Levodopa: A new look at an old friend

Dopamine and its precursor levodopa inactivate SARS-CoV-2 main protease by forming a quinoprotein

Many studies show either the absence, or very low levels of, SARS-CoV-2 viral RNA and/or antigen in the brain of COVID-19 patients. Reports consistently indicate an abortive infection phenomenon in nervous cells despite the fact that they contain the SARS-CoV-2 receptor, ACE2. Dopamine levels in different brain regions are in the range of micromolar to millimolar concentrations. We have shown that sub-micromolar to low micromolar concentrations of dopamine or its precursor (levodopa) time- and dose-dependently inhibit the activity of SARS-CoV-2 main protease (Mpro), which is vital for the viral life cycle, by forming a quinoprotein. Thiol detection coupled with the assessment of Mpro activity suggests that among the 12 cysteinyl thiols, the active site, Cys145-SH, is preferentially conjugated to the quinone derived from the oxidation of dopamine or levodopa. LC-MS/MS analyses show that the Cys145-SH is covalently conjugated by dopamine- or levodopa-o-quinone. These findings help explain why SARS-CoV-2 causes inefficient replication in many nerve cell lines. It is well recognized that inhaled pulmonary drug delivery is the most robust therapy pathway for lung diseases. CVT-301 (orally inhaled levodopa) was approved by the FDA as a drug for Parkinson's patients prior to the outbreak of COVID-19 in 2018. Based on the fact that SARS-CoV-2 causes inefficient replication in the CNS with abundant endogenous Mpro inhibitor in addition to the current finding that levodopa has an Mpro-inhibitory effect somewhat stronger than dopamine, we should urgently investigate the use of CVT-301 as a lung-targeting, COVID-19, Mpro inhibitor.

Pathological cell assembly dynamics in a striatal MSN network model

Under normal conditions the principal cells of the striatum, medium spiny neurons (MSNs), show structured cell assembly activity patterns which alternate sequentially over exceedingly long timescales of many minutes. It is important to understand this activity since it is characteristically disrupted in multiple pathologies, such as Parkinson's disease and dyskinesia, and thought to be caused by alterations in the MSN to MSN lateral inhibitory connections and in the strength and distribution of cortical excitation to MSNs. To understand how these long timescales arise we extended a previous network model of MSN cells to include synapses with short-term plasticity, with parameters taken from a recent detailed striatal connectome study. We first confirmed the presence of sequentially switching cell clusters using the non-linear dimensionality reduction technique, Uniform Manifold Approximation and Projection (UMAP). We found that the network could generate non-stationary activity patterns varying extremely slowly on the order of minutes under biologically realistic conditions. Next we used Simulation Based Inference (SBI) to train a deep net to map features of the MSN network generated cell assembly activity to MSN network parameters. We used the trained SBI model to estimate MSN network parameters from ex-vivo brain slice calcium imaging data. We found that best fit network parameters were very close to their physiologically observed values. On the other hand network parameters estimated from Parkinsonian, decorticated and dyskinetic ex-vivo slice preparations were different. Our work may provide a pipeline for diagnosis of basal ganglia pathology from spiking data as well as for the design pharmacological treatments.

Safety and efficacy of continuous subcutaneous levodopa-carbidopa infusion (ND0612) for Parkinson's disease with motor fluctuations (BouNDless): a phase 3, randomised, double-blind, double-dummy, multicentre trial

BACKGROUND

Conventional oral levodopa therapy for the treatment of Parkinson's disease can be associated with variations in plasma concentrations. Levodopa infusion strategies might provide more consistent drug delivery and fewer motor fluctuations. We aimed to assess the safety and efficacy of a continuous 24 h/day subcutaneous infusion of ND0612 (a levodopa-carbidopa solution) compared with oral immediate-release levodopa-carbidopa for the treatment of motor fluctuations in people with Parkinson's disease.

METHODS

We conducted a phase 3, randomised, double-blind, double-dummy, active-controlled, multicentre trial at 117 academic and community neurology sites in 16 countries, including in Europe, Israel, and the USA. Eligible participants were men and women aged 30 years or older with a diagnosis of Parkinson's disease (Hoehn and Yahr stage ≤3 in the on state) who experienced at least 2·5 h/day of off time. Participants underwent an open-label run-in phase (<12 weeks), during which time optimal regimens were established for both oral immediate-release levodopa-carbidopa and for 24 h/day subcutaneous ND0612 infusion (levodopa-carbidopa 60·0/7·5 mg/mL), with supplemental oral levodopa-carbidopa if needed. Participants were then randomly assigned (1:1) to 12 weeks of double-blind treatment with their optimised regimen of either subcutaneous ND0612 or oral levodopa-carbidopa, with matching oral or subcutaneous placebo given as required to maintain blinding. Randomisation was done via an interactive web response system, stratified by region, using a permuted block schedule. Participants, study partners, treating investigators, study site personnel, and the sponsor were masked to treatment group allocation. The primary efficacy endpoint was the change from baseline (ie, time of randomisation, when all patients were receiving an optimised open-label ND0612 regimen) to end of the double-blind phase in total daily on time without troublesome dyskinesia, analysed by intention to treat. This trial is registered with ClinicalTrials.gov, NCT04006210, and is complete.

FINDINGS

Between Sept 30, 2019, and April 8, 2022, 381 participants were enrolled, of whom 259 (68%) were randomly assigned, 128 (49%) to subcutaneous ND0612 and 131 (51%) to oral levodopa-carbidopa. 243 (94%) participants completed the study. Treatment with subcutaneous ND0612 provided an additional 1·72 h (95% CI 1·08 to 2·36) of on time without troublesome dyskinesia compared with oral levodopa-carbidopa (change from baseline of -0·48 h [-0·94 to -0·02] with subcutaneous ND0612 vs -2·20 h [-2·65 to -1·74] with oral levodopa-carbidopa; p<0·0001). Significant treatment differences favouring subcutaneous ND0612 were also found in the first four of nine prespecified hierarchical outcomes of daily off time (-1·40 h [95% CI -1·99 to -0·80]), Movement Disorders Society-Unified Parkinson's Disease Rating Scale part II scores (-3·05 [-4·28 to -1·81]), Patients Global Impression of Change (odds ratio [OR] 5·31 [2·67 to 10·58]), and Clinical Global Impression of Improvement (OR 7·23 [3·57 to 14·64]). Hierarchical testing ended after the fourth secondary endpoint. Adverse events were reported by 287 (89%) of 322 participants during open-label ND0612 optimisation, and by 103 (80%) of 128 in the ND0612 group and 97 (74%) of 131 in the oral levodopa-carbidopa group during the double-blind phase. The most common adverse events were infusion-site reactions (266 [83%] participants during open-label ND0612, and 73 [57%] in the ND0612 group vs 56 [43%] in the oral levodopa-carbidopa group during the double-blind phase), most of which were mild. Serious adverse events in four participants in the ND0612 group were related to study treatment (infusion-site cellulitis [n=2], infusion-site abscess and infusion-site ulcer [n=1]; and paraesthesia and peripheral sensorimotor neuropathy [n=1]). One participant in the ND0612 group died during the double-blind phase, but the death was not related to study treatment (fall leading to traumatic brain injury).

INTERPRETATION

Results of this phase 3 study showed that subcutaneous ND0612 used in combination with oral immediate-release levodopa-carbidopa increased on time without troublesome dyskinesia and reduced off time, with a favourable benefit-risk profile. ND0612 might offer a safe and efficacious subcutaneous levodopa infusion approach to managing motor fluctuations in people with Parkinson's disease. The ongoing open-label extension phase will provide further information on the long-term efficacy and safety of treatment.

FUNDING

NeuroDerm.

Real-world evidence on levodopa dose escalation in patients with Parkinson's disease treated with istradefylline

OBJECTIVE

Istradefylline, a selective adenosine A2A receptor antagonist, is indicated in the US and Japan as adjunctive treatment to levodopa/decarboxylase inhibitors in adults with Parkinson's disease (PD) experiencing OFF time. This study aimed to observe patterns of dose escalation of levodopa over time in patients initiated on istradefylline.

METHODS

Using Japanese electronic health record data, interrupted time series analyses were used to compare levodopa daily dose (LDD, mg/day) gradients in patients before and after initiation of istradefylline. Data were analyzed by period relative to istradefylline initiation (Month 1): pre-istradefylline (Months -72 to 0), early istradefylline (Months 1 to 24), and late istradefylline (Months 25 to 72). Subgroup analyses included LDD before istradefylline initiation (<400, ≥400 to <600, ≥600 mg/day) and treatment with or without monoamine oxidase-B (MAO-B) inhibitors, catechol-O-methyltransferase (COMT) inhibitors, or dopamine agonists before istradefylline initiation.

