Different Catechol-O-Methyl Transferase Inhibitors in Parkinson's Disease: A Bayesian Network Meta-Analysis

Selenium Nanoparticles as Neuroprotective Agents: Insights into Molecular Mechanisms for Parkinson's Disease Treatment

Oxidative stress and the accumulation of misfolded proteins in the brain are the main causes of Parkinson's disease (PD). Several nanoparticles have been used as therapeutics for PD. Despite their therapeutic potential, these nanoparticles induce multiple stresses upon entry. Selenium (Se), an essential nutrient in the human body, helps in DNA formation, stress control, and cell protection from damage and infections. It can also regulate thyroid hormone metabolism, reduce brain damage, boost immunity, and promote reproductive health. Selenium nanoparticles (Se-NPs), a bioactive substance, have been employed as treatments in several disciplines, particularly as antioxidants. Se-NP, whether functionalized or not, can protect mitochondria by enhancing levels of reactive oxygen species (ROS) scavenging enzymes in the brain. They can also promote dopamine synthesis. By inhibiting the aggregation of tau, α-synuclein, and/or Aβ, they can reduce the cellular toxicities. The ability of the blood-brain barrier to absorb Se-NPs which maintain a healthy microenvironment is essential for brain homeostasis. This review focuses on stress-induced neurodegeneration and its critical control using Se-NP. Due to its ability to inhibit cellular stress and the pathophysiologies of PD, Se-NP is a promising neuroprotector with its anti-inflammatory, non-toxic, and antimicrobial properties.

Effectiveness and safety of different catechol-o-methyl transferase inhibitors for patients with parkinson's disease: Systematic review and network meta-analysis

BACKGROUND

Levodopa treatment requires the addition of other drugs, such as catechol-O-methyl transferase (COMT) inhibitors, to alleviate motor fluctuations in advanced parkinson's disease (PD). However, the optimal strategy, including the type and dose of COMT inhibitors remains unknown. This systematic review and network meta-analysis aimed to assess the efficacy and safety of different COMT inhibitors and for treating PD patients.

METHODS

PubMed, Embase, Cochrane Library and Web of Science were screened up to November 20, 2022. Randomized controlled trials (RCTs) of COMT inhibitors (entacapone, opicapone, tolcapone) for PD patients were included. Eligible outcomes were total ON-time, rate of ON-time >1 h, total daily dose of levodopa therapy, mean change from baseline to final follow up in Unified Parkinson's Disease Rating Scale (UPDRS) part III scores, adverse events and dyskinesia. Network meta-analyses integrated direct and indirect evidence with placebo as a common comparator.

RESULTS

We identified 18 studies with 7564 patients. Opicapone, entacapone, and tolcapone could increase total ON-time when compared with placebo. However, opicapone (25 mg, MD 4.0, 95%CrI: 1.1-7.5) and opicapone (50 mg, MD 5.1, 95%CrI: 2.2-8.7) statistically significant increase the total ON-time. opicapone and entacapone could increase the rate of ON-time >1 h when compared with placebo. Only opicapone (5 mg) showed no statistically significant with placebo (OR 1.4, 95%CrI: 0.74-2.4). We found that opicapone (50 mg, SURCA, 0.796) is the best option compared with other treatments. TOL (200 mg) was ranked highest in the rank probability test for total daily dose of levodopa therapy, followed by OPI (50 mg), TOL (400 mg) and TOL (100 mg) in order. SUCRA rankings identified TOL (200 mg) as the most likely therapy for increasing adverse events (SUCRA 27.19%), followed by TOL (400 mg, SUCRA 27.20%) and OPI (5 mg, SUCRA 30.81%). The SUCRA probabilities were 91.6%, 75.2%, 67.9%, 59.3%, 45.6%, 41.1%, 35.1%, 24.6% and 9.4% for PLA, TOL (400 mg), ENT (100 mg), ENT (200 mg), OPI (5 mg), TOL (100 mg), OPI (25 mg), OPI (50 mg), and TOL (200 mg) respectively.

