aortic, mitral, and tricuspid valvular thicknesses, as well as tenting areas and tenting distance of the mitral valve were measured. We also assessed the correlation between the cumulative or daily doses of ergot derivatives and each valvular parameter. There was no significant increase in the frequency of valvulopathy in the PD patients taking bromocriptine or pergolide. We identified a positive correlation between the daily dose of pergolide and the tenting area of the mitral valve (r = 0.385; P = 0.020). However, other valvular parameters were not found to correlate with the age, disease duration, treatment duration, or dosage of medication. Our study failed to uncover definitive harmful effects of ergot derivative dopamine agonists on cardiac valves; this is considering the relatively lower daily doses than other reported cases. To establish a dosage dependency with valvulopathy, a more detailed study with higher doses of ergot derivatives for longer duration of treatment may be needed.     

Rotigotine for the treatment of Parkinson's disease

Dopaminergic therapies, including levodopa and dopamine agonists, are the mainstays of therapy in Parkinson's disease. With the exception of the injectable short-acting dopamine agonist apomorphine, there is no other widely available non-oral dopaminergic therapy. Rotigotine is a lipid-soluble, non-ergot, D3, D2, D1 dopamine receptor agonist that has demonstrated efficacy as an alternative therapeutic option in both early and advanced Parkinson's disease. More importantly, it is uniquely formulated as a transdermal patch delivery system allowing for continuous, once-daily administration and better patient compliance. Preclinical and clinical trials have shown rotigotine to be a well-tolerated and effective treatment for early-stage Parkinson's disease. Rotigotine has also shown promise as adjunctive therapy with levodopa for the treatment of advanced Parkinson's disease.     

Appropriate dosing of pergolide in monotherapy and adjunctive therapy in Parkinson's disease

Pergolide is one of the most well-tested and widely used dopamine agonists for the treatment of Parkinson's disease; however, there is worrying evidence that sub-therapeutic dosing of pergolide is widespread in clinical practice. Clinical studies in Caucasians suggest that a pergolide dose of 3 mg/day provides the optimal efficacy to tolerability ratio and that, in Japanese patients, a dose in excess of 2.25 mg/day may be ideal. Whether pergolide is used early in patients with de-novo Parkinson's disease or as adjunctive therapy later in the disease, in order to optimize its clinical efficacy, it is recommended that practitioners aim to achieve at least these doses, or higher ones, if the drug is well tolerated.     

Dopamine agonists, receptor selectivity and dyskinesia induction in Parkinson's disease

Levodopa and the dopamine agonists are effective symptomatic treatments for Parkinson's disease, and all patients receive at least one of these agents during their illness. Long-term use of levodopa is commonly associated with motor complications such as dyskinesia, and both the dosing frequency and total daily dose of levodopa determine the rate of onset and severity. Dopamine agonists have gained popularity as first-line monotherapy in Parkinson's disease, as they effectively reverse motor deficits and reduce the risk of motor complications. Long-acting dopamine agonists providing continuous, rather than pulsatile, dopaminergic stimulation appear able to avoid dyskinesia induction. Current treatments act predominantly on D2 receptors, but drugs acting on both the D1 and D2 receptor families may produce an additive motor response, although this remains to be proven in patients with Parkinson's disease. Most currently used dopamine agonists are selective for D2-like receptors, with only pergolide and apomorphine potentially interacting with D1 receptor populations.     

Parkinson's disease and sleep

There are many reasons for patients with idiopathic Parkinson's disease to develop sleep disorders and subsequent daytime sleepiness. Important causes are reduction of total sleep duration and sleep efficiency, and an increase in respiratory and motor arousals. This daytime sleepiness at first glance seems different from the "sleep attacks" which caused motot vehicle mishaps reported recently in persons taking pramipexole and ropinirole. There is, however, only little evidence that we deal with a new phenomenon in a new clinical situation, i. e. cataplexy-like attacks after high doses of new non-ergot dopamine-agonists. Until now there is no single case of a proven cataplexy on one hand, and older dopamine agonists like pergolide as well as L-Dopa + carbidopa have been reported to induce sudden onsets of sleep, too.     

Valvular heart disease in Parkinson's disease patients treated with dopamine agonists: a reader-blinded monocenter echocardiography study.

Fibrotic valvular heart disease (VHD) has been reported in association with ergot dopamine agonists (DAs), but the current database is insufficient regarding clinical relevance and comparison to data on non-ergot DAs. We evaluated the effects of four DAs (pergolide, cabergoline, ropinirole, pramipexole) on morphology and function of heart valves in patients with Parkinson's disease (PD) to determine the frequency and clinical relevance of DA-induced VHD. A total of 85 patients treated with ergot or non-ergot DAs and 38 age-matched controls were evaluated by transthoracic echocardiography. Valvular pathology was assessed by established criteria of valvular regurgitation and a VHD scoring system. Both grading systems revealed increased frequency of VHD in ergot DA patients compared to both non-ergot DA patients and controls with 22% of ergot DA patients having moderate VHD versus 3% of non-ergot DA patients and none of controls (P = 0.001). We did not find correlations of echocardiographic findings with duration/cumulative dose of treatment, age, or vascular risk factors. Our data suggest that ergot DAs are associated with higher prevalence of VHD compared to non-ergot DAs and controls. Standard echocardiography seems sufficient to detect VHD in PD patients treated with DAs.     