RESULTS

The analysis included 4026 patients; mean (SD) baseline LDD was 419.27 mg (174.19). Patients receiving ≥600 mg/day levodopa or not receiving MAO-B inhibitors or COMT inhibitors demonstrated a significant reduction in LDD increase gradient for pre-istradefylline vs late-phase istradefylline (≥600 mg/day levodopa, -6.259 mg/day each month, p<0.001; no MAO-B inhibitors, -1.819 mg/day each month, p = 0.004; no COMT inhibitors, -1.412 mg/day each month, p = 0.027).

CONCLUSIONS

This real-world analysis of Japanese prescription data indicated that slowing of LDD escalation was observed in patients initiated on istradefylline, particularly in those receiving ≥600 mg/day levodopa, suggesting istradefylline may slow progressive LDD increases. These findings suggest that initiating istradefylline before other levodopa-adjunctive therapies may mitigate LDD increases, potentially reducing occurrence or severity of levodopa-induced complications in long-term istradefylline treatment.

Adopting the Rumsfeld approach to understanding the action of levodopa and apomorphine in Parkinson's disease

Dopaminergic therapies dominate the treatment of the motor and non-motor symptoms of Parkinson's disease (PD) but there have been no major advances in therapy in many decades. Two of the oldest drugs used appear more effective than others-levodopa and apomorphine-but the reasons for this are seldom discussed and this may be one cause for a lack of progress. This short review questions current thinking on drug action and looks at whether adopting the philosophy of ex-US Secretary of State Donald Rumsfeld reveals 'unknown' aspects of the actions of levodopa and apomorphine that provide clues for a way forward. It appears that both levodopa and apomorphine have a more complex pharmacology than classical views would suggest. In addition, there are unexpected facets to the mechanisms through which levodopa acts that are either forgotten as 'known unknowns' or ignored as 'unknown unknowns'. The conclusion reached is that we may not know as much as we think about drug action in PD and there is a case for looking beyond the obvious.

Drug repurposing of dopaminergic drugs to inhibit ataxin-3 aggregation

The accumulation of mutant ataxin-3 (Atx3) in neuronal nuclear inclusions is a pathological hallmark of Machado-Joseph disease (MJD), also known as Spinocerebellar Ataxia Type 3. Decreasing the protein aggregation burden is a possible disease-modifying strategy to tackle MJD and other neurodegenerative disorders for which only symptomatic treatments are currently available. We performed a drug repurposing screening to identify inhibitors of Atx3 aggregation with known toxicological and pharmacokinetic profiles. Interestingly, dopamine hydrochloride and other catecholamines are among the most potent inhibitors of Atx3 aggregation in vitro. Our results indicate that low micromolar concentrations of dopamine markedly delay the formation of mature amyloid fibrils of mutant Atx3 through the inhibition of the earlier oligomerization steps. Although dopamine itself does not cross the blood-brain barrier, dopamine levels in the brain can be increased by low doses of dopamine precursors and dopamine agonists commonly used to treat Parkinsonian symptoms. In agreement, treatment with levodopa ameliorated motor symptoms in a C. elegans model of MJD. These findings suggest a possible application of dopaminergic drugs to halt or reduce Atx3 accumulation in the brains of MJD patients.

Inhaled levodopa for threatening impending OFF episodes in managing Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder that leads to the degeneration of dopaminergic neurons resulting in a widespread pathology of motor and non-motor symptoms. Oral levodopa remains the most effective symptomatic treatment of PD, but motor complications such as Off episodes occur over time. The spectrum of manifestation of OFF episodes varies, e.g., early morning akinesia, end-of-dose wearing OFF, delayed ON, suboptimal ON and dose failure. The functional disability substantially impacts the quality of life for PD patients. An innovative on-demand therapy to treat Off episodes was approved for patients receiving oral levodopa/dopa deacarboxylase inhibitor: inhaled levodopa powder (Inbrija®). The pulmonary delivery of inhaled levodopa powder provides a predictable and fast treatment effect, independent of gastrointestinal dysfunctions or food intake, which could affect levodopa absorption. Levodopa is administered with a breath-actuated inhaler device and the approved dose is 84 mg per Off episode. During the pivotal SPAN-PD phase III trial, significant improvement in Unified Parkinson Disease Rating Scale III score was measured 30 min post-dose at week 12. Improvement was already seen for the first measured time point 10 min post-dose. No differences in pulmonary function was observed when using inhaled levodopa powder regularly for up to 12 months. Inhaled levodopa powder was also approved for early morning Off episodes. The aim of this review article is to give an overview of the different clinical studies of the innovative inhaled levodopa powder, a new on-demand therapy to treat Off episodes in PD.

Impact of Sex on Neuroimmune contributions to Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease. Inflammation has been observed in both the idiopathic and familial forms of PD. Importantly, PD is reported more often in men than in women, men having at least 1.5- fold higher risk to develop PD than women. This review summarizes the impact of biological sex and sex hormones on the neuroimmune contributions to PD and its investigation in animal models of PD. Innate and peripheral immune systems participate in the brain neuroinflammation of PD patients and is reproduced in neurotoxin, genetic and alpha-synuclein based models of PD. Microglia and astrocytes are the main cells of the innate immune system in the central nervous system and are the first to react to restore homeostasis in the brain. Analysis of serum immunoprofiles in female and male control and PD patients show that a great proportion of these markers differ between male and female. The relationship between CSF inflammatory markers and PD clinical characteristics or PD biomarkers shows sex differences. Conversely, in animal models of PD, sex differences in inflammation are well documented and the beneficial effects of endogenous and exogenous estrogenic modulation in inflammation have been reported. Targeting neuroinflammation in PD is an emerging therapeutic option but gonadal drugs have not yet been investigated in this respect, thus offering new opportunities for sex specific treatments.

Serotonin 5-HT1A receptors and their interactions with adenosine A2A receptors in Parkinson's disease and dyskinesia

The dopamine neuronal loss that characterizes Parkinson's Disease (PD) is associated to changes in neurotransmitters, such as serotonin and adenosine, which contribute to the symptomatology of PD and to the onset of dyskinetic movements associated to levodopa treatment. The present review describes the role played by serotonin 5-HT_1A receptors and the adenosine A_2A receptors on dyskinetic movements induced by chronic levodopa in PD. The focus is on preclinical and clinical results showing the interaction between serotonin 5-HT_1A receptors and other receptors such as 5-HT_1B receptors and adenosine A_2A receptors. 5-HT_1A/1B receptor agonists and A_2A receptor antagonists, administered in combination, contrast dyskinetic movements induced by chronic levodopa without impairing motor behaviour, suggesting that this drug combination might be a useful therapeutic approach for counteracting the PD motor deficits and dyskinesia associated with chronic levodopa treatment. This article is part of the Special Issue on "The receptor-receptor interaction as a new target for therapy".

Three-Dimensional Analysis of Sex- and Gonadal Status- Dependent Microglial Activation in a Mouse Model of Parkinson’s Disease

Parkinson’s disease (PD) is characterized by neurodegeneration and neuroinflammation. PD prevalence and incidence are higher in men than in women and modulation of gonadal hormones could have an impact on the disease course. This was investigated in male and female gonadectomized (GDX) and SHAM operated (SHAM) mice. Dutasteride (DUT), a 5α-reductase inhibitor, was administered to these mice for 10 days to modulate their gonadal sex hormones. On the fifth day of DUT treatment, mice received 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to model PD. We have previously shown in these mice the toxic effect of MPTP in SHAM and GDX males and in GDX females on dopamine markers and astrogliosis whereas SHAM females were protected by their female sex hormones. In SHAM males, DUT protected against MPTP toxicity. In the present study, microglial density and the number of doublets, representative of a microglial proliferation, were increased by the MPTP lesion only in male mice and prevented by DUT in SHAM males. A three-dimensional morphological microglial analysis showed that MPTP changed microglial morphology from quiescent to activated only in male mice and was not prevented by DUT. In conclusion, microgliosis can be modulated by sex hormone-dependent and independent factors in a mice model of PD.

Levodopa Carbidopa Intestinal Gel in Advanced Parkinson's Disease: DUOGLOBE Final 3-Year Results

BACKGROUND

Levodopa-carbidopa intestinal gel (LCIG) improves motor and non-motor symptoms in patients with advanced Parkinson's disease (aPD).

OBJECTIVE

To present the final 36-month efficacy and safety results from DUOGLOBE (DUOdopa/Duopa in Patients with Advanced Parkinson's Disease - a GLobal OBservational Study Evaluating Long-Term Effectiveness; NCT02611713).

METHODS

DUOGLOBE was an international, prospective, long-term, real-world, observational study of patients with aPD initiating LCIG in routine clinical care. The primary endpoint was change in patient-reported "Off" time to Month 36. Safety was assessed by monitoring serious adverse events (SAEs).