CONCLUSION

In conclusion, opicapone (50 mg) may be a better choice for treatment PD when compared with other COMT inhibitors.

Comparative efficacy and safety of adjunctive drugs to levodopa for fluctuating Parkinson's disease - network meta-analysis

It remains unclear which adjunctive drug for Parkinson's disease (PD) in combination with levodopa is more effective, tolerable, and safe. We aimed to compare the efficacy, tolerability, and safety among anti-PD drugs from several classes in patients with fluctuating PD who received levodopa through network meta-analysis (NMA). Twelve anti-PD drugs belonging to 4 different drug classes (dopamine agonists, monoamine oxidase type B inhibitors, catechol-O-methyl transferase inhibitors, and an adenosine A2A receptor antagonist) were selected. We systematically searched PubMed, Embase, and the Cochrane Library for eligible randomized controlled trials (RCTs) comparing placebo with anti-PD drug or among anti-PD drugs in patients with PD who experienced motor fluctuations or wearing-off and received levodopa. We included 54 RCTs in the analysis. The NMA was performed under a frequentist framework using a random-effects model. The efficacy outcome was change in daily off-time, and the tolerability outcome was discontinuation due to all causes. Safety outcomes included discontinuation due to adverse events (AEs) and the incidence of AEs, dyskinesia, hallucination, and orthostatic hypotension. According to the surface under the cumulative ranking curve (SUCRA) in the NMA, ropinirole transdermal patch (SUCRA, 0.861) ranked the highest in efficacy, followed by pramipexole (0.762), ropinirole extended release (ER) (0.750), and safinamide (0.691). In terms of tolerability, ropinirole (0.954) ranked the highest, followed by pramipexole (0.857), safinamide (0.717), and ropinirole ER (0.708). Each anti-PD drug had different SUCRA ranking profiles for the safety outcomes. These findings suggest that ropinirole, pramipexole, and safinamide are well-balanced anti-PD drugs that satisfy both efficacy and tolerability outcomes.

Treatment Patterns and Healthcare Resource Use in Medicare Beneficiaries with Parkinson's Disease

Background

Studies on real-world treatment patterns and long-term economic burden of Parkinson's disease (PD) have been limited.

Objective

To assess treatment patterns, healthcare resource utilization (HRU), and costs associated with PD symptoms and treatment-related adverse events (AEs) among Medicare beneficiaries in the United States.

Methods

A 100% Medicare Fee-For-Service data (2006-2020) of patients with PD were analyzed. PD treatment patterns were described for the subset of patients who had no previously observed PD treatments or diagnoses (ie, the incident cohort). HRU and healthcare costs associated with PD symptoms were assessed for all patients with PD (ie, the overall cohort) and that associated with treatment-related AEs were assessed for the subset of patients who received PD treatments after PD diagnosis (ie, the active treatment cohort), using longitudinal models with repeated measures.

Results

Overall, 318,582 patients were included (mean age at PD diagnosis: 77.4 years; 53.3% female). Among patients in the incident cohort (N=214,829), 51.1% initiated levodopa monotherapy and 5.9% initiated dopamine agonists (DAs) monotherapy as first-line treatment. The proportion of incident patients treated with DAs and other PD therapies generally increased from post-diagnosis years 1 to 10. The median time from diagnosis to PD treatment initiation was 2.0 months; the median time to treatment discontinuation was the longest with levodopa (18.7 months), followed by DAs (9.5 months). In the overall cohort, PD symptoms, especially motor symptoms and severe motor symptoms, were associated with significantly higher rates of HRU and costs. In the active treatment cohort (N=234,298), treatment-related AEs were associated with significantly higher rates of HRU and medical costs.

Conclusion

While levodopa is still the mainstay of PD management, considerable heterogeneity exists in real-world treatment patterns. Overall, PD symptoms and AEs were associated with significantly higher HRU and healthcare costs, suggesting unmet medical needs for PD treatments with better tolerability profiles.

