Rotigotine transdermal system for the treatment of Parkinson's disease

Dissolving microarray patches loaded with a rotigotine nanosuspension: A potential alternative to Neupro® patch

Parkinson's disease (PD), affecting about ten million people globally, presents a significant health challenge. Rotigotine (RTG), a dopamine agonist, is currently administered as a transdermal patch (Neupro®) for PD treatment, but the daily application can be burdensome and cause skin irritation. This study introduces a combinatorial approach of dissolving microarray patch (MAP) and nanosuspension (NS) for the transdermal delivery of RTG, offering an alternative to Neupro®. The RTG-NS was formulated using a miniaturized media milling method, resulting in a nano-formulation with a mean particle size of 274.09 ± 7.43 nm, a PDI of 0.17 ± 0.04 and a zeta potential of -15.24 ± 2.86 mV. The in vitro dissolution study revealed an enhanced dissolution rate of the RTG-NS in comparison to the coarse RTG powder, under sink condition. The RTG-NS MAPs, containing a drug layer and a 'drug-free' supporting baseplate, have a drug content of 3.06 ± 0.15 mg/0.5 cm2 and demonstrated greater amount of drug delivered per unit area (∼0.52 mg/0.5 cm2) than Neupro® (∼0.20 mg/1 cm2) in an ex vivo Franz cell study using full-thickness neonatal porcine skin. The in vivo pharmacokinetic studies demonstrated that RTG-NS MAPs, though smaller (2 cm2 for dissolving MAPs and 6 cm2 for Neupro®), delivered drug levels comparable to Neupro®, indicating higher efficiency per unit area. This could potentially avoid unnecessarily high plasma levels after the next dose at 24 h, highlighting the benefits of dissolving MAPs over conventional transdermal patches in PD treatment.

Poly(acrylic acid)/Poly(vinyl alcohol) Microarray Patches for Continuous Transdermal Delivery of Levodopa and Carbidopa: In Vitro and In Vivo Studies

Levodopa (LD) has been the most efficacious medication and the gold standard therapy for Parkinson's disease (PD) for decades. However, its long-term administration is usually associated with motor complications, which are believed to be the result of the fluctuating pharmacokinetics of LD following oral administration. Duodopa® is the current option to offer a continuous delivery of LD and its decarboxylase inhibitor carbidopa (CD); however, its administration involves invasive surgical procedures, which could potentially lead to lifelong complications, such as infection. Recently, dissolving microarray patches (MAPs) have come to the fore as an alternative that can bypass the oral administration route in a minimally invasive way. This work explored the potential of using dissolving MAPs to deliver LD and CD across the skin. An acidic polymer poly(acrylic acid) (PAA) was used in the MAP fabrication to prevent the potential oxidation of LD at neutral pH. The drug contents of LD and CD in the formulated dissolving MAPs were 1.82 ± 0.24 and 0.47 ± 0.04 mg/patch, respectively. The in vivo pharmacokinetic study using female Sprague-Dawley® rats (Envigo RMS Holding Corp, Bicester, UK) demonstrated a simultaneous delivery of LD and CD and comparable AUC values between the dissolving MAPs and the oral LD/CD suspension. The relative bioavailability for the dissolving MAPs was calculated to be approximately 37.22%. Accordingly, this work highlights the use of dissolving MAPs as a minimally invasive approach which could potentially bypass the gastrointestinal pathway and deliver both drugs continuously without surgery.

Recent advances in dopamine D2 receptor ligands in the treatment of neuropsychiatric disorders

