Rotigotine transdermal delivery for the treatment of Parkinson's disease

Mathematical modelling of microneedle-mediated transdermal delivery of drug nanocarriers into skin tissue and circulatory system

Microneedle-mediated transdermal delivery using nanocarriers can successfully overcome the barrier of the stratum corneum and protect drugs from elimination in skin tissues. However, the effectiveness of drug delivery to different layers of skin tissues and the circulatory system varies considerably, subject to the properties of the drug delivery system and delivery regime. How to maximise delivery outcomes remains unclear. In this study, mathematical modelling is employed to investigate this transdermal delivery under various conditions, using the skin model that is reconstructed based on the realistic skin anatomical structure. Treatment efficacy is evaluated in terms of drug exposure over time. The modelling results demonstrate the complex dependence of drug accumulation and distribution on the nanocarrier properties, microneedle properties and environment in different skin layers and blood. Specifically, delivery outcomes in the entire skin and blood can be improved by increasing the loading dose and reducing microneedle spacing. However, several parameters need to be optimised with respect to the specific location of the target site in the tissue for better treatment; these include the drug release rate, nanocarrier diffusivity in microneedle and skin tissue, nanocarrier transvascular permeability, nanocarrier partition coefficient between tissue and microneedle, microneedle length, wind speed and relative humidity. The delivery is less sensitive to the diffusivity and physical degradation rate of free drugs in microneedle, and their partition coefficient between tissue and microneedle. Results obtained from this study can be used to improve the design of the microneedle-nanocarrier combined drug delivery system and delivery regime.

Polymorphism of Pradofloxacin: Crystal Structure Analysis, Stability Study, and Phase Transformation Behavior

PURPOSE

Pradofloxacin is an important antibiotic with poor physical stability. At present, there is no systematic study on its polymorphic form. The purpose of this study is to develop new crystal forms to improve the stability of Pradofloxacin and systematically study the crystal transformation relationships to guide industrial production.

METHOD

In this work, three solvent-free forms (Form A, Form B and Form C), a new dimethyl sulfoxide solvate (Form PL-DMSO) and a new hydrate (Form PL-H) were successfully obtained and the single crystal data of Form A, Form B and Form PL-DMSO were solved for the first time. Various solid state analysis techniques and slurry experiments have been used to evaluate the stability and determine phase transformation relationships of five crystal forms, the analysis of crystal structure provided theoretical support for the results.

RESULT

The water vapor adsorption and desorption experiences of Forms A, B, C and Form PL-H were studied, and the results show that the new hydrate has good hygroscopic stability and certain development potential. The thermal stability of different forms was determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and the crystal structure shows that there are more hydrogen bonds and C - H···π interactions in form B, which is the reason why Form B is more stable than form A. Finally, the phase transformation relationships of the five crystal forms were systematically studied and discussed.

CONCLUSION

These results are helpful to provide guiding methods in the production and storage of pradofloxacin.

Management of Motor Symptoms for Patients with Advanced Parkinson's Disease without Safe Oral Access: A Scoping Review

Context: Parkinson's disease (PD) is the second most common neurodegenerative disorder worldwide. Oral medications for control of motor symptoms are the mainstay of treatment. However, as the disease progresses, patients with PD may develop dysphagia that prohibits them from safely taking oral medications. Currently there are no clinical guidelines for managing distressing motor symptoms in patients with PD and severe dysphagia, which can therefore be quite challenging. Objectives: To provide an exhaustive summary of current literature on pharmacological interventions for patients with PD who do not have safe oral access in managing distressing motor symptoms. Indication, route, doses, frequency, outcome, and adverse effects will be discussed. Methods: A scoping review using Medline, Embase, CENTRAL, CINAHL, AgeLine, and PsycINFO databases (1946-2021) was conducted. Articles examining patients with PD and dysphagia who are eligible to receive palliative care or at end of life were included. Studies that included patients who were also on oral PD medications or received device-aided therapy were excluded from this review. Results: A total of 3821 articles were screened for title and abstract, 259 were selected for full-text review, and 20 articles were selected for data extraction. These included five case reports, one retrospective cohort study, one book chapter, and 13 narrative reviews. There are very few articles addressing the issue of treatment of patients with advanced PD who are unable to take oral medications. Although rotigotine patch and apormorphine injections are most frequently recommended, there are no clinical trials in this patient population to support those recommendations. Conclusion: This study highlights a need for further research examining the efficacy and dosing of nonoral medications in advanced PD with dysphagia.