Clinical benefit of MAO-B and COMT inhibition in Parkinson's disease: practical considerations

Inhibitors of monoamine oxidase B (MAO-B) and catechol-O-methyltransferase (COMT) are major strategies to reduce levodopa degradation and thus to increase and prolong its effect in striatal dopaminergic neurotransmission in Parkinson's disease patients. While selegiline/rasagiline and tolcapone/entacapone have been available on the market for more than one decade, safinamide and opicapone have been approved in 2015 and 2016, respectively. Meanwhile, comprehensive data from several post-authorization studies have described the use and specific characteristics of the individual substances in clinical practice under real-life conditions. Here, we summarize current knowledge on both medication classes, with a focus on the added clinical value in Parkinson's disease. Furthermore, we outline practical considerations in the treatment of motor fluctuations and provide an outlook on ongoing studies with MAO-B and COMT inhibitors.

Levodopa Dose Equivalency in Parkinson's Disease: Updated Systematic Review and Proposals

BACKGROUND

To compare drug regimens across clinical trials in Parkinson's disease (PD) conversion formulae between antiparkinsonian drugs have been developed. These are reported in relation to levodopa as the benchmark drug in PD pharmacotherapy as 'levodopa equivalent dose' (LED). Currently, the LED conversion formulae proposed in 2010 by Tomlinson et al. based on a systematic review are predominantly used. However, new drugs with established and novel mechanisms of action and novel formulations of longstanding drugs have been developed since 2010. Therefore, consensus proposals for updated LED conversion formulae are needed.

OBJECTIVES

To update LED conversion formulae based on a systematic review.

METHODS

The MEDLINE, CENTRAL, and Embase databases were searched from January 2010 to July 2021. Additionally, in a standardized process according to the GRADE grid method, consensus proposals were issued for drugs with scarce data on levodopa dose equivalency.

RESULTS

The systematic database search yielded 3076 articles of which 682 were eligible for inclusion in the systematic review. Based on these data and the standardized consensus process, we present proposals for LED conversion formulae for a wide range of drugs that are currently available for the pharmacotherapy of PD or are expected to be introduced soon.

CONCLUSIONS

The LED conversion formulae issued in this Position Paper will serve as a research tool to compare the equivalence of antiparkinsonian medication across PD study cohorts and facilitate research on the clinical efficacy of pharmacological and surgical treatments as well as other non-pharmacological interventions in PD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Levodopa-carbidopa intestinal gel in advanced Parkinson's disease: long-term results from COSMOS

BACKGROUND

While immediate benefits of levodopa-carbidopa intestinal gel (LCIG) are evident in patients with Parkinson's disease (PD), long-term LCIG effects require further study.

OBJECTIVES

We explored long-term LCIG on motor symptoms, nonmotor symptoms (NMS), and LCIG treatment settings in patients with advanced PD (APD).

METHODS

Data were obtained (medical records and patient visit) from COSMOS, a multinational, retrospective, cross-sectional post-marketing observational study in patients with APD. Patients were stratified into 5 groups based on LCIG treatment duration at the patient visit, from 1-2 to > 5 years LCIG. Between-group differences were assessed for changes from baseline in LCIG settings, motor symptoms, NMS, add-on medications, and safety.

RESULTS

Out of 387 patients, the number of patients per LCIG group was: > 1- ≤ 2 years LCIG (n = 156); > 2- ≤ 3 years LCIG (n = 80); > 3- ≤ 4 years LCIG (n = 61); > 4- ≤ 5 years LCIG (n = 30); > 5 years LCIG (n = 60). Baseline values were similar; data reported are changes from the baseline. There were reductions in "off" time, dyskinesia duration, and severity across LCIG groups. Prevalence, severity, and frequency of many individual motor symptoms and some NMS were reduced amongst all LCIG groups, with few differences between groups. Doses for LCIG, LEDD and LEDD for add-on medications were similar across groups both at LCIG initiation and patient visit. Adverse events were similar across all LCIG groups and consistent with the established safety profile of LCIG.

CONCLUSIONS

LCIG may provide sustained, long-term symptom control, while potentially avoiding increases in add-on medication dosages.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03362879. Number and date: P16-831, November 30, 2017.