Dopamine is a biologically active amine synthesized in the central and peripheral nervous system. This biogenic monoamine acts by activating five types of dopamine receptors (D_1-5 Rs), which belong to the G protein-coupled receptor family. Antagonists and partial agonists of D₂ Rs are used to treat schizophrenia, Parkinson's disease, depression, and anxiety. The typical pharmacophore with high D₂ R affinity comprises four main areas, namely aromatic moiety, cyclic amine, central linker and aromatic/heteroaromatic lipophilic fragment. From the literature reviewed herein, we can conclude that 4-(2,3-dichlorophenyl), 4-(2-methoxyphenyl)-, 4-(benzo[b]thiophen-4-yl)-1-substituted piperazine, and 4-(6-fluorobenzo[d]isoxazol-3-yl)piperidine moieties are critical for high D₂ R affinity. Four to six atoms chains are optimal for D₂ R affinity with 4-butoxyl as the most pronounced one. The bicyclic aromatic/heteroaromatic systems are most frequently occurring as lipophilic appendages to retain high D₂ R affinity. In this review, we provide a thorough overview of the therapeutic potential of D₂ R modulators in the treatment of the aforementioned disorders. In addition, this review summarizes current knowledge about these diseases, with a focus on the dopaminergic pathway underlying these pathologies. Major attention is paid to the structure, function, and pharmacology of novel D₂ R ligands, which have been developed in the last decade (2010-2021), and belong to the 1,4-disubstituted aromatic cyclic amine group. Due to the abundance of data, allosteric D₂ R ligands and D₂ R modulators from patents are not discussed in this review.

Dopamine D3 Receptor in Parkinson Disease: A Prognosis Biomarker and an Intervention Target

Parkinson disease (PD) dementia, pathologically featured as nigrostriatal dopamine (DA) neuronal loss with motor and non-motor manifestations, leads to substantial disability and economic burden. DA therapy targets the DA D3 receptor (D3R) with high affinity and selectivity. The pathological involvement of D3R is evidenced as an effective biomarker for disease progression and DA agnostic interventions, with compensations of increased DA, decreased aggregates of α-synuclein (α-Syn), enhanced secretion of brain-derived neurotrophic factors (BDNF), attenuation of neuroinflammation and oxidative damage, and promoting neurogenesis in the brain. D3R also interacts with D1R to reduce PD-associated motor symptoms and alleviate the side effects of levodopa (L-DOPA) treatment. We recently found that DA D2 receptor (D2R) density decreases in the late-stage PDs, while high D3R or DA D1 receptor (D1R) + D3R densities in the postmortem PD brains correlate with survival advantages. These new essential findings warrant renewed investigations into the understanding of D3R neuron populations and their cross-sectional and longitudinal regulations in PD progression.

Antinociceptive effects of rotigotine-loaded microspheres and its synergistic interactions with analgesics in inflammatory pain in rats

Rotigotine-loaded microspheres (RoMS) are sustained-release formulations with prolonged anti-Parkinson's effects. Given that pain is a non-motor symptom of Parkinson's disease, this study investigated the antinociceptive effects of RoMS and their synergistic effects with analgesics on inflammatory pain. A model of inflammatory pain was prepared by intraplantarly injecting male Sprague-Dawley rats with carrageenan. The antinociceptive effects of RoMS, acetaminophen, and tramadol, both alone and in combination, were evaluated using the hind paw withdrawal latency in the hot plate test and Randall-Selitto test. The rotigotine concentrations in serum and tissues were assayed using ultra-performance liquid chromatography-tandem mass spectrometry. Isobolographic analysis was performed to evaluate the nature of the interactions of RoMS with acetaminophen or tramadol. The results showed that hind paw withdrawal latency to thermal and mechanical stimuli was significantly increased on day 3 and 7 after administered RoMS. Rotigotine could be detected in serum and tissues 3 and 7 days after an intramuscular injection of RoMS. However, the rotigotine concentration fell the detection limit of the assay on day 14 after administration. RoMS produced synergistic antinociceptive effects in the inflammatory pain model when RoMS is combined with acetaminophen or tramadol. These findings suggest that RoMS can relieve inflammatory pain in rats. Furthermore, the combination of RoMS with acetaminophen or tramadol produces synergistic antinociception, which may be clinically worthy because combination therapies may reduce the drug doses required for antinociception.

Social listening - revealing Parkinson's disease over day and night

Background

Nocturnal symptoms in Parkinson’s disease are often treated after management of daytime manifestations. In order to better understand the unmet needs of nocturnal symptoms management, we analyzed the characteristics and burden of nocturnal symptoms from patients’ perspectives and explored their changes over time. Overall symptoms (occurring at day or night) were collected to compare whether the unmet needs related to nocturnal symptoms and to overall symptoms are different.