Biomaterials in the treatment of Parkinson's disease

Parkinson's disease is a neurodegenerative disease, the treatment of which is mainly centred around supplementation of dopamine. Additional targets have been identified and newer chemotherapeutic agents have been introduced but their clinical efficacy is limited due to solubility, bioavailability issues and inability to cross the blood-brain barrier (BBB). A wide range of biomaterials ranging from biomolecules, polymers, inorganic metal and metal oxide nanoparticles have been employed to assist the delivery of these therapeutic agents into the brain. Additionally, strategies to deliver cells to restore the dopaminergic neurons also have shown promise due to the integration of biocompatible materials that aid neurogenesis through a combination of topographical, chemical and mechanical cues. Neuroprosthetics is an area that may become significant in treatment of motor deficits associated with Parkinson's disease, and involves development of highly conductive and robust electrode materials with excellent cytocompatibility. This review summarizes the major role played by biomaterials in design of novel strategies and in the improvement of existing therapeutic methods as well as the emerging trends in this domain.

'Dopamine agonist Phobia' in Parkinson's disease: when does it matter? Implications for non-motor symptoms and personalized medicine

INTRODUCTION

Dopamine agonists have been widely used to treat patients with Parkinson's disease, but concerns related to their well-known side effects might prevent their use even when indicated. In this review, the authors describe for the first time the concept of 'Dopamine Agonist Phobia', a pharmacophobia that the authors believe might affect clinicians, and they provide evidence of the benefits of dopamine agonists, focusing on non-motor symptoms.

AREAS COVERED

The authors performed an extensive literature research, including studies exploring the use of dopamine agonists for the treatment of non-motor symptoms. The authors indicate the highest level of evidence in each section.

EXPERT OPINION

'Dopamine Agonist Phobia' may preclude valid therapeutic options in selected cases, specifically for the treatment of non-motor symptoms. Thus, the authors propose a personalized approach in Parkinson's disease treatment, and encourage a thoughtful use of dopamine agonists, rather than an overall nihilism.

Molecular basis of dopamine replacement therapy and its side effects in Parkinson's disease

There is currently no cure for Parkinson's disease. The symptomatic therapeutic strategy essentially relies on dopamine replacement whose efficacy was demonstrated more than 50 years ago following the introduction of the dopamine precursor, levodopa. The spectacular antiparkinsonian effect of levodopa is, however, balanced by major limitations including the occurrence of motor complications related to its particular pharmacokinetic and pharmacodynamic properties. Other therapeutic strategies have thus been developed to overcome these problems such as the use of dopamine receptor agonists, dopamine metabolism inhibitors and non-dopaminergic drugs. Here we review the pharmacology and molecular mechanisms of dopamine replacement therapy in Parkinson's disease, both at the presynaptic and postsynaptic levels. The perspectives in terms of novel drug development and prediction of drug response for a more personalised medicine will be discussed.

A review of adverse events linked to dopamine agonists in the treatment of Parkinson's disease

INTRODUCTION

Dopamine agonists are highly effective as adjunctive therapy to levodopa in advanced Parkinson's disease. These drugs have rapidly gained popularity as a monotherapy in the early stages of Parkinson's disease for patients less than 65-70 years old since they are about as effective as levodopa but patients demonstrate a lower tendency to develop motor complications. However, dopamine agonists could have peripheral and central side-effects which are often the reason for the discontinuation of the treatment.

AREAS COVERED

This article presents an overview of the efficacy and the potential negative effects related to the use of dopamine agonists in the treatment of Parkinson's disease.

EXPERT OPINION

Beyond the new generation non ergot dopamine agonists, no strong evidences allow the choice of a specific dopamine agonists for Parkinson 's disease treatment and by now dopamine agonists treatment should be tailored on specific adverse events profile.

Critical appraisal of rotigotine transdermal system in management of Parkinson's disease and restless legs syndrome - patient considerations

Rotigotine (RTG) is a dopamine agonist that is used as mono and adjunct therapy to treat Parkinson’s disease, and as therapy for moderate-to-severe restless legs syndrome. RTG is the only dopamine agonist currently available as a 24-hour/day transdermal system, providing once-a-day dosing. As a transdermal patch, RTG bypasses the gastrointestinal tract, making it a treatment option for patients with dysphagia. The use of RTG also avoids the need to schedule administration of medication around meals. This review provides a critical appraisal of RTG as treatment of Parkinson’s disease and RLS.

