Combination therapy with lisuride and L-dopa in the early stages of Parkinson's disease decreases and delays the development of motor fluctuations. Long-term study over 10 years in comparison with L-dopa monotherapy

A randomized, prospective study was carried out in order to investigate the efficacy of a dopamine agonist, lisuride, alone or in combination with levodopa, to minimize or postpone the development of motor fluctuations, compared with levodopa alone during 10 years' treatment of 90 patients with early Parkinson's disease. Only a small, and with time gradually decreasing number of patients obtained enough therapeutic benefit during long-term treatment with lisuride alone. Consequently, levodopa had to be added to the patients' regimen. During combined treatment with lisuride and levodopa the daily dose of levodopa needed for optimal therapeutic response was significantly lower than when using levodopa alone. The addition of levodopa to the lisuride regimen either from the beginning or at any time during long-term treatment according to clinical need, resulted in a therapeutic response in parkinsonian disability equal to that achieved with levodopa alone, but significantly decreased and postponed the development of motor fluctuations, end-of-dose failure and dyskinesias. Severe dopaminergic adverse events leading to withdrawal of the treatment were more frequent during treatment with lisuride and levodopa than with levodopa alone, but the lower mortality rate did not reach the level of statistical significance. In conclusion, according to the results obtained, it seems reasonable to consider a treatment strategy in early Parkinson's disease using a dopamine agonist, like lisuride, as the primary treatment and to delay the addition of levodopa until parkinsonian disability cannot be adequately controlled by a dopamine agonist.     

New strategies in the treatment of early Parkinson's disease

Over recent years I have been studying whether dopamine agonist treatment alone, or in early combination with levodopa, might institute a better long-term treatment in Parkinson's disease than levodopa alone. Indeed, early combination of levodopa with bromocriptine, pergolide or lisuride has indicated that this kind of treatment results in better management of Parkinson's disease with fewer fluctuations in disability, especially end-of-dose disturbances and dyskinesias, than treatment with levodopa alone. Furthermore, similar results were obtained by using lisuride in combination with selegiline and levodopa. However, during long-term treatment the changes in parkinsonian disability were equal in all treatment groups with or without selegiline. Thus, the possible efficacy of selegiline in slowing down the progression of Parkinson's disease requires further investigations. As a new treatment strategy it appears advisable to initiate the dopaminergic treatment in early Parkinson's disease by using initially selegiline and a dopamine agonist and by adding levodopa when the therapeutic response is insuifficient. Another alternative would be to start with selegiline alone, then add a dopamine agonist and, finally, levodopa.     

Therapeutic strategies to prevent motor complications in Parkinson's disease

Dopaminergic treatment of Parkinson's disease (PD) leads to significant improvement in Parkinsonian features; however, the treatment response is hampered by the appearance of motor complications, including dyskinesias and motor fluctuations. These motor complications have a significant negative impact on quality-of-life. Therapeutic strategies using different types and timing of dopaminergic therapy may influence the emergence of motor complications. While sustained release preparations of levodopa have not shown benefit over immediate release preparations, the early combination of a dopamine agonist with levodopa appears to reduce the onset of motor fluctuations. An even larger body of evidence has found that initiating treatment with a dopamine receptor agonist (as compared to immediate release levodopa) is associated with a reduction in motor fluctuations, particularly dyskinesias. These data have led to evidence-based medicine evaluations indicating that the use of dopamine agonists is efficacious and clinically useful for the prevention of motor complications.     

Levodopa/DDCI and entacapone is the preferred treatment for Parkinson's disease patients with motor fluctuations in routine practice: a retrospective, observational analysis of a large French cohort