RESULTS

Significant improvements in "Off" time were maintained over 3 years (mean [SD]: -3.3 hours [3.7]; p < 0.001). There were significant improvements to Month 36 in total scores of the Unified Dyskinesia Rating Scale (-5.9 [23.7]; p = 0.044), Non-Motor Symptoms Scale (-14.3 [40.5]; p = 0.002), Parkinson's Disease Sleep Scale-2 (-5.8 [12.9]; p < 0.001), and Epworth Sleepiness Scale (-1.8 [6.0]; p = 0.008). Health-related quality of life and caregiver burden significantly improved through Months 24 and 30, respectively (Month 24, 8-item Parkinson's Disease Questionnaire Summary Index, -6.0 [22.5]; p = 0.006; Month 30, Modified Caregiver Strain Index, -2.3 [7.6]; p = 0.026). Safety was consistent with the well-established LCIG profile (SAEs: 54.9% of patients; discontinuations: 54.4%; discontinuations due to an adverse event: 27.2%). Of 106 study discontinuations, 32 patients (30.2%) continued LCIG outside the study.

CONCLUSION

DUOGLOBE demonstrates real-world, long-term, reductions in motor and non-motor symptoms in patients with aPD treated with LCIG.

Association of Depression With Early Occurrence of Postural Instability in Parkinson's Disease

OBJECTIVE

Depression in Parkinson's disease (PD) affects the quality of life of patients. Postural instability and gait disturbance are associated with the severity and prognosis of PD. We investigated the association of depression with axial involvement in early-stage PD patients.

METHODS

This study involved 95 PD patients unexposed to antiparkinsonian drugs. After a baseline assessment for depression, the subjects were divided into a depressed PD group and a nondepressed PD group. Analyses were conducted to identify an association of depression at baseline with the following outcome variables: the progression to Hoehn and Yahr scale (H-Y) stage 3, the occurrence of freezing of gait (FOG), levodopa-induced dyskinesia, and wearing-off. The follow-up period was 53.40 ± 16.79 months from baseline.

RESULTS

Kaplan-Meier survival curves for H-Y stage 3 and FOG showed more prominent progression to H-Y stage 3 and occurrences of FOG in the depressed PD group than in the nondepressed PD group (log-rank p = 0.025 and 0.003, respectively). Depression in drug-naïve, early-stage PD patients showed a significant association with the progression to H-Y stage 3 (hazard ratio = 2.55; 95% confidence interval = 1.32-4.93; p = 0.005), as analyzed by Cox regression analyses. In contrast, the occurrence of levodopa-induced dyskinesia and wearing-off did not differ between the two groups (log-rank p = 0.903 and 0.351, respectively).

CONCLUSION

Depression in drug-naïve, early-stage PD patients is associated with an earlier occurrence of postural instability. This suggests shared nondopaminergic pathogenic mechanisms and potentially enables the prediction of early development of postural instability.

Sex Is the Main Determinant of Levodopa Clinical Pharmacokinetics: Evidence from a Large Series of Levodopa Therapeutic Monitoring

BACKGROUND

Different studies, mostly with limited cohorts, have suggested the effects of patients' characteristics on levodopa (LD) pharmacokinetics.

OBJECTIVE

We primarily aimed at investigating in a large population the relationship between patients' features and LD kinetic variables, to assess the main demographic and clinical predictors of LD clinical pharmacokinetics.

METHODS

The study was retrospective, based on data collected from subjects with parkinsonism on chronic LD undergoing LD therapeutic monitoring (TM). LD TM includes serial quantitative motor tests and blood samples to measure plasma drug concentrations after each subject's chronically taken first-morning LD dose intake.

RESULTS

Five hundred patients, 308 males (61.6%), mean (SD) age of 65 (10.1) years were included. Parkinsonian symptoms and LD therapy lasted 5.5 (4.5) and 3.4 (3.9) years, respectively. MDS-UPDRS part III "off" score was 28.8 (15.2). LD dose was 348.2 (187.1) mg/day. From multiple linear regression analysis, test dose, sex, type of LD decarboxylase inhibitor, weight and MDS-UPDRS part III score were linear predictors of both LD peak plasma concentration (Cmax) (R2 = 0.52) and area under the 3-h plasma concentration-time curve (AUC) (R2 = 0.71), while age was a further predictor only for AUC. Besides test dose, sex was the strongest independent contributing variable to LD AUC, which resulted 27% higher in females compared to males.

CONCLUSION

This is the largest collection of data on the relationship between demographic and clinical-therapeutic variables and LD kinetics in patients with parkinsonian symptoms. As a main clinically practical finding, women might require a 25% reduced weight-normalized LD dose compared with men to achieve the same LD bioavailability.

Tailoring Motor Fluctuation Treatment: Beyond Levodopa Dose Adjustment

Susan Fox opened this satellite symposium at the 8th European Academy of Neurology (EAN) Congress with an overview of the concept of motor fluctuations (MF) in Parkinson’s disease (PD). She emphasised that levodopa remains the gold standard therapy for PD. However, MFs are one of the critical complications of levodopa therapy that affect many patients with advancing PD and, when diagnosed, represent a challenge in patient management. Alternative options are, therefore, needed to provide continuous dopaminergic stimulation while maximising the levodopa benefit. Despite different options, Angelo Antonini showed that neurologists often prefer to adjust levodopa dose rather than add an adjunctive agent. Market research confirms that, in patients with PD, the levodopa dose is adjusted in around 80% of patients, while only 20% have adjunct therapy as a first-line option. Adjusting the levodopa dose, either by increasing or fractionating the dose, or both, remains a valid, tried-and-tested option, although it has limitations. Joaquim Ferreira presented emerging evidence from a Phase II clinical trial, suggesting a potential benefit of adding opicapone 50 mg compared with 100 mg levodopa to treat patients with PD and end-of-dose fluctuations. This symposium aimed to present the effect of opicapone with relatively low total daily doses of levodopa; an option that may not have been traditionally considered by neurologists who are used to adjusting levodopa as a first-line response.

Nanomedicine in the Face of Parkinson's Disease: From Drug Delivery Systems to Nanozymes

The complexity and overall burden of Parkinson's disease (PD) require new pharmacological approaches to counteract the symptomatology while reducing the progressive neurodegeneration of affected dopaminergic neurons. Since the pathophysiological signature of PD is characterized by the loss of physiological levels of dopamine (DA) and the misfolding and aggregation of the alpha-synuclein (α-syn) protein, new proposals seek to restore the lost DA and inhibit the progressive damage derived from pathological α-syn and its impact in terms of oxidative stress. In this line, nanomedicine (the medical application of nanotechnology) has achieved significant advances in the development of nanocarriers capable of transporting and delivering basal state DA in a controlled manner in the tissues of interest, as well as highly selective catalytic nanostructures with enzyme-like properties for the elimination of reactive oxygen species (responsible for oxidative stress) and the proteolysis of misfolded proteins. Although some of these proposals remain in their early stages, the deepening of our knowledge concerning the pathological processes of PD and the advances in nanomedicine could endow for the development of potential treatments for this still incurable condition. Therefore, in this paper, we offer: (i) a brief summary of the most recent findings concerning the physiology of motor regulation and (ii) the molecular neuropathological processes associated with PD, together with (iii) a recapitulation of the current progress in controlled DA release by nanocarriers and (iv) the design of nanozymes, catalytic nanostructures with oxidoreductase-, chaperon, and protease-like properties. Finally, we conclude by describing the prospects and knowledge gaps to overcome and consider as research into nanotherapies for PD continues, especially when clinical translations take place.

A Randomized Thorough QT Study of Apomorphine Sublingual Film in Patients With Parkinson's Disease

A randomized thorough QT study was conducted to assess the effects of apomorphine sublingual film (SL-APO) on corrected QT interval (QTc) and other cardiac conduction parameters in patients with Parkinson's disease (PD) and "OFF" episodes. Patients were titrated to an SL-APO dose that resulted in FULL "ON," followed by up to two additional doses (maximum 60 mg), then randomized at the highest tolerated dose to a treatment sequence of SL-APO, placebo, and moxifloxacin (400 mg, positive control) in a three-way crossover design. Changes from baseline in time-matched, placebo-adjusted Fridericia-corrected QTc interval (ΔΔQTcF) and Bazett-corrected QTc interval (ΔΔQTcB) were analyzed from postdose electrocardiograms. Forty patients were randomized and received single doses of study treatments. Upper limits of 90% confidence intervals (CIs) for ΔΔQTcF of SL-APO were below the 10-millisecond regulatory threshold at all prespecified timepoints, demonstrating no clinically significant effect on QTcF. Lower limits of 90% CIs for ΔΔQTcF of moxifloxacin exceeded the 5-millisecond regulatory threshold at all timepoints up to 3 hours, confirming assay sensitivity. SL-APO had no clinically meaningful effects on QTcB, PR/QRS intervals, heart rate, or electrocardiogram-derived morphology (EudraCT identifier: 2016-001762-29; ClinicalTrials.gov identifier: NCT03187301).

