Opicapone to Treat Early Wearing-off in Parkinson's Disease Patients: The Korean ADOPTION Trial

BACKGROUND

Increasing levodopa (L-dopa)/dopa decarboxylase inhibitor (DDCI) daily dose or adding a catechol-O-methyltransferase (COMT) inhibitor to levodopa/DDCI therapy are strategies used to manage wearing-off symptoms in Parkinson's disease (PD) patients.

OBJECTIVES

To evaluate the COMT inhibitor opicapone versus an additional dose of levodopa to treat early wearing-off in PD patients.

METHODS

ADOPTION was a randomized, parallel-group, open-label, Phase 4 study conducted in Korea. At baseline, eligible patients were randomized (1:1) to opicapone 50 mg (n = 87) or L-dopa 100 mg (n = 81) (added to current L-dopa/DDCI therapy) for 4 weeks. The main efficacy endpoint was change from baseline to end of study in absolute off time. Other endpoints included changes in on time, in Movement Disorder Society-Unified Parkinson's Disease Rating Scale and 8-item PD Questionnaire scores, and the Clinical and Patient Global Impression of Improvement/Change.

RESULTS

The adjusted mean in absolute off time was significantly greater for opicapone 50 mg than for L-dopa 100 mg (-62.1 vs. -16.7 minutes; P = 0.0015). Opicapone-treated patients also reported a greater reduction in the percentage of off time (P = 0.0015), a greater increase in absolute on time (P = 0.0338) and a greater increase in the percentage of on time (P = 0.0015). There were no significant differences in other secondary endpoints. The L-dopa equivalent daily dose was significantly higher in the opicapone group (750.9 vs. 690.0 mg; P = 0.0247), when a 0.5 conversion factor is applied.

CONCLUSIONS

Opicapone 50 mg was more effective than an additional 100 mg L-dopa dose at decreasing off time in patients with PD and early wearing-off.

Opicapone versus entacapone: Head-to-head retrospective data-based comparison of healthcare resource utilization in people with Parkinson's disease new to catechol-O-methyltransferase (COMT) inhibitor treatment

BACKGROUND AND PURPOSE

Motor fluctuations are a significant driver of healthcare resource utilization (HCRU) in people with Parkinson's disease (pwPD). A common management strategy is to include catechol-O-methyltransferase (COMT) inhibition with either opicapone or entacapone in the levodopa regimen. However, to date, there has been a lack of head-to-head data comparing the two COMT inhibitors in real-world settings. The aim of this study was to evaluate changes in HCRU and effect on sleep medications when opicapone was initiated as first COMT inhibitor versus entacapone.

METHODS

In this retrospective cohort study, we assessed HCRU outcomes in pwPD naïve to COMT inhibition via UK electronic healthcare records (Clinical Practice Research Datalink and Hospital Episodes Statistics databases, June 2016 to December 2019). HCRU outcomes were assessed before (baseline) and after COMT inhibitor prescription at 0-6 months, 7-12 months and 13-18 months. Opicapone-treated pwPD were algorithm-matched (1:4) to entacapone-treated pwPD.

RESULTS

By 6 months, treatment with opicapone resulted in 18.5% fewer neurology outpatient visits compared to entacapone treatment; this effect was maintained until the last follow-up (18 months). In the opicapone group, the mean levodopa equivalent daily dose decreased over the first year and then stabilized, whereas the entacapone-treated group showed an initial decrease in the first 6 months followed by a dose increase between 7 and 18 months. Neither COMT inhibitor had a significant impact on sleep medication use.

CONCLUSIONS

This head-to-head study is the first to demonstrate, using 'real-world' data, that initiating COMT inhibition with opicapone is likely to decrease the need for post-treatment HCRU versus initiation of COMT inhibition with entacapone.