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.     

Neuroleptic malignant-like syndrome after rapid switch from bromocriptine to pergolide

Neuroleptic malignant-like syndrome (NMLS) occurred after rapid switch from bromocriptine to pergolide in a Parkinsonian patient. Although the underlying mechanisms are as yet obscure, we hypothesize that differences in dopamine receptor affinities between bromocriptine and pergolide may be involved. Long-term treatment with bromocriptine may thus have induced plastic changes in intracellular signal processing in the nigrostriatal system, which resulted in reduced dopaminergic efficacy of pergolide. We recommend vigilant outpatient supervision during performance of rapid switchover from one dopamine agonist to another in advanced Parkinson's disease or in subjects with predisposing factors for onset of a neuroleptic malignant syndrome.     

Dopamine agonists

Dopamine agonists provide an effective means of treating early, middle, and late stages of Parkinson's disease. This article outlines the advantages and disadvantages of dopamine agonists as compared with levodopa therapy. The features and costs of the four Food and Drug Administration-approved agonists (bromocriptine, pergolide, pramipexole, and ropinirole) and apomorphine, another agonist presently under investigation, are discussed.     

Dopamine agonists in Parkinson's disease

Dopamine agonists are established as effective drugs for the symptomatic treatment of Parkinson's disease (PD) throughout its course. As monotherapy, they produce effective control of motor symptoms and combine this with a low risk for motor complications. As an adjunct to levodopa, they improve motor control and limit the need for levodopa in those patients in whom this may be considered relevant. The non-ergot dopamine agonists in particular have a good safety profile, although as with other agonists, sedation, and cognitive and behavioral problems may be limiting in some patients. Pramipexole has shown benefit in improving depressive symptoms in PD. Ropinirole and pramipexole have both demonstrated a reduction in the rate of loss of nigrostriatal innervation as determined by imaging in PD patients, when compared with levodopa. Thus, dopamine agonists contribute to several dimensions of the management of PD and have become an integral part of the disease treatment algorithm.     

Risk of valvular heart disease associated with the use of dopamine agonists in Parkinson’s disease: a systematic review

A literature review was conducted to assess risk of cardiac valve regurgitation (CVR) associated with use of ergot-derived and non-ergot dopamine agonists (DAs) in patients with Parkinson’s disease (PD). Inclusion criteria: case-control/observational studies of >10 patients with PD treated with DAs, including a control group and assessment of incidence/risk of CVR. Of the 166 publications identified, 14 met all inclusion criteria and included 1,750 patients. In 11 of the studies, a significant increase in CVR frequency of any severity (at the aortic, mitral or tricuspid valve) in the ergot group vs. the non-ergot or control group was described. No study reported increased risk of CVR for non-ergot DAs, compared with controls. In the studies identified in the literature, the use of ergot-derived DAs (pergolide and cabergoline) in patients with PD was associated with increased risk of CVR. Increased risk of CVR was not associated with the use of non-ergot DAs.     

Treatment of Parkinson's disease should begin with a dopamine agonist.

The occurrence of side effects with long-term levodopa therapy, such as fluctuations in motor performance or abnormal movements, led to a search for new antiparkinsonian drugs. Dopamine agonists include ergot derivatives such as bromocriptine, lisuride, pergolide, and cabergoline and other agents which do not possess the ergot structure such as pramipexole and ropinirole. They all are powerful stimulators of the D2 dopamine receptor which probably underlies their therapeutic effects. The clinical consequences of their binding to other dopamine receptor subtypes (D1 or D3) remains unknown. They are usually prescribed in combination with levodopa when late side effects begin to occur. This review summarizes the available pharmacologic and clinical data to support the early use of dopamine agonists in Parkinson's disease. Several strategies can be used, such as monotherapy or "early" or "late" combination with levodopa. Results of recent well-performed, modern clinical trials show that early use of the new dopamine agonists is able to effectively control the clinical symptoms for more than 3 years thereby offering the possibility of delaying the occurrence of levodopa-induced late motor side effects.     

Valvular heart disease in Parkinson's disease vs. controls: An echocardiographic study.