Two Faces of Catechol-O-Methyltransferase Inhibitor on One-Carbon Metabolism in Parkinson's Disease: A Meta-Analysis

Levodopa (L-dopa) and catechol-O-methyltransferase (COMT) inhibition are widely used therapeutics in Parkinson's disease (PD). Despite their therapeutic effects, it was raised that nutrients involved in one-carbon metabolism can be deteriorated by PD therapies. The aim of this meta-analysis was to investigate the impact of L-dopa and COMT inhibitors on levels of homocysteine (Hcy), vitamin B₁₂ and folate in patients with PD. A total of 35 case-control studies from 14 different countries were selected through PubMed, MEDLINE and Google Scholar and were meta-analyzed. In the L-dopa group, the Hcy level was higher compared to the PD without L-dopa group (SMD: 5.11 μmol/L, 95% CI: 3.56 to 6.66). Moreover, vitamin B₁₂ and folate levels in the L-dopa group were lower compared to the healthy control (SMD: -62.67 pg/mL, 95% CI: -86.53 to -38.81; SMD: -0.89 ng/mL, 95% CI: -1.44 to -0.33, respectively). The COMT inhibitor group showed lower levels of Hcy (SMD: -3.78 μmol/L, 95% CI: -5.27 to -2.29) and vitamin B₁₂ (SMD: -51.01 pg/mL, 95% CI: -91.45 to -10.57), but higher folate levels (SMD: 1.78 ng/mL, 95% CI: -0.59 to 4.15) compared to the L-dopa group. COMT inhibitors may ameliorate L-dopa-induced hyper-homocysteine and folate deficiency but exacerbate vitamin B₁₂ deficiency.

Effective Management of "OFF" Episodes in Parkinson's Disease: Emerging Treatment Strategies and Unmet Clinical Needs

Motor complications related to the chronic administration of levodopa and failure to prevent the neurodegenerative disease process counterbalance the pivotal discovery of levodopa as the cornerstone of PD treatment. Excellent motor control is offered early during the course of treatment, but this diminishes as pathological changes in the striatum lead to synaptic dopamine levels becoming completely dependent on exogenous dopamine. This non-physiologic stimulation of dopamine receptors eventually manifests as OFF episodes. As no disease modifying therapy exists for PD that can disrupt these pathological changes, most research and treatment focuses on optimization of dopaminergic stimulation of striatal receptors so that they mimic tonic, physiologic stimulation as closely as possible. Strategies focusing on these challenges have included non-pharmacologic approaches, optimizing levodopa pharmacokinetics, using adjunctive treatments including those with non-dopaminergic mechanisms, and implementing rescue therapies. Device aided therapies, including surgery, are also available. In this review, we will focus on effective management of motor symptoms related to OFF periods, including emerging strategies. Unmet clinical needs will be discussed, including non-motor symptoms, targeted molecular therapies and disease modifying therapy.

Glycolysis: The Next Big Breakthrough in Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disease characterized by the death of dopaminergic neurons. Its pathogenesis comprises defects in the physiological pathway of mitophagy and mutations in the genes involved in this process's regulatory mechanism. PD manifests itself with multiple motor and non-motor symptoms, and currently, there are multiple pharmacological treatments, and unconventional non-drug treatments available. The mainstay of Parkinson's disease treatment has centered around directly manipulating neural mechanisms to retain high dopamine levels, either by exogenous administration, increasing intrinsic production, or inhibiting the breakdown of dopamine. In this review, we highlight a new potential biochemical modality of treatment, treating PD through glycolysis. We highlight how terazosin (TZ), via PGK1, increases ATP levels and how enhanced glycolysis serves a neuroprotective role in PD, and compensates for damage caused by mitophagy. We also discuss the role of quercetin, a bioactive flavonoid, in preventing the development of PD, and reversing mitochondrial dysfunction but only so in diabetic patients. Thus, further research should be conducted on glycolysis as a protective target in PD that can serve to not just prevent, but also alleviate the non-dopaminergic signs and symptoms of PD.