Methods

We used a Social Listening big-data technique to analyze large amounts of Parkinson’s disease symptoms in dialogues available from social media platforms in 2016 to 2018. These symptoms were classified as either overall symptoms or nocturnal symptoms. We used share of voice (SOV) of symptoms as a proportion of total dialogues per year to reflect the characteristics of symptoms. Negative sentiment score of symptoms was analyzed to find out their related burden.

Results

We found the SOV for overall motor symptoms was 79% and had not increased between 2016 and 2018 (79%, p = 0.5). The SOV for non-motor symptoms was 69% and had grown by 7% in 2018 (p <  0.01). The SOV for motor complications was 9% and had increased by 6% in 2018 (p <  0.01). The SOV of motor symptoms was larger than non-motor symptoms and motor complications (p <  0.01). The SOV of non-motor symptoms was larger than motor complications (p <  0.01). For nocturnal symptoms, 45% of the analyzed PD population reported nocturnal symptoms in 2018, growing by 6% (p <  0.01). The SOV for nocturnal-occurring motor symptoms was higher than most non-motor symptoms. However, non-motor symptoms had the higher increases and evoked higher negative sentiment regardless of whether they occurred during the day or night. For symptoms that can occur at either day or night, each nocturnal symptom was rated with a higher negative sentiment score than the same symptom during the day.

Conclusions

The growing SOV and the greater negative sentiment of nocturnal symptoms suggest management of nocturnal symptoms is an unmet need of patients. A greater emphasis on detecting and treating nocturnal symptoms with 24-h care is encouraged.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-020-02024-4.

Evolution of phosphorus-thioether ligands for asymmetric catalysis

In the early 1990s chiral P-thiother ligands emerged as promising ligands in the field of asymmetric catalysis, with the development of many P-thioether ligand families. However, only a few of them have shown a broad reaction and substrate scope. So, compared with other heterodonor ligands such as the widely studied P-N ligands, their impact in asymmetric catalysis was not realised until recently. This has been mainly attributed to the difficulty of controlling the configuration at the sulfur atom when coordinated to the metal. More recently, it has been found that this problem could be solved by a rigorous choice of the ligand scaffold, a process usually aided by mechanistic studies. This allowed the recent discovery of new P-thioether ligand families with a broader versatility, both in reactions and in substrate/reagent scope. This feature article aims to highlight those new P-thioether ligand libraries and the relationship between the structure and catalytic performance.

Dopamine D3 receptor: A neglected participant in Parkinson Disease pathogenesis and treatment?

Parkinson disease (PD) is a neurodegenerative disorder characterized by motor and non-motor symptoms which relentlessly and progressively lead to substantial disability and economic burden. Pathologically, these symptoms follow the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) associated with abnormal α-synuclein (α-Syn) deposition as cytoplasmic inclusions called Lewy bodies in pigmented brainstem nuclei, and in dystrophic neurons in striatal and cortical regions (Lewy neurites). Pharmacotherapy for PD focuses on improving quality of life and primarily targets dopaminergic pathways. Dopamine acts through two families of receptors, dopamine D1-like and dopamine D2-like; dopamine D3 receptors (D3R) belong to dopamine D2 receptor (D2R) family. Although D3R's precise role in the pathophysiology and treatment of PD has not been determined, we present evidence suggesting an important role for D3R in the early development and occurrence of PD. Agonist activation of D3R increases dopamine concentration, decreases α-Syn accumulation, enhances secretion of brain derived neurotrophic factors (BDNF), ameliorates neuroinflammation, alleviates oxidative stress, promotes neurogenesis in the nigrostriatal pathway, interacts with D1R to reduce PD associated motor symptoms and ameliorates side effects of levodopa (L-DOPA) treatment. Furthermore, D3R mutations can predict PD age of onset and prognosis of PD treatment. The role of D3R in PD merits further research. This review elucidates the potential role of D3R in PD pathogenesis and therapy.

Ir–Biaryl phosphite–oxazoline catalyst libraries: a breakthrough in the asymmetric hydrogenation of challenging olefins

This work describes our progress in the successful development of phosphite/phosphinite–oxazoline ligands for the Ir-catalyzed asymmetric hydrogenation of challenging olefins.