Levodopa is the gold standard drug for the symptomatic control of Parkinson's disease (PD). However, long-term treatment with conventional formulations [levodopa and a dopa decarboxylase inhibitor (DDCI)], is associated with re-emergence of symptoms because of wearing-off and dyskinesia. Treatment with levodopa/DDCI and entacapone extends the half-life of levodopa, avoiding deep troughs in levodopa plasma levels and providing more continuous delivery of levodopa to the brain. In this open-label, retrospective, observational study we investigated the effects of levodopa/DDCI and entacapone therapy in 800 PD patients with motor fluctuations. Levodopa/DDCI and entacapone treatment was assessed as good/very good in improving motor fluctuations (64%) and activities of daily living (ADL; 62%). The therapeutic utility was considered to be good/very good in 70% of cases. Moreover, there was a reduction in levodopa dose in 20% of patients. Neurologists preferred levodopa/DDCI and entacapone compared with increasing levodopa dosage, dose-fractionation or addition of a dopamine agonist (63%, 29% and 23% of patients respectively). Reasons included achieving more continuous dopaminergic stimulation (40%), reducing motor fluctuations (54%) and improving ADL (41%). This analysis reveals the preference of neurologists for levodopa/DDCI and entacapone over conventional levodopa-modification strategies for the effective treatment of PD motor fluctuations in clinical practice.     

Combined bromocriptine-levodopa therapy early in Parkinson's disease

Compared with levodopa, treatment of parkinsonism for 3 years with bromocriptine alone resulted in less fluctuation and peak-dose dyskinesia, but also less improvement in parkinsonian disability. Only a few of the 76 patients had long-term benefit on chronic bromocriptine therapy. However, combined bromocriptine and levodopa therapy had a therapeutic response equal to that of levodopa alone, with fewer fluctuations and peak-dose dyskinesias. Treatment should begin with a low dose of levodopa and a dopamine agonist.     

Subcutaneous continuous apomorphine infusion in fluctuating patients with Parkinson's disease: long-term results

Fluctuations in motor disability and dyskinesias are the major problem in the long-term treatment of Parkinson's disease (PD). Many authors and ourselves have shown that by giving patients a continuous infusion of levodopa it is possible to control motor fluctuations. Levodopa can be administered continuously only be intravenous, intragastric or intrajejunal delivery. Continuous dopaminergic stimulation an be achieved more easily by infusing dopamine agonists subcutaneously. Apomorphine is a potent water-soluble dopamine receptor agonist that has been shown to successfully control motor fluctuation when subcutaneously infused in complicated parkinsonian patients. We report the clinical data of 30 PD patients having at least five years of treatment with subcutaneous continuous apomorphine infusion.     

Pharmacokinetic and pharmacodynamic considerations in management of motor response fluctuations in Parkinson's disease

Recent advances in the understanding of the pharmacokinetics of levodopa and other anti-Parkinson agents have brought about the development of rational approaches to the management of levodopa-related fluctuations in motor performance that plague the majority of patients with advanced PD. The rapid systemic clearance of levodopa underlies the "short duration" response to the drug, which is progressively unmasked as PD progresses and central dopamine synthetic and storage capacity can no longer buffer fluctuations in plasma levodopa levels. Dyskinesias may be considered a secondary pharmacodynamic consequence of such pharmacokinetically induced oscillations in brain dopamine levels. Therapeutic approaches aimed at stabilizing brain dopaminergic activity include the use of slowly releasing galenic formulations of levodopa, synthetic dopamine agonists of long-lasting biologic activity, and drugs such as deprenyl that act as "dopamine extenders." It remains to be seen whether early use of such treatment approaches will reduce the prevalence of motor response fluctuations, which are one of the most disabling complications of long-term treatment of PD.     

Evidence-based initiation of dopaminergic therapy in Parkinson's disease

The mainstay of Parkinson's disease (PD) therapy is levodopa. The crucial question is when should levodopa be initiated? Levodopa provides the most potent motor benefit for PD, but longer term use is marked by the development of motor complications such as fluctuations in response and involuntary motor movements. Dopamine agonists reduce the risk of development of motor complications in the 5-year term. However, side effects may change the risk-benefit of dopamine agonist first strategies. In the following, the evidence for levodopa and dopamine agonists as initial monotherapy for PD is examined.

     

Parkinson’s disease: Is the initial treatment established?