Chalcone Derivatives with a High Potential as Multifunctional Antioxidant Neuroprotectors

A systematic, rational search for chalcone derivatives with multifunctional behavior has been carried out, with the support of a computer-assisted protocol (CADMA-Chem). A total of 568 derivatives were constructed by incorporating functional groups into the chalcone structure. Selection scores were calculated from ADME properties, toxicity, and manufacturability descriptors. They were used to select a subset of molecules (23) with the best drug-like behavior. Reactivity indices were calculated for this subset. They were chosen to account for electron and hydrogen atom donating capabilities, which are key processes for antioxidant activity. The indexes showed that four chalcone derivatives (dCHA-279, dCHA-568, dCHA-553, and dCHA-283) are better electron and H donors than the parent molecule and some reference antioxidants (Trolox, ascorbic acid, and α-tocopherol). In addition, based on molecular docking, they are predicted to act as catechol-O-methyltransferase (COMT), acetylcholinesterase (AChE), and monoamine oxidase B (MAO-B) inhibitors. Therefore, these four molecules are proposed as promising candidates to act as multifunctional antioxidants with neuroprotective effects.

Evaluating Opicapone as Add-on Treatment to Levodopa/DDCI in Patients with Parkinson's Disease

COMT (catechol-O-methyltransferase) inhibitors are key therapeutic agents in the management of motor fluctuations (MF) in patients with Parkinson's disease (PD). As levodopa/DDCI add-on therapy, their main benefit lies in increasing ON-time and reducing OFF-time for PD patients in the middle stages of the disease. Two of the three available COMT inhibitors, tolcapone and entacapone, have been approved for over two decades. Opicapone, a third-generation COMT inhibitor approved in 2016, was designed with the aim of overcoming specific challenges of the earlier generation compounds, specifically hepatotoxicity and short effect duration. This review aims at highlighting the specific properties and characteristics of opicapone, namely combining efficacy with good tolerability as demonstrated in the registration studies and since then confirmed under real-world conditions. Opicapone has been shown to be effective in patients with early, as well as late motor fluctuations. Whilst patients in the earlier Hoehn and Yahr stages benefit more than patients in later stages, the incidence of dyskinesia in patients with recent onset MF is around half that of patients with more established fluctuations. With the added advantage of a once-daily administration, this particular COMT inhibitor provides a simple, yet effective therapy for patients with Parkinson's disease and MF.

Opicapone as an add-on to levodopa for reducing end-of-dose motor fluctuations in Parkinson's disease: a systematic review and meta-analysis

Aim: To assess the clinical efficacy and safety profile of opicapone (25 and 50 mg once daily) versus placebo. Patients: Levodopa-treated adults with Parkinson's disease. Material & methods: A systematic review and meta-analysis were conducted. Results: Opicapone provided a greater reduction in the absolute OFF-time, increased the chances of ≥1-h reduction in the OFF-time and ≥1-h increase in the ON-time compared with placebo. Receiving opicapone more often facilitated levodopa dose reduction versus placebo. There were no differences in the occurrence of adverse events (severe and leading to drug discontinuation), but receiving opicapone increased the frequency of dyskinesia. Conclusion: Opicapone demonstrated superior clinical efficacy to placebo, with a comparable general safety profile.

The recent guidelines for pharmacotherapy of Parkinson’s Disease

Parkinson’s Disease (PD) is one of the most frequent disorders of the central nervous system (CNS). PD is an age-related disease in that morbidity increases with age. The main symptoms of it are motor symptoms like bradykinesia, rigidity and resting tremor. These symptoms diminish the comfort of the patient’s life and may lead to immobility. Hence, rapid diagnosis and start of treatment are very important.

The pharmacotherapy of PD is difficult. PD involves an imbalance between the dopaminergic and cholinergic systems. Therefore, the mechanisms of action of currently available drugs are highly connected with the pathology of PD, and follow dopaminergic or anticholinergic control strategies. However, long-term use of many PD medications comes with serious side effects. Therefore, the search for new, more effective drugs involving different strategies to that current and having different targets is still on-going.