Impulse control disorder in patients with Parkinson's disease under dopamine agonist therapy: a multicentre study

BACKGROUND

Impulse control disorders (ICDs) encompass a wide spectrum of abnormal behaviour frequently found in cases of Parkinson's disease (PD) treated with dopamine agonists (DAs). The main aim of this study was to analyse ICD prevalence with different DAs.

METHODS

We carried out a multicentre transversal study to evaluate the presence of ICDs in patients with PD chronically treated (>6 months) with a single non-ergolinic DA (pramipexole, ropinirole, or rotigotine). Clinical assessment of ICD was performed using the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's disease.

RESULTS

Thirty-nine per cent of patients (91/233) fulfilled the clinical criteria for ICD. The group of patients with ICD symptoms (ICD+) differed from those without ICD symptoms (ICD-) in younger age and type of DA intake. Oral DA treatment (pramipexole and ropinirole) was associated with higher risk of ICDs compared with transdermal DA (rotigotine): 84/197 (42%) patients treated with oral DA developed ICD, versus 7/36 (19%) patients treated with transdermal DA (Fisher's exact text <0.01). In univariate analysis, a younger age (p<0.01), treatment with rasagiline (p<0.05), and especially treatment with an oral DA (pramipexole or ropinirole) (p<0.01) were significantly associated with ICD. Multivariate analysis confirmed that oral DA remained significantly associated with ICD (p: 0.014, OR: 3.14; 1.26-7.83).

CONCLUSIONS

ICD was significantly associated with the use of the non-ergolinic oral DA (pramipexole and ropinirole) when compared with transdermal non-ergolinic DA (rotigotine). Since pramipexole, ropinirole and rotigotine are non-ergolinic DAs with very similar pharmacodynamic profiles, it is likely that other factors including route of administration (transdermal vs oral) explain the difference in risk of ICD development.

No influence of the CYP2C19-selective inhibitor omeprazole on the pharmacokinetics of the dopamine receptor agonist rotigotine

Rotigotine, a non-ergolinic dopamine receptor agonist administered transdermally via a patch, is metabolized by several cytochrome P-450 (CYP450) isoenzymes, including CYP2C19. This open-label, multiple-dose study evaluated the effect of omeprazole, a competitive inhibitor of CYP2C19, on the pharmacokinetics of rotigotine and its metabolites under steady-state conditions in healthy male subjects (of the extensive metabolizer phenotype, CYP2C19). Subjects received rotigotine 2 mg/24 hours on days 1-3, 4 mg/24 hours on days 4-12, and omeprazole 40 mg once daily on days 7-12 immediately after patch application. Blood and urine samples were collected on days 6 and 12 to evaluate rotigotine pharmacokinetic parameters alone and in the presence of omeprazole. Data from 37 subjects were available for pharmacokinetic analysis. Point estimates (90% confidence intervals, CI) for the ratios of AUC(0-24)SS and Cmax,SS of unconjugated rotigotine for the comparison rotigotine + omeprazole:rotigotine alone were close to 1 (0.9853 [0.9024, 1.0757] for AUC(0-24)SS and 1.0613 [0.9723, 1.1585] for Cmax,SS ) with 90% CIs within the acceptance range for bioequivalence (0.80, 1.25). Selective inhibition of CYP2C19 by omeprazole did not alter the steady-state pharmacokinetic profile of rotigotine or its metabolites. Thus, rotigotine dose adjustment is not required in patients receiving omeprazole, or other CYP2C19 inhibitors.

Effects of rotigotine on Parkinson's disease-related sleep disturbances

INTRODUCTION

Sleep abnormalities are a frequent non-motor symptom and a prominent cause of disability in patients with Parkinson's disease (PD).

AREAS COVERED

This review discusses what is currently known about the characteristics of sleep disturbances in PD patients and attempts to clarify the role of dopaminergic pathways in their pathogenesis as well as the beneficial effect of dopaminergic agents in their treatment. In particular, this review will focus on the effects of transdermal rotigotine on improving PD-related sleep disorders.