Opicapone Pharmacokinetics and Effects on Catechol- O -Methyltransferase Activity and Levodopa Pharmacokinetics in Patients With Parkinson Disease Receiving Carbidopa/Levodopa

OBJECTIVES

Levodopa (LD) administered with dopa decarboxylase inhibitor is predominantly metabolized in the periphery by catechol- O -methyltransferase (COMT) to 3- O -methyldopa (3-OMD). Catechol- O -methyltransferase inhibition can improve treatment outcomes by decreasing variability in circulating LD concentrations. Opicapone is a once-daily COMT inhibitor approved in the US adjunctive to carbidopa (CD)/LD in patients with Parkinson disease experiencing "OFF" episodes. This study aimed to evaluate the pharmacokinetics and pharmacodynamics of once-daily opicapone 50 mg adjunctive to CD/LD in patients with stable Parkinson disease.

METHODS

Once-daily opicapone 50 mg was administered the evenings of days 1 to 14. Participants were randomized to receive CD/LD (25/100 mg) every 3 or 4 hours (Q3H or Q4H). Participants received Q3H or Q4H CD/LD on days 1, 2, and 15 and their usual CD/LD regimen on other days. Serial blood samples were collected to determine plasma opicapone, LD, and 3-OMD concentrations and erythrocyte soluble COMT (S-COMT) activity. The effects of opicapone on S-COMT, LD, and 3-OMD were assessed. Mean (SD) values are presented.

RESULTS

Sixteen participants were enrolled. At steady-state (day 14), opicapone Cmax (peak plasma concentration) and AUC 0-last (area under the curve-time curve) were 459 ± 252 ng/mL and 2022 ± 783 ng/mL·h, respectively. Maximum COMT inhibition was 83.4 ± 4.9% of baseline on day 14. After opicapone administration, LD total AUC, peak concentration, and trough concentration increased; peak-to-trough fluctuation index decreased. Correspondingly, 3-OMD total AUC, peak concentration, and trough concentration decreased.

CONCLUSIONS

Adding once-daily opicapone 50 mg to LD resulted in marked and extended COMT inhibition, which increased systemic exposure to LD. These changes translated into higher trough concentrations and decreased peak-to-trough fluctuations for LD.

Adverse event profiles of adjuvant treatment with opicapone in Parkinson's disease: A systematic review and meta-analysis

Background: Opicapone, a novel third-generation catechol-O-methyltransferase inhibitor, has demonstrated efficacy in Parkinson's Disease (PD) patients with end-of-dose motor fluctuations. Objective: This study aimed to compare the short-term (<6 months) and long-term (≥6 months) tolerability of opicapone adjuvant treatment in PD patients. Method: Electronic databases including PubMed, Embase, Web of Science and Cochrane library were searched for randomized controlled trials (RCTs) and observational studies. The end points included any treatment-related adverse events (TEAEs), serious TEAEs (SAEs) and treatment discontinuation. A random-effects model was used to generate overall incidences of TEAE. Results: Three RCTs, three RCT extension studies and three open-label studies involving 2177 PD patients were evaluated. In the short-term studies, there were reports of TEAEs with an incidence of ≥5% in individuals treated with opicapone 50 mg, including dyskinesia (14.1%), elevated blood creatine phosphokinase levels (8.0%) and urinary tract infection (6.0%). Any TEAEs, SAEs and treatment discontinuation all occurred at rates of 62.9%, 4.8% and 9.3%, respectively. TEAEs with opicapone 50 mg that were reported by more than 5% of patients in long-term studies included dyskinesia (16.1%), dry mouth (12.1%), medication effect decreased (12.1%), PD exacerbated (7.8%), blood creatine phosphokinase level raised (7.4%), nausea (6.1%) and insomnia (5.1%). The incidence of any TEAEs, SAEs and treatment discontinuation were, correspondingly, 73.2%, 8.7% and 8.4%. Conclusion: These studies demonstrated that opicapone was generally well-tolerated and had a low risk of adverse events, suggesting that it could be a valuable therapeutic choice for people with PD.

Effect of Opicapone on Levodopa Pharmacokinetics in Patients with Fluctuating Parkinson's Disease

BACKGROUND

Inhibiting catechol-O-methyltransferase extends the plasma half-life of levodopa, potentially allowing physicians to optimize the levodopa regimen in patients with Parkinson's disease (PD) experiencing motor fluctuations.

OBJECTIVES

To evaluate the effects of once-daily opicapone on levodopa plasma pharmacokinetics and motor response when added to two different levodopa dosing regimens.