Multimodal detection of dopamine by sniffer cells expressing genetically encoded fluorescent sensors

Dopamine supports locomotor control and higher brain functions such as motivation and learning. Consistently, dopaminergic dysfunction is involved in a spectrum of neurological and neuropsychiatric diseases. Detailed data on dopamine dynamics is needed to understand how dopamine signals translate into cellular and behavioral responses, and to uncover pathological disturbances in dopamine-related diseases. Genetically encoded fluorescent dopamine sensors have recently enabled unprecedented monitoring of dopamine dynamics in vivo. However, these sensors' utility for in vitro and ex vivo assays remains unexplored. Here, we present a blueprint for making dopamine sniffer cells for multimodal dopamine detection. We generated sniffer cell lines with inducible expression of seven different dopamine sensors and perform a head-to-head comparison of sensor properties to guide users in sensor selection. In proof-of-principle experiments, we apply the sniffer cells to record endogenous dopamine release from cultured neurons and striatal slices, and for determining tissue dopamine content. Furthermore, we use the sniffer cells to measure dopamine uptake and release via the dopamine transporter as a radiotracer free, high-throughput alternative to electrochemical- and radiotracer-based assays. Importantly, the sniffer cell framework can readily be applied to the growing list of genetically encoded fluorescent neurotransmitter sensors.

Blueberry juice augments exercise-induced neuroprotection in a Parkinson's disease model through modulation of GDNF levels

Exercise and consumption of plant-based foods rich in polyphenols are attractive therapeutic approaches for the prevention and treatment of Parkinson's disease (PD). Few studies, however, have examined the neuroprotective efficacy of combining these treatment modalities against PD. Therefore we investigated whether combining voluntary running and consumption of blueberry juice (BBJ) was more efficacious against 6-hydroxydopamine (6-OHDA) toxicity than either treatment alone. Four weeks of running before and after intrastriatal 6-OHDA reduced amphetamine-induced rotational behavior and loss of substantia nigra dopamine (DA) neurons. BBJ consumption alone had no ameliorative effects, but when combined with exercise, behavioral deficits and nigrostriatal DA neurodegeneration were reduced to a greater extent than exercise alone. The neuroprotection observed with exercise alone was associated with an increase in striatal glial cell-lined derived neurotrophic factor (GDNF), whereas combining exercise and BBJ was associated with an increase in nigral GDNF. These results suggest that polyphenols may potentiate the protective effects of exercise and that differential regulation of GDNF expression underlies protection observed with exercise alone versus combined treatment with consumption of BBJ.

Striatal neuronal ensembles reveal differential actions of amantadine and clozapine to ameliorate mice L-DOPA-induced dyskinesia

Amantadine and clozapine have proved to reduce abnormal involuntary movements (AIMs) in preclinical and clinical studies of L-DOPA-Induced Dyskinesias (LID). Even though both drugs decrease AIMs, they may have different action mechanisms by using different receptors and signaling profiles. Here we asked whether there are differences in how they modulate neuronal activity of multiple striatal neurons within the striatal microcircuit at histological level during the dose-peak of L-DOPA in ex-vivo brain slices obtained from dyskinetic mice. To answer this question, we used calcium imaging to record the activity of dozens of neurons of the dorsolateral striatum before and after drugs administration in vitro. We also developed an analysis framework to extract encoding insights from calcium imaging data by quantifying neuronal activity, identifying neuronal ensembles by linking neurons that coactivate using hierarchical cluster analysis and extracting network parameters using Graph Theory. The results show that while both drugs reduce LIDs scores behaviorally in a similar way, they have several different and specific actions on modulating the dyskinetic striatal microcircuit. The extracted features were highly accurate in separating amantadine and clozapine effects by means of principal components analysis (PCA) and support vector machine (SVM) algorithms. These results predict possible synergistic actions of amantadine and clozapine on the dyskinetic striatal microcircuit establishing a framework for a bioassay to test novel antidyskinetic drugs or treatments in vitro.

Prevention of L-Dopa-Induced Dyskinesias by MPEP Blockade of Metabotropic Glutamate Receptor 5 Is Associated with Reduced Inflammation in the Brain of Parkinsonian Monkeys

Proinflammatory markers were found in brains of Parkinson’s disease (PD) patients. After years of L-Dopa symptomatic treatment, most PD patients develop dyskinesias. The relationship between inflammation and L-Dopa-induced dyskinesias (LID) is still unclear. We previously reported that MPEP (a metabotropic glutamate receptor 5 antagonist) reduced the development of LID in de novo MPTP-lesioned monkeys. We thus investigated if MPEP reduced the brain inflammatory response in these MPTP-lesioned monkeys and the relationship to LID. The panmacrophage/microglia marker Iba1, the phagocytosis-related receptor CD68, and the astroglial protein GFAP were measured by Western blots. The L-Dopa-treated dyskinetic MPTP monkeys had increased Iba1 content in the putamen, substantia nigra, and globus pallidus, which was prevented by MPEP cotreatment; similar findings were observed for CD68 contents in the putamen and globus pallidus. There was a strong positive correlation between dyskinesia scores and microglial markers in these regions. GFAP contents were elevated in MPTP + L-Dopa-treated monkeys among these brain regions and prevented by MPEP in the putamen and subthalamic nucleus. In conclusion, these results showed increased inflammatory markers in the basal ganglia associated with LID and revealed that MPEP inhibition of glutamate activity reduced LID and levels of inflammatory markers.

Impact of a Collaborative Pharmaceutical Care Service for Patients With Parkinson's Disease

Objective: To identify the impact of a collaborative pharmaceutical care service (CPCS) on medication safety and establish the impact of the CPCS on patient reported outcomes for Parkinson's disease (PD) patients. Methods: Initially, PD outpatients receiving the CPCS between March 2017 and March 2019 were compared with PD patients receiving standard of care to identify differences in management. Pharmacist interventions data were coded and patients with PD receiving the CPCS were compared with those receiving standard of care to determine differences in medicines prescribed and dosage associated with these. Following this, data of patients receiving CPCS at baseline and 3-months follow-up were collected using a questionnaire consisting of validated measures of two patient-reported outcomes [adherence and quality of life (QoL)]. Mean scores for continuous variables were calculated, with descriptive analysis of categorical variables consisting of frequency counts and percentages. Change in adherence score before and after CPCS was investigated using a Wilcoxon sign rank sum test, spearman correlation analysis was used to correlate the changes in QoL before and after CPCS with the number of interventions, and p < 0.05 indicates that the difference is statistically significant. Results: A total of 331 PD outpatients received CPCS over 490 outpatient visits with an average age of 71.83 (±12.54). Five hundred and forty-five drug related problems were recorded as pharmacist interventions, of which most involved change to dosage (n = 226, 41.47%), adverse drug reactions (n = 135, 24.77%), and change in a medication (n = 102, 18.72%). Compared with those receiving standard of care, patients receiving CPCS were significantly less likely to have been prescribed pramipexole (18.52 versus 23.77%, p < 0.001) and more likely to have been prescribed amantadine (5.40 versus 3.70%, p = 0.02) and selegiline (17.36 versus 11.64%, p < 0.001). Lower dosages of levodopa/benserazide (0.51 ± 0.31 g versus 0.84 ± 0.37 g, p < 0.001), levodopa/carbidopa (0.33 ± 0.23 g versus 0.66 ± 0.47 g, p < 0.001), pramipexole (1.14 ± 1.63 mg versus 1.27 ± 0.69 mg, p = 0.01), and entacapone (130.00 ± 79.76 mg versus 173.09 ± 97.86 mg, p < 0.001) were also recorded. At baseline 119 PD outpatients with an average age of 69.98 (±9.90) were recruited for the longitudinal study. At 3-month follow-up, participants reported improvement in bodily pain subscale (baseline versus 3-months follow-up, 30.04 ± 22.21 versus 23.01 ± 20.98, p = 0.037) and medication adherence (6.19 ± 1.50 versus 6.72 ± 1.73, p = 0.014). Frequency of CPCS use was related to activity of daily living subscale (p = 0.047), the bodily pain subscale (p = 0.026), and medication adherence (p = 0.011). Total score of PDQ-39 was associated with patient education (p = 0.005) and usage and dosage combined with patient education (p = 0.006), while medication adherence score was associated with usage and dosage (p = 0.005). Conclusion: The CPCS was effective in resolving drug-related problems and in improving patients' medication regimens, medication adherence, and QoL through patient education and dosage adjustments. This is the first step in the development and feasibility testing of pharmacy services for PD patients in China.

Targeting the non-classical estrogen pathway in neurodegenerative diseases and brain injury disorders

Estrogens can alter the biology of various tissues and organs, including the brain, and thus play an essential role in modulating homeostasis. Despite its traditional role in reproduction, it is now accepted that estrogen and its analogues can exert neuroprotective effects. Several studies have shown the beneficial effects of estrogen in ameliorating and delaying the progression of neurodegenerative diseases, including Alzheimer's and Parkinson's disease and various forms of brain injury disorders. While the classical effects of estrogen through intracellular receptors are more established, the impact of the non-classical pathway through receptors located at the plasma membrane as well as the rapid stimulation of intracellular signaling cascades are still under active research. Moreover, it has been suggested that the non-classical estrogen pathway plays a crucial role in neuroprotection in various brain areas. In this mini-review, we will discuss the use of compounds targeting the non-classical estrogen pathway in their potential use as treatment in neurodegenerative diseases and brain injury disorders.