Recent studies have suggested that initial dopamine agonist therapy with pramipexole or ropinirole may slow the progression of Parkinson’s disease (PD) and also reduce the subsequent risk of levodopa motor complications. This presumed effect on PD progression, however, could be artifactual, resulting from the influence of chronic drug treatment on regulation of dopamine system proteins. With respect to levodopa motor complications, there is no dispute that pramipexole and ropinirole are effective in reducing levodopa dyskinesias and motor fluctuations; however, it is not clear that they must be started early, as opposed to initiation only after the levodopa complications develop. Levodopa therapy has numerous advantages that include greater efficacy, much lesser expense, simpler administration, and a lower frequency of hallucinosis and somnolence. Carbidopa/levodopa, pramipexole, and ropinirole are all appropriate first choices in the treatment of PD.     

Pulsatile or continuous dopaminomimetic strategies in Parkinson's disease

Levodopa is the most effective treatment for Parkinson's disease (PD) for both motor and non-motor control. Pulsatile levodopa administration likely contributes to the development of motor fluctuations and dyskinesia after a few years. All studies comparing levodopa versus dopamine agonist early therapy indicate that initiation with agonists is associated with a reduced risk of motor complications - in particular, dyskinesias - possibly because agonists' longer half-lives provide continuous dopaminergic delivery. Indeed, this therapeutic strategy may delay the emergence of motor fluctuations and dyskinesia which is essential to maintaining satisfactory quality of life. In advanced disease various levodopa-based strategies may be tried to control motor complications, such as dose fragmentation (smaller, more frequent dosing) or the use of orally administered, liquid levodopa formulations that may reduce off-time intervals or facilitate absorption. More recently introduced, continuous levodopa delivery by duodenal infusion (but also apomorphine infusion) may represent a more effective approach to treat motor complications in advanced PD, and its effect can be perceived by improvement both in clinical scales as well as in health-related items. Infusion therapies may reverse motor complications in complicated patients with significant benefit on quality of life.     

Initial treatment of early Parkinson’s disease: A review of recent, randomized controlled trials

Many studies have shown dopamine agonists to significantly improve parkinsonian symptoms compared with placebo in early Parkinson’s disease (PD), but how do agonists compare with the standard treatment of levodopa? Recently, three large, multicenter, randomized controlled studies directly comparing a dopamine agonist with levodopa as initial therapy in early PD have been published. These studies suggest that although both agents effectively ameliorate parkinsonian symptoms, levodopa was superior to dopamine agonists as measured by improvement in Unified Parkinson’s Disease Rating Scale (UPDRS) scores. However, levodopa was more frequently associated with dopaminergic motor complications, and the dopamine agonists were more commonly associated with adverse events. Until further studies clearly demonstrate the beneficial effects of one therapeutic strategy over another, the decision to initiate treatment in early PD with either an agonist or levodopa will be based on the favorable motor complication profile of agonists versus the more potent antiparkinsonian effects and the favorable side-effect profile of levodopa.     

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.     

Continuous dopaminergic delivery in Parkinson’s disease

Motor fluctuations and dyskinesias occur in the majority of patients with Parkinson’s disease (PD) and are likely to result from changes in dopamine production, storage and release, occurring as consequences of the nigrostriatal degenerative process. All studies comparing levodopa versus dopamine agonist early therapy indicate that initiation with agonists is associated with a reduced risk of motor complications —in particular, dyskinesias— possibly because agonists’ longer half-lives provide continuous dopaminergic delivery. In advanced PD patients, switching from a pulsatile to continuous dopaminergic delivery may widen patients’ therapeutic window. Currently, this can be accomplished only with subcutaneous apomorphine or duodenal levodopa infusions. Apomorphine is a highly soluble agonist whose effect is similar to dopamine. Conversely, replacing whole oral therapy with levodopa infusion bypasses gastric emptying and avoids peaks and troughs in plasma by releasing levodopa in the duodenum/jejunum.