Identification of Potential Parkinson's Disease Drugs Based on Multi-Source Data Fusion and Convolutional Neural Network

Parkinson’s disease (PD) is a serious neurodegenerative disease. Most of the current treatment can only alleviate symptoms, but not stop the progress of the disease. Therefore, it is crucial to find medicines to completely cure PD. Finding new indications of existing drugs through drug repositioning can not only reduce risk and cost, but also improve research and development efficiently. A drug repurposing method was proposed to identify potential Parkinson’s disease-related drugs based on multi-source data integration and convolutional neural network. Multi-source data were used to construct similarity networks, and topology information were utilized to characterize drugs and PD-associated proteins. Then, diffusion component analysis method was employed to reduce the feature dimension. Finally, a convolutional neural network model was constructed to identify potential associations between existing drugs and LProts (PD-associated proteins). Based on 10-fold cross-validation, the developed method achieved an accuracy of 91.57%, specificity of 87.24%, sensitivity of 95.27%, Matthews correlation coefficient of 0.8304, area under the receiver operating characteristic curve of 0.9731 and area under the precision–recall curve of 0.9727, respectively. Compared with the state-of-the-art approaches, the current method demonstrates superiority in some aspects, such as sensitivity, accuracy, robustness, etc. In addition, some of the predicted potential PD therapeutics through molecular docking further proved that they can exert their efficacy by acting on the known targets of PD, and may be potential PD therapeutic drugs for further experimental research. It is anticipated that the current method may be considered as a powerful tool for drug repurposing and pathological mechanism studies.

Efficacy and Safety of Opicapone for Motor Fluctuations as an Adjuvant to Levodopa Therapy in Patients with Parkinson's Disease: A Systematic Review and Meta-Analysis

Background:

Long-term levodopa administration for treating Parkinson’s disease (PD) may shorten the duration of effect and cause dyskinesias, inducing the need for catechol-O-methyltransferase (COMT) inhibitors as adjuvant therapy.

Objective:

We provide pooled scientific evidence highlighting the efficacy and safety of opicapone, a newly approved COMT inhibitor, as an adjuvant to levodopa.

Methods:

We searched Ovid Medline, Embase, and Cochrane databases for relevant reports. Efficacy and safety were evaluated as off-time reduction and risk ratio (RR) of dyskinesia, respectively. Data were independently extracted using predefined criteria. Selected placebo-controlled trials were divided into double-blind and open-label periods. Using a random-effects model, the mean difference (MD) of the off-time reduction (efficacy), RR for the occurrence of dyskinesia, and on-time without/with troublesome dyskinesia (TD; safety assessment) were compared between opicapone and placebo groups.

Results:

Five studies from three randomized controlled trials were included, and a meta-analysis was performed with 407 patients receiving opicapone 50 mg and 402 patients receiving placebo. Compared with the placebo, opicapone (50 mg) reduced off-time by 49.91 min during the double-blind period (95% confidence intervals [CIs] = –71.39, –28.43; I² = 0%). The RR of dyskinesia was 3.43 times greater in the opicapone 50 mg group than in the placebo group (95% CI = 2.14, 5.51; I = 0%). Compared with the placebo, opicapone increased the on-time without TD by 44.62 min (95% CI = 22.60, 66.64; I² = 0%); the on-time increase with TD did not differ between treatments.

Conclusion:

Opicapone can play a positive role as an adjuvant to levodopa in patients with PD by reducing off-time and prolonging on-time without PD.

[Relevance of COMT inhibitors in the treatment of motor fluctuations]

Catechol O‑methyltransferase (COMT) inhibitors have been established in the treatment of Parkinson's disease for more than 20 years. They are considered the medication of choice for treating motor fluctuations. The available COMT inhibitors, entacapone, opicapone and tolcapone, differ pharmacokinetically in terms of their half-lives with implications for the dose frequency, in their indication requirements and in their spectrum of side effects, including diarrhea and yellow discoloration of urine. Many patients with motor fluctuations are currently not treated with COMT inhibitors and are, therefore, unlikely to receive individually optimized drug treatment. This manuscript summarizes the results of a working group including several Parkinson's disease experts, in which the value of COMT inhibitors was critically discussed.