METHODS

A total of 24 patients with PD and motor fluctuations were enrolled in an exploratory, open-label, modified cross-over trial. Participants first received levodopa/carbidopa 500/125 mg (five intakes) for 2 weeks and were then randomly assigned (1:1) to levodopa/carbidopa 400/100 mg given over either four or five daily intakes plus opicapone 50 mg for an additional 2 weeks. Levodopa 12-hour pharmacokinetics was the primary outcome (ie, excluding the effect of last/evening levodopa/carbidopa intake), with motor complications evaluated as secondary outcomes.

RESULTS

Over 12-hour pharmacokinetics and compared with five-intake levodopa/carbidopa 500/125 mg without opicapone, maximal levodopa concentrations were similar or nonsignificantly higher on both levodopa/carbidopa 400/100 mg regimens plus opicapone. Despite a 100 mg lower total levodopa/carbidopa daily dose, adding opicapone 50 mg at least doubled the levodopa plasma half-life and minimal concentrations, with a significant ≈30% increase in total exposure. The levodopa fluctuation index was only significantly lower for the five intakes plus opicapone regimen (difference of -71.8%; P &lt; 0.0001). Modifications to levodopa pharmacokinetics were associated with decreased off time and increased on time.

CONCLUSIONS

Combining opicapone 50 mg with a 100 mg lower daily dose of levodopa provides higher levodopa bioavailability with avoidance of trough levels. Despite the lower levodopa dose, modifying the levodopa pharmacokinetic profile with opicapone was associated with decreased off time and increased on time. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

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.

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.

Opicapone in UK clinical practice: effectiveness, safety and cost analysis in patients with Parkinson's disease

Aim: This subanalysis of the OPTIPARK study aimed to confirm the effectiveness and safety of opicapone in patients with Parkinson's disease and motor fluctuations in clinical practice specifically in the UK and to assess the impact of opicapone on treatment costs. Methods: Patients received opicapone added to levodopa for 6 months. Clinical outcomes were assessed at 3 and 6 months and treatment costs at 6 months. Results: Most patients' general condition improved at 3 months, with sustained improvements reported at 6 months. Opicapone improved motor and non-motor symptoms at both timepoints, was generally well tolerated and reduced total treatment costs by GBP 3719. Conclusion: Opicapone added to levodopa resulted in clinical improvements and reduced treatment costs across UK clinical practice.

Opicapone Improves Global Non-Motor Symptoms Burden in Parkinson's Disease: An Open-Label Prospective Study

Patients with Parkinson’s disease (PD) can improve some non-motor symptoms (NMS) after starting treatment with opicapone. The aim of this study was to analyze the effectiveness of opicapone on global NMS burden in PD. OPEN-PD (Opicapone Effectiveness on Non-motor symptoms in Parkinson’s Disease) is a prospective open-label single-arm study conducted in 5 centers from Spain. The primary efficacy outcome was the change from baseline (V0) to the end of the observational period (6 months ± 30 days) (V2) in the Non-Motor Symptoms Scale (NMSS) total score. Different scales were used for analyzing the change in motor, NMS, quality of life (QoL), and disability. Thirty-three patients were included between JUL/2019 and JUN/2021 (age 63.3 ± 7.91; 60.6% males; 7.48 ± 4.22 years from symptoms onset). At 6 months, 30 patients completed the follow-up (90.9%). The NMSS total score was reduced by 27.3% (from 71.67 ± 37.12 at V0 to 52.1 ± 34.76 at V2; Cohen’s effect size = −0.97; p = 0.002). By domains, improvement was observed in sleep/fatigue (−40.1%; p < 0.0001), mood/apathy (−46.6%; p = 0.001), gastrointestinal symptoms (−20.7%; p = 0.029), and miscellaneous (−44.94%; p = 0.021). QoL also improved with a 18.4% reduction in the 39-item Parkinson’s Disease Quality of Life Questionnaire Summary Index (from 26.67 ± 17.61 at V0 to 21.75 ± 14.9 at V2; p = 0.001). A total of 13 adverse events in 11 patients (33.3%) were reported, 1 of which was severe (not related to opicapone). Dyskinesias and nausea were the most frequent (6.1%). Opicapone is well tolerated and improves global NMS burden and QoL in PD patients at 6 months.