EXPERT OPINION

Sleep disturbances are common in PD, and these disturbances can be reduced or resolved, in large part, by preventing or attenuating nocturnal and early morning motor and non-motor symptoms of PD. The studies discussed within this review suggest that sleep disorders are not just a consequence of motor impairment and dopaminergic therapy but are an integral part of the neurodegenerative process of PD. This is supported by the appearance of specific sleep disturbances, which are related to degeneration of the brainstem areas involved in the regulation of sleep/wake states in advance of typical PD symptoms. Development of more detailed diagnostic tools aimed at detecting sleep disturbances and at defining the main causative factors of sleep disturbances in PD will lead to improved treatment of these disturbances.

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.

The development of the rotigotine transdermal patch: a historical perspective

The rotigotine transdermal system is a dopamine receptor agonist delivered over a 24-hour period. It is approved for the treatment of idiopathic Parkinson's disease (PD). This article reviews the development of the rotigotine transdermal system, including rotigotine's receptor profile, steady-state pharmacokinetics, and metabolism. Preclinical studies of rotigotine in animal models of PD and proof-of-concept studies in patients with PD are reviewed. These preclinical and clinical studies established this system as an effective method for providing continuous rotigotine delivery across the skin providing the basis for continued clinical development of rotigotine for the treatment of early and advanced PD.

Rotigotine transdermal system for long-term treatment of patients with advanced Parkinson's disease: results of two open-label extension studies, CLEOPATRA-PD and PREFER

Open-label extensions [studies SP516 (NCT00501969) and SP715 (NCT00594386)] of the CLEOPATRA-PD and PREFER studies were conducted to evaluate the safety, tolerability and efficacy of the dopaminergic agonist, rotigotine, over several years of follow-up in patients with advanced Parkinson’s disease (PD). Eligible subjects completing the double-blind trials received open-label adjunctive rotigotine (≤16 mg/24 h) for up to 4 and 6 years in Studies SP516 and SP715, respectively. Safety and tolerability were assessed using adverse events, vital signs and laboratory parameters, and efficacy assessed using the unified Parkinson’s disease rating scale (UPDRS). Of the 395 and 258 patients enrolled in the SP516 and SP715 studies, 48 and 45 % completed, respectively. Adverse events were typically dopaminergic effects [e.g., somnolence (18–25 %/patient-year), insomnia (5–7 %/patient-year), dyskinesias (4–8 %/patient-year) and hallucinations (4–8 %/patient-year)], or related to the transdermal application of a patch (application site reactions: 14–15 %/patient-year). There were no clinically relevant changes in vital signs or laboratory parameters in either study. Mean UPDRS part II (activities of daily living) and part III (motor function) total scores improved from double-blind baseline during dose titration, then gradually declined over the maintenance period. In study SP516, mean UPDRS part II and III total scores were 0.8 points above and 2.8 points below double-blind baseline, respectively, at end of treatment. In study SP715, mean UPDRS part II and III total scores were 4.1 points above and 0.2 points below baseline, respectively, at end of treatment. In these open-label studies, adjunctive rotigotine was efficacious with an acceptable safety and tolerability profile in patients with advanced PD for up to 6 years.

Long-term safety and tolerability of rotigotine transdermal system in patients with early-stage idiopathic Parkinson's disease: a prospective, open-label extension study

PURPOSE

This prospective, open-label extension (SP702; NCT00594165) of a 6-month double-blind, randomized study investigated the long-term safety and tolerability of rotigotine transdermal system in early Parkinson's disease (PD).

METHODS

Patients with early-stage idiopathic PD received transdermal rotigotine for up to 6 years at optimal dose (up to 16 mg/24h). Adjunctive levodopa was allowed. Primary outcomes included adverse events (AEs) and extent of rotigotine exposure. Other outcomes included time to levodopa, incidence of dyskinesias, and efficacy using the Unified Parkinson's Disease Rating Scale (UPDRS) II+III total score.

RESULTS

Of 217 patients entering the open-label study, 47% were still in the study upon closure; 24% withdrew because of AEs and 6% because of lack of efficacy. The median exposure to rotigotine was 1910 days (≈ 5 years, 3 months; range 1-2188 days). Most common AEs were somnolence (23% per patient-year), falls (17%), peripheral edema (14%), nausea (12%), and application site reactions (ASRs; 12%). 3% withdrew because of ASRs. 26% patients did not initiate levodopa; of those who did, fewer than half started levodopa in the first year. Dyskinesias were reported by 25% patients; the majority (83%) reported their first episode after initiating levodopa. Mean UPDRS II+III total scores remained below double-blind baseline for up to 2 years of open-label treatment.