     

Treatment of Parkinson's disease: levodopa as the first choice

The introduction of levodopa in the 1960s revolutionised the treatment of Parkinson's disease (PD), and it continues to be the most effective symptomatic therapy. The vast majority of PD patients who start treatment with L-dopa experience good to excellent functional benefit. In vitro studies with high doses of L-dopa and absent glia had shown that it may be neurotoxic, but other tissue culture studies show L-dopa to be neuroprotective. Most studies in animal models and clinico-pathological and mortality studies in humans failed to show evidence in favour of accelerated dopaminergic neuronal loss with long-term L-dopa therapy.L-dopa continues to be beneficial throughout the course of PD, although as the disease progresses, escape of some symptoms from adequate control may occur and refractory disabilities such as impaired balance, dysarthria, cognitive decline and hallucinations may emerge. Treatment of advanced PD may also be complicated by the emergence of motor fluctuations and dyskinesias. Studies in animal models and in humans show that these motor complications are not specific to a particular dopaminergic agent, but that they are related both to the extent of the striatal lesion and to the mode of application of dopaminergic agents: Pulsatile administration of L-dopa and of the dopamine agonist apomorphine causes more motor complications than continuous striatal dopaminergic receptor stimulation, and continuous administration can alleviate existing dyskinesias and fluctuations. Several controlled studies comparing levodopa and dopamine agonists as initial treatment have attempted to answer the question whether delaying L-dopa therapy can reduce the occurrence of motor complications. Three medium-term (3-5 years) and one 10-year study showed less dyskinesia in the first five years of treatment in patients who had started therapy with a dopamine agonist. However, these studies also consistently showed that levodopa provided better functional improvement in the first years of treatment. Ten-year follow-up data in patients randomised to L-dopa or bromocriptine also showed a slightly lower incidence of motor complications in the bromocriptine arm. However, this difference was not significant for the clinically relevant moderate and severe forms of dyskinesias and fluctuations, and was achieved at the expense of significantly worse disability scores during the first years of therapy. Furthermore, the relative impact of motor disability and dyskinesias on patients' quality of life remains to be established. Concordance is essential in the optimum treatment of PD and patients should be informed of the various therapeutic options available. Treatment should respect individual patients' needs and take into account their particular functional disabilities and specific handicaps. Low-dose L-dopa therapy (up to 400 mg/day), however, remains the most effective initial treatment of choice for the majority of patients.     

Problems associated with long-term levodopa treatment of Parkinson's disease

ABSTRACT — Levodopa treatment improves significantly not only the parkinsonian disability but also the mortality rate. However, during long-term levodopa treatment the therapeutic benefit gradually declines. Furthermore, most cognitive skills improve initially, but long-term levodopa treatment is associated with declining intellectual capacity and dementia.
In patients on long-term levodopa treatment there seems to be a low threshold for certain clinical side-effects, especially postural hypotension, psychiatric disturbances and various types of fluctuations in disability. Low age at onset of Parkinson's disease, and at the commencement of levodopa therapy, the duration of levodopa treatment and a high dose of levodopa seem to be significant risk factors for the development of response fluctuations, but not the pretreatment duration of Parkinson's disease nor the disability of the patients.
A readjustment of the levodopa dosage, and as an adjuvant drug treatment, deprenyl, a specific inhibitor of MAO type B, or a direct-acting dopamine agonist may prove helpful in the management of fluctuations in disability. It is important, moreover, to try to prevent these phenomena by taking into account the predictive risk factors of response fluctuations in the treatment strategy of Parkinson's disease.     

Quetiapine attenuates levodopa-induced motor complications in rodent and primate parkinsonian models

The contribution of serotoninergic mechanisms to motor dysfunction in Parkinson's disease (PD) has yet to be fully elucidated. Recent clinical observations increasingly suggest that drugs able to block serotonin 5HT2A/C receptors can benefit patients with certain extrapyramidal movement disorders. To further explore the roles of these and other neurotransmitter receptors in the pathogenesis of parkinsonian signs and levodopa-induced dyskinesias; we evaluated the effects of quetiapine, an atypical antipsychotic with 5HT2A/C and D2/3 antagonistic activity, on motor behavior in 6-hydroxydopamine-lesioned rats and MPTP-lesioned nonhuman primates. In hemiparkinsonian rats, quetiapine (5 mg/kg, po) reversed the shortened motor response to levodopa challenge produced by 3 weeks of twice-daily levodopa treatment (P < 0.01). Quetiapine (5 mg/kg po) also normalized the shortened response to the acute injection of either a dopamine D1 receptor agonist (SKF 38392) or a D2 agonist (quinpirole) in rats that had received chronic levodopa treatment. Quetiapine had no effect on parkinsonian dysfunction when given alone or with levodopa to parkinsonian rats and monkeys. Quetiapine (4 mg/kg, po) did, however, substantially reduce levodopa-induced dyskinesias when coadministered with levodopa (P < 0.05). These results suggest that quetiapine could confer therapeutic benefits to patients with levodopa-induced motor complications. Moreover, our findings may indicate that 5HT2A/C receptor-mediated mechanisms, alone or in combination with other mechanisms, contribute to the pathogenesis of the altered motor responses associated with the treatment of PD.     