Effect of sex and gonadectomy on brain MPTP toxicity and response to dutasteride treatment in mice

The main neuropathological feature of Parkinson's disease (PD) is degeneration of dopamine (DA) neurons in the substantia nigra (SN); PD prevalence is higher in men, suggesting a role of sex hormones in neuroprotection. This study sought the effects of sex hormones in the brain in a mouse model of PD and modulation of steroid metabolism/synthesis with the 5α-reductase inhibitor dutasteride shown to protect 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) male mice. Male and female mice were gonadectomized (GDX) or SHAM operated. They were treated with vehicle or dutasteride (5 mg/kg) for 10 days and administered a low dose of MPTP (5.5 mg/kg) or saline on the 5th day to model early PD; brains were collected thereafter. Striatal measures of the active metabolite 1-methyl-4-phenylpyridinium (MPP+) contents showed no difference supporting an effect of the experimental conditions investigated. In SHAM MPTP male mice loss of striatal DA and metabolites, DA transporter (DAT) and vesicular monoamine transporter 2 (VMAT2) specific binding in the striatum and SN was prevented by dutasteride treatment; these changes were inversely correlated with glial fibrillary acidic protein (GFAP, an astrogliosis marker) levels. In SHAM female mice MPTP treatment had little or no effect on striatal and SN DA markers and GFAP levels whereas GDX male and female mice showed a similar loss of striatal DA markers and increase of GFAP. No effect of dutasteride treatment was observed in GDX male and female mice. In conclusion, sex differences in mice MPTP toxicity and response to dutasteride were observed that were lost upon gonadectomy implicating neuroinflammation.

Glucocerebrosidase (GBA) gene variants in a multi-ethnic Asian cohort with Parkinson's disease: mutational spectrum and clinical features

GBA variants are associated with increased risk and earlier onset of Parkinson's disease (PD), and more rapid disease progression especially with "severe" variants typified by p.L483P. GBA mutation screening studies from South-East Asia, with > 650 million inhabitants of diverse ancestries, are very limited. We investigated the spectrum of GBA variants, and associated clinico-demographic features, in a multi-ethnic PD cohort in Malaysia. Patients (n = 496) were recruited from seven centres, primarily of Chinese (45%), Malay (37%), and Indian (13%) ethnicities. All GBA coding exons were screened using a next-generation sequencing-based PD gene panel and verified with Sanger sequencing. We identified 14 heterozygous GBA alleles consisting of altogether 17 missense variants (8 classified as pathogenic or likely pathogenic for PD) in 25 (5.0%) patients, with a substantially higher yield among early (< 50 years) vs. late-onset patients across all three ethnicities (9.1-13.2% vs. 1.0-3.2%). The most common variant was p.L483P (including RecNciI, n = 11, 2.2%), detected in all three ethnicities. Three novel variants/recombinant alleles of uncertain significance were found; p.P71L, p.L411P, and p.L15S(;)S16G(;)I20V. The common European risk variants, p.E365K, p.T408M, and p.N409S, were not detected. A severe disease course was noted in the majority of GBA-variant carriers, across a range of detected variants. We report a potentially novel observation of spine posture abnormalities in GBA-variant carriers. This represents the largest study on GBA variation from South-East Asia, and highlights that these populations, especially those with EOPD, would be relevant for studies including clinical trials targeting GBA pathways.

Temporal dynamics of cortical activity and postural control in response to the first levodopa dose of the day in people with Parkinson's disease

BACKGROUND

Our understanding of how balance control responds to levodopa over the course of a single day in people with Parkinson's disease (PD) is limited with the majority of studies focused on isolated comparisons of ON vs. OFF levodopa medication.

OBJECTIVE

To evaluate the temporal dynamics of postural control following the first levodopa dose of the day during a challenging standing task in a group of people with PD.

METHODS

Changes in postural control were evaluated by monitoring cortical activity (covering frontal, motor, parietal and occipital areas), body sway parameters (force platform), and lower limb muscle activity (tibialis anterior and gastrocnemius medialis) in 15 individuals with PD during a semi-tandem standing task. Participants were assessed during two 60 second trials every 30 minutes (ON-30 ON-60 etc.) for 3 hours after the first matinal dose (ON-180).

RESULTS

Compared to when tested OFF-medication, cortical activity was increased across all four regions from ON-60 to ON-120 with early increases in alpha and beta band activity observed at ON-30. Levodopa was associated with increased gastrocnemius medialis activity (ON-30 to ON-120) and ankle co-contraction (ON-60 to ON-120). Changes in body sway outcomes (particularly in the anterior-posterior direction) were evident from ON-60 to ON-120.

CONCLUSIONS

Our results reveal a 60-minute window within which postural control outcomes may be obtained that are different compared to OFF-state and remain stable (from 60-minutes to 120-minutes after levodopa intake). Identifying a window of opportunity for measurement when individuals are optimally medicated is important for observations in a clinical and research setting.

Dose optimization of apomorphine sublingual film for treating "OFF" episodes in Parkinson's disease

INTRODUCTION

Apomorphine sublingual film is approved for the "on-demand" treatment of "OFF" episodes in Parkinson's disease (PD). Patients must undergo dose titration to determine their most effective and tolerable dose. We assessed whether higher doses than those that provide an initial "ON" response could yield more effective treatment.

METHODS

Patients with PD were assessed in the "OFF" state and the apomorphine sublingual film dose was titrated to a level that provided a tolerable "ON" response. The dose was then increased by up to two dose levels, if tolerated. A comparison in the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III scores was made following administration of the dose that provided the initial "ON" response and following the higher dose. Treatment-emergent adverse events were also reported.

RESULTS

Thirty-five patients were titrated to higher apomorphine sublingual film doses than those that provided an initial "ON" response. A mean improvement in MDS-UPDRS Part III score was observed compared with the initial dose of 5.6 points (P = 0.034), 4.4 points (P = 0.009), and 3.7 points (P = 0.018) at 30, 60, and 90 min postdose, respectively. Adverse events were mild or moderate and resolved with dose reduction without concomitant treatment.

CONCLUSION

Higher doses of apomorphine sublingual film than those initially perceived to provide an "ON" response can be tolerated and provide additional improvement in motor function in many patients.

A technology evaluation of CVT-301 (Inbrija): an inhalable therapy for treatment of Parkinson's disease

Introduction: The most widely used pharmacological treatment for Parkinson's disease is levodopa, the precursor for dopamine formation in the brain. Over time, the effectiveness of levodopa declines, and patients experience motor fluctuations, or OFF periods. A levodopa formulation administered via a capsule-based oral inhaler provides a new delivery mechanism for levodopa that provides rapid relief of OFF periods.Areas covered: CVT-301 is a dry powder formulation designed to supply levodopa to the systemic circulation via pulmonary absorption. The technology, pharmacokinetics, efficacy, and safety data of this formulation are presented.Expert opinion: Oral inhalation is a novel method of administration for levodopa that bypasses the gastrointestinal tract, allowing levodopa to enter the systemic circulation rapidly and more reliably than oral medications. Gastrointestinal dysfunction, a common feature of Parkinson's disease, can lead to impaired absorption of oral medications. Pulmonary delivery rapidly elevates levodopa plasma concentrations to provide relief of OFF periods for patients receiving oral levodopa.

Effect of catechin and commercial preparation of green tea essence on the pharmacokinetics of l-dopa in rabbits

The aim of this study was to investigate drug interactions of L-dopa/carbidopa with catechin and green tea essence in rabbits following the simultaneous administration via an intramuscular injection of catechin or via an intragastric route for green tea essence with L-dopa/carbidopa. The results indicated that catechin at doses of 10, 20 and 50 mg/kg increased the area under the plasma concentration-time curve from time zero to the time of the last quantifiable concentration (AUC_0-t ) of L-dopa by about 69, 78 and 42%, respectively. The metabolic ratios of the AUC_0-t for 3-O-methyldopa (3-OMD)/L-dopa significantly decreased by about 56, 68 and 76% (P < 0.05), respectively. In addition, a single dose of 5/1.25 mg/kg L-dopa/carbidopa was co-administrated with 150 mg/kg green tea essence via an intragastric route with an oral-gastric tube. Comparing the related pharmacokinetic parameters of L-dopa, the clearance and metabolic ratio of L-dopa decreased by 20 and 19% (P < 0.05), respectively. In conclusion, catechin and green tea essence can significantly affect the metabolism of L-dopa by the catechol-O-methyltransferase (COMT) metabolic pathway. Catechin can enhance L-dopa bioavailability, and both catechin and green tea essence decreased 3-OMD formation. Therefore, catechin and green tea essence may increase L-dopa efficacy for Parkinson's disease treatment.