Recent trends in the transdermal delivery of therapeutic agents used for the management of neurodegenerative diseases

With the increasing proportion of the global geriatric population, it becomes obvious that neurodegenerative diseases will become more widespread. From an epidemiological standpoint, it is necessary to develop new therapeutic agents for the management of Alzheimer's disease, Parkinson's disease, multiple sclerosis and other neurodegenerative disorders. An important approach in this regard involves the use of the transdermal route. With transdermal drug delivery systems (TDDS), it is possible to modulate the pharmacokinetic profiles of these medications and improve patient compliance. Transdermal drug delivery has also been shown to be useful for drugs with short half-life and low or unpredictable bioavailability. In this review, several transdermal drug delivery enhancement technologies are being discussed in relation to the delivery of medications used for the management of neurodegenerative disorders.

Ibuprofen or piroxicam protects nigral neurons and delays the development of l-dopa induced dyskinesia in rats with experimental Parkinsonism: Influence on angiogenesis

Neuroinflammation and angiogenesis have been involved in the pathogenesis of Parkinson's disease (PD). This study investigated the effect of ibuprofen or piroxicam on the motor response to l-dopa and development of dyskinesia in Parkinsonian rats focusing on the anti-angiogenic role of the two non-steroidal anti-inflammatory drugs (NSAIDs). Rats were divided into nine groups as follows: Group I: the vehicle group, Group II: rotenone group, rats were injected with nine doses of rotenone (1 mg/kg/48 h), group III&IV: rats received rotenone + ibuprofen (10 or 30 mg/kg), Group V-VI: rats received rotenone + piroxicam (1 or 3 mg/kg), Group VII: rats received rotenone + l-dopa/carbidopa (100/10 mg/kg), Group VIII-IX: rats received rotenone + l-dopa/carbidopa + ibuprofen (30 mg/kg) or piroxicam (3 mg/kg). In general, drugs were administered daily for ten weeks. Rotenone-treated rats showed motor dysfunction, lower striatal dopamine, lower staining for nigral tyrosine hydroxylase but higher level of striatal cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) compared to vehicle-treated rats (P < 0.05). Treatment with l-dopa showed wearing-off over the course of the experiment in addition to development of abnormal involuntary movements and upregulated striatal VEGF level. Treatment with ibuprofen or piroxicam in combination with l-dopa preserved the effect of l-dopa at the end of week 10, delayed the development of dyskinesia and decreased striatal COX-2 and VEGF levels. In conclusion, the current study suggests that ibuprofen and piroxicam are promising candidates for neuroprotection in PD and may have utility in conjunction with l-dopa in order to ensure the longevity of its action and to delay the development of dyskinesia.

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.

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.

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.

Therapeutic options for continuous dopaminergic stimulation in Parkinson's disease

Treatment of Parkinson's disease aims to replace dopaminergic transmission at striatal synapses. In the normal state, nigral neurons fire continuously, exposing striatal dopamine receptors to relatively constant levels of dopamine. In the disease state, periodic dosing and the short half-life of antiparkinsonian drugs leads to more intermittent stimulation. Abnormal pulsatile stimulation of striatal dopamine receptors may lead to dysregulation of genes and proteins in downstream neurons and consequently, alterations in neuronal firing patterns. This may ultimately lead to motor complications. In order to prevent the development of motor complications a therapy that provides continuous dopaminergic stimulation as observed in the normal state would be ideal. Different routes of administration of levodopa and other dopaminergic drugs have been tried to achieve continuous dopaminergic stimulation (CDS). This review discusses the various methods available to achieve this goal with particular emphasis on duodenal dopa administration.

Dopaminergic agonists in Parkinson's disease

BACKGROUND

Non-ergoline dopamine agonists (DA) are effective treatments for Parkinson's disease (PD). This review presents the pharmacology, evidence of efficacy and safety profile of pramipexole, ropinirole, and rotigotine, and practical recommendations are given regarding their use in clinical practice.