CONCLUSION

This is the longest interventional study of rotigotine conducted to date. Transdermal rotigotine was generally well tolerated for up to 6 years; AEs reported were similar to those observed in shorter studies and led to discontinuation in only 24% patients.

Levodopa-carbidopa intestinal gel for treatment of advanced Parkinson's disease

BACKGROUND

Levodopa is the mainstay of Parkinson's disease (PD) treatment, but is often eventually associated with disabling motor complications in patients with advanced PD. The inability of perorally administered levodopa to provide more physiologic continuous dopaminergic stimulation (CDS) is a leading hypothesis to explain these complications.

OBJECTIVE

To investigate the cumulative efficacy and safety, and re-evaluate the role, of levodopa-carbidopa intestinal gel (LCIG) infusion in treatment of advanced PD patients experiencing levodopa-associated motor complications, through its purported mechanism for providing CDS.

METHODS

Literature searches in the MEDLINE/PubMed database were used to identify peer-reviewed publications examining the role of CDS in levodopa-associated motor complications and pharmacologic strategies for CDS, focusing on LCIG infusion for advanced PD patients.

RESULTS

LCIG, an aqueous gel, is continuously infused (daytime only or 24 h) via a portable pump and tube permanently inserted into the duodenum through percutaneous endoscopic gastrostomy (PEG). LCIG infusion provides stable levodopa plasma levels, which are significantly less variable than those with oral levodopa. Clinical trials indicate LCIG may significantly improve motor complications (reduction of time in 'off' and time in 'on with dyskinesias'), motor scores using the Unified Parkinson's Disease Rating Scale (UPDRS), non-motor symptomatology (Non-motor Symptom Scale) and health-related quality of life (HRQOL) in advanced PD patients. The adverse-event profile of LCIG is similar to that of oral levodopa, although technical problems with the infusion device have occurred in up to 70% of patients.

CONCLUSION

LCIG has demonstrated efficacy in reducing levodopa-associated motor complications in patients with advanced PD, and improving UPDRS and HRQOL scores. Because it involves PEG and its associated risks, LCIG is recommended for patients in whom motor fluctuations and dyskinesias are inadequately treated with traditional peroral medication. For these patients, LCIG can be a valuable alternative to deep brain stimulation (DBS), especially when DBS is contraindicated. These conclusions are limited by the modest number and size of completed randomized, controlled trials of LCIG.

Rotigotine effects on early morning motor function and sleep in Parkinson's disease: a double-blind, randomized, placebo-controlled study (RECOVER)

In a multinational, double-blind, placebo-controlled trial (NCT00474058), 287 subjects with Parkinson's disease (PD) and unsatisfactory early-morning motor symptom control were randomized 2:1 to receive rotigotine (2–16 mg/24 hr [n = 190]) or placebo (n = 97). Treatment was titrated to optimal dose over 1–8 weeks with subsequent dose maintenance for 4 weeks. Early-morning motor function and nocturnal sleep disturbance were assessed as coprimary efficacy endpoints using the Unified Parkinson's Disease Rating Scale (UPDRS) Part III (Motor Examination) measured in the early morning prior to any medication intake and the modified Parkinson's Disease Sleep Scale (PDSS-2) (mean change from baseline to end of maintenance [EOM], last observation carried forward). At EOM, mean UPDRS Part III score had decreased by −7.0 points with rotigotine (from a baseline of 29.6 [standard deviation (SD) 12.3] and by −3.9 points with placebo (baseline 32.0 [13.3]). Mean PDSS-2 total score had decreased by −5.9 points with rotigotine (from a baseline of 19.3 [SD 9.3]) and by −1.9 points with placebo (baseline 20.5 [10.4]). This represented a significantly greater improvement with rotigotine compared with placebo on both the UPDRS Part III (treatment difference: −3.55 [95% confidence interval (CI) −5.37, −1.73]; P = 0.0002) and PDSS-2 (treatment difference: −4.26 [95% CI −6.08, −2.45]; P < 0.0001). The most frequently reported adverse events were nausea (placebo, 9%; rotigotine, 21%), application site reactions (placebo, 4%; rotigotine, 15%), and dizziness (placebo, 6%; rotigotine 10%). Twenty-four-hour transdermal delivery of rotigotine to PD patients with early-morning motor dysfunction resulted in significant benefits in control of both motor function and nocturnal sleep disturbances. © 2010 Movement Disorder Society

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.

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.