On-Demand Therapy for OFF Episodes in Parkinson's Disease

Levodopa is the most effective therapy for Parkinson's disease; however, chronic treatment is associated with the development of OFF episodes, in which there is a return of parkinsonian features following a dose of levodopa and prior to the onset of benefit from the subsequent dose. OFF episodes can be a major source of disability for PD patients and frequently result in depression, apathy and an unwillingness to participate in social activities. Most currently available medical and surgical therapies are designed to reduce total daily OFF time but do not provide a rapid and reliable "on-demand" therapy for individual OFF episodes. Indeed, responses to individual doses of levodopa during an acute OFF episode are unreliable, frequently leading to partial-ON, delayed-ON, or no-ON responses even at different times in the same patient. There are now 3 therapies that are available for the on-demand treatment of OFF episodes; subcutaneous injection of apomorphine, sublingual apomorphine film, and inhaled levodopa. The first has not enjoyed widespread use in the PD community, whereas the latter 2 therapies have only recently been approved. This review will consider the currently available on-demand therapies and their potential advantages and disadvantages. © 2021 International Parkinson and Movement Disorder Society.

Pharmacokinetics and Comparative Bioavailability of Apomorphine Sublingual Film and Subcutaneous Apomorphine Formulations in Patients with Parkinson's Disease and "OFF" Episodes: Results of a Randomized, Three-Way Crossover, Open-Label Study

Introduction

In a pivotal study, apomorphine sublingual film (APL; KYNMOBI^®) was an effective and generally well-tolerated on-demand treatment of “OFF” episodes in patients with Parkinson’s disease (PD), approved across the dose range of 10–30 mg. Pharmacokinetics and comparative bioavailability of APL and two subcutaneous (SC) apomorphine formulations (SC-APO [APOKYN^®] and SC-APO-GO [APO-go^® PEN]) were evaluated in a randomized, three-way crossover, open-label study (NCT03292016).

Methods

Patients with PD and “OFF” episodes received an open-label randomized sequence of single doses of SC-APO and SC-APO-GO at the currently prescribed dose (2/3/4/5 mg) and APL doses with similar plasma exposure (15/20/25/30 mg) with ≥ 1-day washout between formulations. Plasma pharmacokinetics of apomorphine and apomorphine sulfate (major inactive metabolite) were measured 0–6 h postdose.

Results

Median time to maximum plasma concentration (t_max) of apomorphine was 0.63–0.75 h for APL and 0.25–0.38 h for SC-APO and SC-APO-GO. Geometric mean maximum plasma concentration (C_max) of apomorphine was 4.31–11.2 ng/ml across APL doses and was generally lower compared with SC apomorphine formulations within dose groups. Area under the concentration-time curve from time 0 to infinity (AUC_∞) was similar across apomorphine formulations within most dose groups. Relative bioavailability of APL was ~ 17% of SC apomorphine by AUC_∞; SC-APO and SC-APO-GO had similar bioavailability (98% and 83% by AUC_∞ and C_max, respectively). Apomorphine sulfate exposure was ~ three-fold higher for APL versus SC-APO and SC-APO-GO by AUC_∞ and C_max.

Conclusion

In patients with PD and “OFF” episodes, APL demonstrated lower C_max and relative bioavailability but similar exposures (AUCs) versus SC apomorphine within the approved dose range.

Trial Registration

ClinicalTrials.gov, NCT03292016.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-021-00251-6.

Population pharmacokinetic analysis of apomorphine sublingual film or subcutaneous apomorphine in healthy subjects and patients with Parkinson's disease

Apomorphine is an on-demand treatment of "OFF" episodes in patients with Parkinson's disease (PD). A joint parent-metabolite population pharmacokinetic (PK) model characterized apomorphine and apomorphine-sulfate following administration of apomorphine sublingual film (APL) and two formulations of subcutaneous apomorphine. Overall, 2485 samples from 87 healthy subjects and 71 patients with PD and "OFF" episodes were analyzed using nonlinear mixed-effects modeling. Apomorphine PK was adequately described by a two-compartment model with first-order transit absorption via both routes of administration and first-order metabolism to apomorphine-sulfate with one-compartment disposition and first-order elimination. Bioavailability of apomorphine sublingual film was ~ 18% relative to subcutaneous apomorphine. Among covariates tested, only body weight had a large effect on apomorphine exposure (maximum plasma concentration and area under the concentration-time curve [AUC_0-∞ ]), with greater weight resulting in lower exposure. Model-predicted apomorphine exposure was similar between apomorphine sublingual film 30 mg and subcutaneous apomorphine 5 mg (median AUC_0-24 , 66.7 ng•h/mL, geometric mean ratio of 0.99; 90% confidence interval [CI], 0.96-1.03) and was comparable between apomorphine sublingual film 35 mg and subcutaneous apomorphine 6 mg (median AUC_0-24 , 75.4 and 80.0 ng•h/mL, respectively; geometric mean ratio of 0.94; 90% CI, 0.90-0.97) administered every 2 h for a maximum of 5 doses per day. In a typical patient with PD, predicted apomorphine exposure increased with increasing doses of apomorphine sublingual film; however, the increase was less than dose proportional. Similar apomorphine exposure was predicted in patients with mild renal impairment versus normal renal function. PK properties of apomorphine sublingual film support its administration for a wide range of patients with PD and "OFF" episodes, regardless of demographic and clinical characteristics.

Quantitative Assessment of Motor Response to a Low Subacute Levodopa Dose in the Differential Diagnosis of Parkinsonisms at Disease Onset: Data from the BoProPark Cohort

Background:

Differential diagnosis between Parkinson’s disease (PD) and atypical parkinsonisms (APs) may be difficult at disease onset. The response to levodopa (LD) is a key supportive feature but its definition is largely empirical. Studies evaluating this issue by quantitative tests are scanty.

Objective:

We aimed to assess the utility of a subacute low LD dose kinetic-dynamic test in the differential diagnosis between PD and APs. It was applied at the baseline of a prospective follow-up in patients with parkinsonian signs within three years of disease motor onset (“BoProPark” cohort) and eventually diagnosed as PD or APs according to consensus criteria.

Methods:

Patients under at least 3-month LD therapy received a first morning fasting dose of LD/benserazide or carbidopa (100/25 mg) and underwent simultaneous serial assessments of plasma LD concentration and alternate finger tapping frequency up to 3 h. The main outcome was the extent of LD motor response, calculated by the area under the 3 h tapping effect–time curve (AUC_ETap). A receiver operating characteristic (ROC) curve analysis was performed to establish the optimal AUC_ETap cut-off to differentiate PD and APs.

Results:

The first 100 consecutive “BoProPark” patients were analyzed. Forty-seven patients were classified as possible, 37 as probable PD and 16 as APs. AUC_ETap medians were similar in the PD subgroups but reduced to a third in APs (p < 0.001). The optimal AUC_ETap cut-off value was >2186 [(tap/min) x min], with a sensitivity of 92% and a specificity of 75%. Accuracy of the test was 0.85 (95% CI 0.74–0.95), p < 0.0001.

Conclusion:

The estimation of 3 h AUC_ETap after a subacute low LD dose proved a reliable, objective tool to assess LD motor response in our cohort of patients. AUC_ETap value rounded to ≥2200 supports PD diagnosis, while lower values may alert to AP diagnoses.

An evaluation of the efficacy and value of CVT-301 for the treatment of Parkinson's disease

Introduction: Levodopa is the most effective drug in the treatment of Parkinson's disease, but its chronic treatment is linked to the occurrence of motor complications with fluctuations of motor performance and dyskinesia. Unpredictable OFF episodes can be severe and disabling and current rescue medications cannot always be used safely. Rescue therapy is characterized by a rapid and predictable ON response and the safety profile of levodopa will represent a major advantage for patients affected by unresponsive OFF episodes.Areas covered: CVT-301 is a new inhaled formulation of LD recently developed as a self-administered treatment for OFF periods. Herein, the pharmacodynamic and pharmacokinetic properties, efficacy, and safety of CVT-301 are reviewed.Expert opinion: CVT-301 may offer several potential advantages including increased systemic bioavailability through pulmonary absorption, rapid onset of action, avoidance of first-pass drug metabolism, and less plasma level variability. It should be noted that the delivery device used has been described as relatively simple to use, but the few steps required to prepare and self-administer the dose can be challenging for PD patients during their OFF state. Additionally, resolution of an OFF episode requires the administration of two capsules of CVT-301, which further complicates the use of the device.