Restrictive valvulopathy has been reported in association with dopamine agonist therapy in parkinsonian patients. The majority of reports have been related to pergolide, but anecdotal cases following treatment with bromocriptine or cabergoline have also been presented. It is presently unclear whether the potential induction of restrictive cardiac valvulopathy is a class effect of all dopamine agonists or if there is a differential risk between ergot and nonergot compounds. In this study, the frequency of a valvular regurgitation as assessed by routine transthoracic echocardiography was compared between 75 patients with Parkinson's disease (PD) treated with pergolide (n = 29), cabergoline (n = 13), pramipexole or ropinirole (n = 33), and 49 age-matched nonparkinsonian controls. The exposure to pergolide and cabergoline was associated with higher frequencies of valvular regurgitation grades 2 and 3 (31% and 47%) compared with age-matched controls (13%), while there was no increase of valvular regurgitation grades 2 and 3 in patients treated with nonergot compounds (10%). Evidence for restrictive valvulopathy was found in one patient treated with pergolide and cabergoline each. While this study shows similarly increased frequencies of valvular regurgitation in patients treated with the ergot agonists pergolide and cabergoline in comparison to both normal controls and patients treated with nonergot agonists, evidence for restrictive valvulopathy was only found in two cases. These results highlight the need for further prospective studies of the prevalence and underlying mechanisms of cardiac valvulopathy in PD patients treated with different dopamine agonists.     

Pramipexole in the treatment of Parkinson's disease: new developments

The nonergot dopamine agonist pramipexole is an efficient and safe drug for the treatment of Parkinson's disease. Clinicians may favor pramipexole over other dopamine agonists because of its suggested higher tolerability with respect to peripheral dopaminergic side effects. Importantly, nonergot dopamine agonists such as pramipexole may not cause restrictive valvular heart disease and may therefore represent the first choice in patients with valvular lesions under treatment with ergot dopamine agonists. However, particular caution has to be exercised in younger Parkinson's disease patients with a shorter disease duration regarding the occurrence of sudden onset of sleep. In light of cost-effectiveness and quality-of-life issues, its final significance for the initial treatment of patients with early Parkinson's disease remains to be determined.     

Ergoline and non-ergoline derivatives in the treatment of Parkinson's disease

There are a large variety of dopamine agonists available. Especially de novo patients are treated with dopamine agonists to avoid dyskinesia. Dopamine agonists can be subdivided into ergoline and non-ergoline derivatives. This distinction raises the question whether there are differences in the effects to treat symptoms, not only in the side effects between the individual dopamine agonists but also between these two groups. Pergolide is now considered a second line drug because of its particularly high tendency towards valvular heart disease. Some authors claim that all ergoline-derivatives may cause this problem, while own results do not necessarily support this view. We recommend performing echocardiography on those patients being treated with an ergot-derivative. New data support the view that all dopaminergic drugs may cause somnolence and that there is no preference for non-ergots. It may be that the number of gamblers is slightly higher among patients treated with pramipexole than in others. Dopamine agonists with a high affinity to D3 receptors have a good anti-anhedonic potency. In cell culture all dopamine agonists studied so far show neuroprotective properties in cell culture. The introduction of a slow-release formulation for ropinirole and the rotigotine and lisuride patches have opened new ways of continuous dopamine receptor stimulation. Taken together, dopamine agonists show individual properties and there are differences between ergot and non-ergot derivatives.     

Disinhibitory abnormal behavior induced by treatment of Parkinson disease

The treatment of Parkinson disease has considerably progressed in the last 20 years. However, such treatments results in the adverse event of disinhibitory abnormal behavior, which includes impulse control disorders, punding, and dopamine dysregulation syndrome. Pathological gambling is the most extensively studied among such abnormal behaviors. It has been associated with the use of dopamine agonists and its prevalence increases according to the does of the drugs. The maximum dose of the ergot dopamine agonist pergolide is 1.25 mg/day in Japan, which is a quarter of that used in Western countries. The maximum dose of the non-ergot dopamine agonist, pramipexole is 4.5 mg/day in Japan, which is the same as in Western countries. Pramipexole was launched in 2004 in Japan, and since then cases of pathological gambling associated with dopamine agonists used has been increasing. Because of the excellent health-care system in Japan, patients can easily acquire expensive dopamine agonists. Although the prevalence of these abnormal behaviors has not been studied in Japan, it could be highly proportionate to the amount of dopamine agonists. Disinhibitory abnormal behavior is also induced by deep brain stimulation of the subthalamic nucleus. This technology was approved in 2000 in Japan. The mechanisms by which these behaviors are induced are different between dopamine replacement therapy and deep brain stimulation. Parkinson disease patients and their caregivers occasionally believe the disinhibitory abnormal behavior as arising from the original personality of the patient rather than as an adverse event of treatment. Neurologists should be aware of the occurrence of disinhibitory abnormal behavior in the clinical practice.     

How to succeed in using dopamine agonists in Parkinson's disease

Dopamine receptor agonists are assuming increased importance in the treatment of both early and advanced symptoms of Parkinson's disease (PD). However, tolerability of these drugs can be a problem. Identifying patients who are at increased risk of adverse effects is central to using dopamine agonists in PD. The newer agonists, pramipexole and ropinirole, are generally adequate without levodopa for early symptoms and carry the hope for a more acceptable profile of long-term side-effects. In the patient with advanced disease, all four dopamine agonists significantly augment the response to levodopa, which reduces the problems of motor fluctuations and drug related dyskinesia. Understanding the common pitfalls when prescribing these drugs will facilitate their safety and efficacy.