Metabolism and disposition of opicapone in the rat and metabolic enzymes phenotyping

Opicapone (2,5‐dichloro‐3‐(5‐(3,4‐dihydroxy‐5‐nitrophenyl)‐1,2,4‐oxadiazol‐3‐yl)‐4,6‐dimethylpyridine 1‐oxide) is a selective catechol‐O‐methyltransferase inhibitor that has been granted marketing authorization in Europe, Japan, and United States. The present work describes the metabolism and disposition of opicapone in the rat obtained in support to its development and regulatory filling. Plasma levels and elimination of total radioactivity were determined after oral and intravenous administration of [¹⁴C]‐opicapone. The maximum plasma concentrations of opicapone‐related radioactivity were reached at early time points followed by a gradual return to baseline with a biphasic elimination. Fecal excretion was the primary route of elimination of total radioactivity. Quantitative distribution of drug‐related radioactivity demonstrated that opicapone and related metabolites did not distribute to the central nervous system. Opicapone was extensively metabolized in rats resulting in more than 20 phase I and phase II metabolites. Although O‐glucuronidation, ‐sulfation, and ‐methylation of the nitrocatechol moiety were the principal metabolic pathways, small amount of the N‐acetyl derivative was detected, as a result of reduction of the nitro group and subsequent conjugation. Other metabolic transformations included N‐oxide reduction to the pyridine derivative and reductive cleavage of 1,2,4‐oxadiazole ring followed by further conjugative reactions. Reaction phenotyping studies suggested that SULT 1A1*1 and *2 and UGT1A7, UGT1A8, UGT1A9, and UGT1A10 may be involved in opicapone sulfation and glucuronidation, respectively. However, the reductive metabolic pathways mediated by gut microflora cannot be excluded. Opicapone, in the rat, was found to be rapidly absorbed, widely distributed to peripheric tissues, metabolized mainly via conjugative pathways at the nitro catechol ring, and primarily excreted via feces.

The Added Benefit of Opicapone When Used Early in Parkinson's Disease Patients With Levodopa-Induced Motor Fluctuations: A Post-hoc Analysis of BIPARK-I and -II

Introduction: Opicapone (OPC) was efficacious in reducing OFF-time in two pivotal trials in patients with Parkinson's disease (PD) and end-of-dose motor fluctuations (BIPARK-I and -II). Post-hoc analyses of these trials evaluated the efficacy of OPC following pre-defined segmentation of the wide spectrum of motor fluctuations in PD.

Methods: Data from matching treatment arms in BIPARK-I and -II were combined for the placebo (PLC) and OPC 50-mg groups, and exploratory post-hoc analyses were performed to investigate the efficacy of OPC 50 mg vs. PLC in subgroups of patients who were in “earlier” vs. “later” stages of both their disease course (e.g., duration of PD <6 years vs. ≥6 years) and levodopa treatment pathway (e.g., number of daily levodopa intakes <4 vs. ≥4). Efficacy variables included changes from baseline in absolute OFF-time and total ON-time.

Results: The Full Analysis Set included 517 patients (PLC, n = 255; OPC 50 mg, n = 262). OPC 50 mg was significantly more effective than PLC in reducing OFF-time and increasing ON-time in the majority of subgroup analyses (p < 0.05). Moreover, patients in “earlier” stages of both their disease course and levodopa treatment pathway experienced numerically greater efficacy when using OPC 50 mg, in comparison with those in “later” stages.

Conclusion: OPC 50 mg was efficacious over the whole trajectory of motor fluctuation evolution in PD patients. There was also a signal for enhanced efficacy in patients who were earlier vs. later in their disease course and levodopa treatment pathway.

Redefining the strategy for the use of COMT inhibitors in Parkinson's disease: the role of opicapone

INTRODUCTION

Levodopa remains the gold-standard Parkinson's disease (PD) treatment, but the inevitable development of motor complications has led to intense activity in pursuit of its optimal delivery.