Advancing Personalized Medicine in Common Forms of Parkinson's Disease through Genetics: Current Therapeutics and the Future of Individualized Management

Parkinson’s disease (PD) is a condition with heterogeneous clinical manifestations that vary in age at onset, rate of progression, disease course, severity, motor and non-motor symptoms, and a variable response to antiparkinsonian drugs. It is considered that there are multiple PD etiological subtypes, some of which could be predicted by genetics. The characterization and prediction of these distinct molecular entities provides a growing opportunity to use individualized management and personalized therapies. Dissecting the genetic architecture of PD is a critical step in identifying therapeutic targets, and genetics represents a step forward to sub-categorize and predict PD risk and progression. A better understanding and separation of genetic subtypes has immediate implications in clinical trial design by unraveling the different flavors of clinical presentation and development. Personalized medicine is a nascent area of research and represents a paramount challenge in the treatment and cure of PD. This manuscript summarizes the current state of precision medicine in the PD field and discusses how genetics has become the engine to gain insights into disease during our constant effort to develop potential etiological based interventions.

Imaging the Functional Neuroanatomy of Parkinson's Disease: Clinical Applications and Future Directions

The neurobiology of Parkinson’s disease and its progression has been investigated during the last few decades. Braak et al. proposed neuropathological stages of this disease based on the recognizable topographical extent of Lewy body lesions. This pathological process involves specific brain areas with an ascending course from the brain stem to the cortex. Post-mortem studies are of importance to better understand not only the progression of motor symptoms, but also the involvement of other domains, including cognition and behavior. The correlation between the neuropathological expansion of the disease and the clinical phases remains demanding. Neuroimaging, including magnetic resonance imaging (MRI), positron emission tomography (PET), and single photon emission computed tomography (SPECT), could help to bridge this existing gap by providing in vivo evidence of the extension of the disorders. In the last decade, we observed an overabundance of reports regarding the sensitivity of neuroimaging techniques. All these studies were aimed at improving the accuracy of Parkinson’s disease (PD) diagnosis and discriminating it from other causes of parkinsonism. In this review, we look at the recent literature concerning PD and address the new frontier of diagnostic accuracy in terms of identification of early stages of the disease and conventional neuroimaging techniques that, in vivo, are capable of photographing the basal ganglia network and its cerebral connections.

Factors affecting the choice of first-line therapy in Parkinson's disease patients in Wales: A population-based study

First line treatment for Parkinson’s disease (PD) is typically either L-dopa or a non-ergot dopamine agonist (DA). However, the options for the treatment of motor symptoms in PD patients have increased in the last thirty years, which have seen several new classes of PD medications introduced onto the market. The purpose of this study is to examine the changes in first line therapy of newly diagnosed Parkinson’s patients between 2000 and 2016 in Wales.

A population-based study evaluated data from the Secure Anonymised Information Linkage (SAIL) Databank of residents in Wales, aged 40 years or older, newly treated with PD medications between 2000 and 2016. The data was compared across three intervals: 2000–2005, 2006–2011 and 2012–2016. Patients were classified by age at diagnosis into young: 40–60 years; mid, 61–80 years; and older >80 years. Logistic regression was undertaken to determine the predictors of PD medication prescribing.

For the whole study period, the profiles of 9142 newly diagnosed PD patients were analysed. L-dopa was the most common first line therapy (80.6%), followed by non-ergot DAs (12.9%) and monoamine oxidase B (MAO-B) inhibitors (7.9%). Odds of L-dopa prescribing were greater in patients >80 years (OR = 20.46 95%CI: 16.25–25.76) and in the period 2012–2016 (OR = 1.98 95% CI: 1.70–2.29). Prescribing of non-ergot DAs significantly declined in 2012–2016 (OR = 0.42 95% CI: 0.35–0.49). Additional factors influencing first line therapy were deprivation, presence of diabetes and prior use of antidepressants. For example, PD patients residing in the least deprived area were less likely to be prescribed L-dopa compared to patients residing in the most deprived area (OR = 0.77 95% CI: 0.65–0.93).

First line therapy in PD in Wales has undergone a significant switch towards L-dopa over the last 16 years. The data indicates reasonable compliance with guidelines on efficacy and safety issues related to Parkinson’s medications.

The clinical meaning of levodopa equivalent daily dose in Parkinson's disease

Levodopa (L-dopa) remains the basis of pharmacological treatment of Parkinson's disease (PD). However, L-dopa therapy is associated with the development of complications and presents major challenges in the long-term treatment. Thus, other medications may be suggested to delay and/or reduce the doses of L-dopa in order to prevent complications. The interpretation of treatment evolution reported in clinical trials on PD may be tricky, especially due to some variability in medications and dose regimens. Some authors have suggested a conversion factor to generate a total L-dopa equivalent daily dose (LEDD), calculated as a sum of each parkinsonian medication. Therefore, LEDD provides an artificial summary of the total daily medication a patient is receiving, and to date, there is no report focusing on the clinical interpretation of this parameter. Thus, based on a 3-year, multi-center retrospective study assessing the impact of second-line therapy initiation on LEDD in PD patients, the aim of our article was to discuss LEDD as a quantitative outcome to estimate the impact of second-line therapies on medication regimens; and in the second part of the discussion, to provide a narrative review of the clinical outcomes associated with LEDD in the literature.

History of and Insights Into Spinal Cord Stimulation in Parkinson Disease

BACKGROUND

Current available therapies for Parkinson disease (PD) have strong limitations, and patients usually present with refractory symptoms despite all efforts. Deep brain stimulation (DBS), which has been used in PD patients for decades (since 1987), has best indications for symptoms like tremor, motor fluctuations, or dyskinesia. However, postural instability and gait disturbances (PIGD) have restricted benefits with DBS. In 2009, spinal cord stimulation (SCS), a well-established therapy for chronic pain, has emerged as a potential alternative therapy that may help control unresponsive symptoms such as bradykinesia, PIGD, and freezing of gait.

METHODS

The main studies regarding SCS in PD are reviewed here from the first studies in animal models to the latest clinical trials.

CONCLUSIONS

Despite promising findings, the heterogeneity of methodologies used and small samples in human studies pose a challenging problem to be addressed in order to have robust clinical evidence to support SCS as a viable PD treatment.

Common Myths and Misconceptions That Sidetrack Parkinson Disease Treatment, to the Detriment of Patients

Parkinson disease symptoms become apparent when there has been substantial loss of brain dopamine. That is the consequence of the slow progression of the Lewy body neurodegenerative process. Replenishment of brain dopamine with levodopa therapy dates back approximately a half century and continues to be the most efficacious symptomatic treatment. Understanding the fundamentals of levodopa treatment is crucial to therapeutic success. Various myths over the years have sabotaged treatment outcomes and have discouraged primary care physicians from managing patients with Parkinson disease. That is unfortunate because in some regions, neurologists, and in particular movement specialists, are in short supply. The long history of these persistent levodopa myths and the counterarguments are the focus of this article.

Combined in Vitro-in Silico Approach to Predict Deposition and Pharmacokinetics of Budesonide Dry Powder Inhalers

PURPOSE

A combined in vitro - in silico methodology was designed to estimate pharmacokinetics of budesonide delivered via dry powder inhaler.

METHODS

Particle size distributions from three budesonide DPIs, measured with a Next Generation Impactor and Alberta Idealized Throat, were input into a lung deposition model to predict regional deposition. Subsequent systemic exposure was estimated using a pharmacokinetic model that incorporated Nernst-Brunner dissolution in the conducting airways to predict the net influence of dissolution, mucociliary clearance, and absorption.

RESULTS

DPIs demonstrated significant in vitro differences in deposition, resulting in large differences in simulated regional deposition in the central conducting airways and the alveolar region. Similar but low deposition in the small conducting airways was observed with each DPI. Pharmacokinetic predictions showed good agreement with in vivo data from the literature. Peak systemic concentration was tied primarily to the alveolar dose, while the area under the curve was more dependent on the total lung dose. Tracheobronchial deposition was poorly correlated with pharmacokinetic data.

CONCLUSIONS

Combination of realistic in vitro experiments, lung deposition modeling, and pharmacokinetic modeling was shown to provide reasonable estimation of in vivo systemic exposure from DPIs. Such combined approaches are useful in the development of orally inhaled drug products.

Challenges and Perspectives in the Management of Late-Stage Parkinson's Disease

Parkinson’s disease (PD) is a common neurodegenerative disorder, with a continuously increasing prevalence. With improved clinical and therapeutic management of PD, more patients reach later stages of the disease, meaning they may face new clinical problems that were not commonly approached. This gave way to the description of a new PD stage, late-stage PD (LSPD), which is clinically discernible from the advanced-stage one. Therefore, LSPD patients have new and different needs, regarding pharmacological and non pharmacological interventions, including palliative care and multidisciplinary teams. LSPD patients constitute an‘orphan population’, who traditionally was excluded from previous studies, due to its high disability. With this manuscript, we intend to review specific management challenges of LSPD patients, covering this new concept and its clinical features, how to assess these patients, therapeutic recommendations, as well as discussing ongoing research and future perspectives.