Levodopa or dopamine agonists, or deprenyl as initial treatment for Parkinson's disease. A randomized multicenter study

Objectives: levodopa improves the quality of life in parkinsonian patients, however long term response is compromised by the emergence of motor fluctuations and dyskinesias. The aim of this study was to compare the occurrence of motor fluctuations and dyskinesias in previously untreated patients assigned to receive levodopa, a dopamine agonist or deprenyl.Thirty-five neurological departments in Italian hospitals participated in this randomized open trial. Patients with Parkinson's disease, who required the initiation of an effective antiparkinsonian treatment, were randomly assigned to receive levodopa, dopamine agonists or deprenyl. The end-points were motor dyskinesias and motor fluctuations occurring in a median follow-up period of about 3years.After a median follow-up of 34months, motor fluctuations and dyskinesias were less frequent in patients assigned to a dopamine agonist or deprenyl than in patients assigned to levodopa (relative risk [RR] 0.5, 95% confidence interval [95% CI] 0.3-0.8, and RR=0.6, 95% CI 0.3-0.9, respectively), but dopamine agonists were less effective and less well tolerated than levodopa. The lower frequency of motor fluctuations in patients assigned to deprenyl was no longer statistically significant when prognostic predictors were considered in a multivariable analysis. Long-term mortality did not differ in the three arms of the study. Dopamine agonists and deprenyl can be considered as an alternative to levodopa for starting treatment in Parkinson's disease patients. However, on clinical grounds, only small advantages are expected over the traditional therapy initiation with levodopa.     

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.     

Early combination of bromocriptine and levodopa in the treatment of Parkinson's disease: a 5-year follow-up

Compared with levodopa, long-term bromocriptine treatment of parkinsonian patients for 5 years resulted in fewer fluctuations of disability and peak-dose dyskinesias, but also less improvement in parkinsonian disability. Combination of low-dose bromocriptine and levodopa resulted in a therapeutic response equal to that of levodopa alone but with fewer end-of-dose disturbances and peak-dose dyskinesias. I believe that treatment should begin promptly with a low dose of levodopa, combined with a dopamine agonist such as bromocriptine.     

New strategies in motor parkinsonism

A satisfactory motor control can be achieved for many years in Parkinson's disease (PD). Clinical management is more complex when disease progresses and occurrence of motor fluctuations and dyskinesias negatively impacts on patients' quality of life. Mobility depends increasingly on levodopa peripheral bioavailability. Medical strategies consist of raising the number of levodopa administrations and the association with COMT inhibitors, entacapone or the more potent tolcapone. MAO-B inhibitors rasagiline or selegiline can be also added. When these options fail, achievement of motor control requires more complex therapeutic strategies: continuous infusion of dopaminergic drugs or neuromodulation with deep brain stimulation (DBS). Apomorphine is a dopamine agonist that can provide motor benefit similar to dopamine, but its use is limited by compliance, local skin reactions at the site of injection and risk of psychiatric adverse events, particularly when round-the-clock administration is used. DBS of the subthalamic nucleus is very effective but feasible only for a small number of patients mostly because of age constraints. Continuous duodenal infusion of levodopa/carbidopa allows replacement of oral therapy resulting in marked improvement of quality of life and activities of daily living. Interestingly, this procedure produces a satisfactory therapeutic response that is paralleled by a reduction in dyskinesia severity.