RESULTS

Extended-release formulations of pramipexole and ropinirole and transdermal continuous delivery rotigotine patches are currently available; these may contribute to stabilising of plasma levels. In early PD, the three drugs significantly improve disability scales, delay time to dyskinesia and allow a later introduction of levodopa. In late PD they reduced total 'off'-time, improved Unified Parkinson's Disease Rating Scale (UPDRS) in both 'on' and 'off' state and allowed a reduction in total levodopa dosage. A significant improvement in quality of life scales has also been demonstrated. Extended-release formulations have proved to be non-inferior to the immediate release formulations and are better tolerated (ropinirole). Despite a generally good safety profile, serious adverse events, such as impulse control disorder and sleep attacks, need to be routinely monitored. Although combination therapy has not been addressed in scientific literature, certain combinations, such as apomorphine and another DA, may be helpful. Switching from one DA to another is feasible and safe, although in the first days an overlap of dopaminergic side effects may occur. When treatment with DA is stopped abruptly, dopamine withdrawal syndrome may present. Suspending any DA, especially pramipexole, has been linked to onset of apathy, which may be severe.

CONCLUSIONS

New non-ergotine DAs are a valuable option for the treatment of both early and late PD. Despite their good safety profile, serious adverse effects may appear; these effects may have a pathoplastic effect on the course of PD and need to be monitored.

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

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.

Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 February 2008 and 31 January 2009 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.

Rotigotine transdermal delivery for the treatment of Parkinson's disease

BACKGROUND

Rotigotine is a non-ergot dopamine agonist that has been developed as a new transdermal formulation, and is indicated for use in early (USA and Europe) and advanced (Europe only) Parkinson's disease (PD). The potential advantages of the rotigotine patch include immediacy of effect onset as intestinal absorption in unneeded, constant drug delivery, and ease of use via application of a once-daily adhesive patch. An interesting element of this profile is constant drug delivery, which may avoid pulsatile dopaminergic stimulation, which has been postulated to be related to the development of motor complications.

OBJECTIVE

To consider the evidence surrounding the profile of rotigotine and, in particular, whether its constant delivery system offers significant benefits to the treatment of early and advanced PD.

METHODS

Source material was identified using a PubMed search for the term 'rotigotine' (up to March 2008). The review focuses only on publications related to the rotigotine indication for PD.

RESULTS/CONCLUSION

The rotigotine transdermal patch demonstrates clinical efficacy, alongside a tolerability profile that appears to be well within the range of that observed with other non-ergot dopamine agonists. The once-daily patch formulation may favour compliance but, in similarity with the other theoretical advantages of constant drug delivery (for example reduced emergence of motor complications, improved tolerance to peripheral AEs), requires further detailed study.

A review of ropinirole prolonged release in Parkinson's disease

Ropinirole prolonged release is a once-daily, 24-hour formulation of ropinirole, a non-ergot dopamine agonist. It is approved as monotherapy and as an adjunct to levodopa in the treatment of Parkinson's disease (PD). Several potential advantages of ropinirole prolonged release compared to the immediate release formulation include maintaining more consistent dopaminergic activity with steadier plasma levels, increased tolerability, greater compliance from a simpler once-daily dosing regimen and ease in dose titration. In a randomized, double-blind, non-inferiority, crossover study, ropinirole prolonged release was shown to have comparable efficacy and tolerability to immediate release ropinirole in early PD patients, with significantly greater compliance. Subjects were converted overnight between ropinirole formulations without loss of efficacy and with good tolerability. In a randomized, double-blind, placebo-controlled study in advanced PD, daily "off" time was reduced by an average of 2.1 hours with ropinirole prolonged release compared to 0.4 hours with placebo. Patients on ropinirole prolonged release were also more likely to require less daily levodopa. Ropinirole prolonged release is well tolerated with a similar adverse effect profile to other non-ergot dopamine agonists. The most common adverse effects include dyskinesia, nausea, dizziness, hallucinations, somnolence, abdominal pain or discomfort and orthostatic hypotension. Ropinirole prolonged release is a safe and effective treatment option for both early and advanced PD. This manuscript briefly reviews the current pharmacological treatment options for PD and provides a more detailed review of the currently available data regarding ropinirole prolonged release as a treatment option for PD.