Nuclear Factor-κB Dysregulation and α-Synuclein Pathology: Critical Interplay in the Pathogenesis of Parkinson's Disease

The loss of dopaminergic neurons of the nigrostriatal system underlies the onset of the typical motor symptoms of Parkinson's disease (PD). Lewy bodies (LB) and Lewy neurites (LN), proteinaceous inclusions mainly composed of insoluble α-synuclein (α-syn) fibrils are key neuropathological hallmarks of the brain of affected patients. Compelling evidence supports that in the early prodromal phases of PD, synaptic terminal and axonal alterations initiate and drive a retrograde degeneration process culminating with the loss of nigral dopaminergic neurons. This notwithstanding, the molecular triggers remain to be fully elucidated. Although it has been shown that α-syn fibrillary aggregation can induce early synaptic and axonal impairment and cause nigrostriatal degeneration, we still ignore how and why α-syn fibrillation begins. Nuclear factor-κB (NF-κB) transcription factors, key regulators of inflammation and apoptosis, are involved in the brain programming of systemic aging as well as in the pathogenesis of several neurodegenerative diseases. The NF-κB family of factors consists of five different subunits (c-Rel, p65/RelA, p50, RelB, and p52), which combine to form transcriptionally active dimers. Different findings point out a role of RelA in PD. Interestingly, the nuclear content of RelA is abnormally increased in nigral dopamine (DA) neurons and glial cells of PD patients. Inhibition of RelA exert neuroprotection against (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) MPTP and 1-methyl-4-phenylpyridinium (MPP+) toxicity, suggesting that this factor decreases neuronal resilience. Conversely, the c-Rel subunit can exert neuroprotective actions. We recently described that mice deficient for c-Rel develop a PD-like motor and non-motor phenotype characterized by progressive brain α-syn accumulation and early synaptic changes preceding the frank loss of nigrostriatal neurons. This evidence supports that dysregulations in this transcription factors may be involved in the onset of PD. This review highlights observations supporting a possible interplay between NF-κB dysregulation and α-syn pathology in PD, with the aim to disclose novel potential mechanisms involved in the pathogenesis of this disorder.

Inhaled levodopa for intermittent treatment of OFF episodes in patients with Parkinson's disease

Introduction: Many patients with advanced Parkinson's disease (PD) have inadequate control of motor symptoms despite optimized treatment. Predictable and unpredictable OFF periods severely interfere with the quality of life. A drug that easily and rapidly reverts the OFF state is still needed. Subcutaneous apomorphine, the only approved drug for this indication, although efficacious, is not widely used probably due to its potential side effects and complicated administration.Levodopa is the most efficacious drug for the treatment of PD motor symptoms. However, issues related to the oral route and intestinal absorption in later disease stages render this route lengthy and inefficacious.Areas covered: Literature on the development of an inhaled formulation of levodopa has been reviewed. Significant advances in the field of pulmonary delivery systems and in dry powders have enabled the development of a new formulation of levodopa that can be inhaled and adequate blood levels rapidly achieved, bypassing intestinal absorption. Several clinical trials have reported efficacy, safety, and tolerability data. Some pulmonary-related adverse events have been reported but are mostly mild.Expert opinion: This new way of administering levodopa is likely to be very welcome and may fill a gap for OFF rescue treatments, at least for some patients.

Patterns and Determinants of Prescribing for Parkinson's Disease: A Systematic Literature Review

Since the discovery of levodopa (L-dopa) in 1967, the range of medications available to treat Parkinson's disease has increased significantly and guidance on the use, efficacy, and safety of these medications has evolved. To assess levels of adherence to national prescribing guidelines and awareness of changes in the efficacy and safety data published in the profiles of medications for the treatment of PD, we have reviewed studies on patterns and determinants of prescribing PD medications conducted in the last 50 years (since the discovery of L-dopa). A systematic literature review was conducted using EMBASE (1967 to March, 2018), Ovid MEDLINE(R) ALL (1967 to March 16, 2018), PsycINFO (1967 to the 2nd week of March, 2018), and PubMed to identify all studies measuring prescribing patterns of PD medication between 1967 and 2017. Study design, source of data, country, year of study, number of patients and/or prescriptions, unit of analysis, prescribing determinants, and percentage utilisation of PD medications were extracted where possible. 44 studies examining prescribing patterns and/or prescribing determinants across 17 countries were identified. Unsurprisingly, L-dopa was the most commonly prescribed medication in all studies, accounting for 46.50% to 100% of all prescriptions for PD. In several studies, the prescribing rate of ergot-derived dopamine agonists (DAs) decreased over time in concordance with guidance. In contrast, the prescribing rates of non-ergot DAs increased over the last ten years in most of the included studies. In examining prescribing factors, two major categories were exemplified, patients' factors and prescribers' factors, with patients' age being the most common factor that affected the prescription in most studies. In conclusion, L-dopa is now the most commonly prescribed medication for cases of PD but there is large variation in the prescribing rates of catechol-O-methyltransferase (COMT) inhibitors, monoamine oxidase B (MAO-B) inhibitors, amantadine, and anticholinergics between countries. New studies examining the effects of recent clinical trials and measuring the prescribing rates of newly approved medications are warranted.

Comparison Between Levodopa-Carbidopa Intestinal Gel Infusion and Subthalamic Nucleus Deep-Brain Stimulation for Advanced Parkinson's Disease: A Systematic Review and Meta-Analysis

Background: Currently, some advanced treatments such as Levodopa-Carbidopa intestinal gel infusion (LCIG), deep-brain stimulation (DBS), and subcutaneous apomorphine infusion have become alternative strategies for advanced Parkinson's disease (PD). However, which treatment is better for individual patients remains unclear. This review aims to compare therapeutic effects of motor and/or non-motor symptoms of advanced PD patients between LCIG and DBS.

Methods: We manually searched electronic databases (PubMed, Embase, Cochrane Library) and reference lists of included articles published until April 04, 2019 using related terms, without language restriction. We included case-controlled cohort studies and randomized-controlled trials, which directly compared differences between LCIG and DBS. The Newcastle-Ottawa scale (NOS), proposed by the Cochrane Collaboration, was utilized to assess the quality of the included studies. Two investigators independently extracted data from each trial. Pooled standard-mean differences (SMDs) and relative risks (RRs) with 95% confidence intervals (CIs) were calculated by meta-analysis. Outcomes were grouped according to the part III and part IV of the Unified Parkinson Disease Rating Scale (UPDRS) and adverse events. We also descriptively reviewed some data, which were unavailable for statistical analysis.

Results: This review included five cohort trials of 257 patients for meta-analysis. There were no significant differences between LCIG and subthalamic nucleus deep-brain stimulation (STN-DBS) on UPDRS-III and adverse events comparisons: UPDRS-III (pooled SMDs = 0.200, 95% CI: −0.126–0.527, P = 0.230), total adverse events (pooled RRs = 1.279, 95% CI: 0.983–1.664, P = 0.067), serious adverse events (pooled RRs = 1.539, 95% CI: 0.664–3.566, P = 0.315). Notably, the improvement of UPDRS-IV was more significant in STN-DBS groups: pooled SMDs = 0.857, 95% CI: 0.130–1.584, P = 0.021. However, the heterogeneity was moderate for UPDRS-IV (I² = 73.8%).

Conclusion: LCIG has comparable effects to STN-DBS on motor function for advanced PD, with acceptable tolerability. More large, well-designed trials are needed to assess the comparability of LCIG and STN-DBS in the future.

Evaluation of Selected Natural Compounds as Dual Inhibitors of Catechol-O-Methyltransferase and Monoamine Oxidase

Background:

The most effective symptomatic treatment of Parkinson’s disease remains the metabolic precursor of dopamine, L-dopa. To enhance the efficacy of L-dopa, it is often combined with inhibitors of the enzymes, catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO) B, key metabolic enzymes of L-dopa and dopamine.

Objective:

This study attempted to discover compounds that exhibit dual inhibition of COMT and MAO-B among a library of 40 structurally diverse natural compounds. Such dual acting inhibitors may be effective as adjuncts to L-dopa and offer enhanced value in the management of Parkinson’s disease.

Methods:

Selected natural compounds were evaluated as in vitro inhibitors of rat liver COMT and recombinant human MAO. Reversibility of MAO inhibition was investigated by dialysis.

Results:

Among the natural compounds morin (IC50 = 1.32 µM), chlorogenic acid (IC50 = 6.17 µM), (+)-catechin (IC50 = 0.86 µM), alizarin (IC50 = 0.88 µM), fisetin (IC50 = 5.78 µM) and rutin (IC50 = 25.3 µM) exhibited COMT inhibition. Among these active COMT inhibitors only morin (IC50 = 16.2 µM), alizarin (IC50 = 8.16 µM) and fisetin (IC50 = 7.33 µM) were noteworthy MAO inhibitors, with specificity for MAO-A.

Conclusion:

None of the natural products investigated here are dual COMT/MAO-B inhibitors. However, good potency COMT inhibitors have been identified, which may serve as leads for future development of COMT inhibitors.