AREAS COVERED

Peripheral inhibition of dopa-decarboxylase has long been considered an essential component of levodopa treatment at every stage of illness. In contrast, only relatively recently have catechol-O-methyltransferase (COMT) inhibitors been utilized to block the other major pathway of degradation and optimize levodopa delivery to the brain. First and second-generation COMT inhibitors were deficient because of toxicity, sub-optimal pharmacokinetics or a short duration of effect. As such, they have only been employed once 'wearing-off' has developed. However, the third-generation COMT inhibitor, opicapone has overcome these difficulties and exhibits long-lasting enzyme inhibition without the toxicity observed with previous generations of COMT inhibitors. In clinical trials and real-world PD studies opicapone improves the levodopa plasma profile and results in a significant improvement in ON time in 'fluctuating' disease, but it has not yet been included in the algorithm for early treatment.

EXPERT OPINION

This review argues for a shift in the positioning of COMT inhibition with opicapone in the PD algorithm and lays out a pathway for proving its effectiveness in early disease.

Clinical Utility of Opicapone in the Management of Parkinson's Disease: A Short Review on Emerging Data and Place in Therapy

Parkinson’s disease (PD) is a prevalent neurodegenerative disorder, and levodopa (L-dopa) remains the most efficacious drug treatment for PD and a gold-standard for symptom control. Nonetheless, a significant majority of PD patients develop motor fluctuations over their disease course, with a significant impact on quality-of-life, meaning control of such complications translates into a fundamental clinical need. Catechol-O-methyl transferase (COMT) inhibitors (COMT-i) are used as first-line adjuvant therapy to L-dopa for end-of-dose (EoD) motor fluctuations, since they increase L-dopa availability in the brain by inhibiting its peripheral metabolism. Opicapone (OPC), a once-daily, long-acting COMT-i, is the most recent and potent of its class, having been licensed in Europe in 2016 as an add-on to preparations of L-dopa/DOPA decarboxylase inhibitors in PD patients with EoD motor fluctuations. More recently, it has also received approval in the USA and Japan in 2020. Two high-quality positive efficacy studies (double-blind Phase III clinical trials) established OPC efficacy with significant reduction in OFF time (average 60 minutes vs placebo), without concomitant increase of distressing dyskinesias during ON time. These beneficial effects were sustained in open-label extension studies, without unexpected safety issues or adverse events, with dyskinesia having been the most frequent complaint. OPC also avoids liver toxicity and gastrointestinal issues compared with previous COMT-i. In this review, we aimed to cover OPC’s lifecycle (synthesis to commercialization), its clinical pharmacological data, safety, tolerability and pharmacovigilance evidence, and discuss its role in the management of motor fluctuations in PD as well as its emerging place in international recommendations.

Pharmacokinetics of Opicapone and Its Metabolites in Healthy White and Chinese Subjects

Opicapone (OPC) is a third-generation catechol-O-methyltransferase inhibitor developed to treat Parkinson disease and motor fluctuations. This open-label, single-center, phase 1 study aimed to evaluate the pharmacokinetics (PK) of OPC and its metabolites when administered as single and multiple doses in healthy White and Chinese subjects. The study enrolled a total of 30 White and Chinese healthy subjects, equally balanced among groups. The first dose of OPC was administered orally as a single dose of 50 mg on day 1, followed by a 10-day once-daily treatment from day 5 to day 14. Plasma concentrations of OPC and its metabolites were measured at 0 to 72 and 0 to 144 hours after dosing for single dose and multiple dose, respectively. Moreover, urine concentrations of OPC and its metabolite were measured 0 to 24 hours after dosing. PK parameters were derived from noncompartmental analysis. Geometric mean ratios and 90% confidence intervals for the main PK parameters were conducted to evaluate the ethnic difference between White and Chinese subjects. The plasma and urine exposure of OPC and its metabolites in Chinese subjects were similar to those in White subjects. These results indicated that ethnicity had no significant impact on PK of OPC between White and Chinese subjects.

Opicapone for Parkinson's disease: clinical evidence and future perspectives

Since 2016, opicapone (OPC), a potent third-generation, long-acting, once-daily, peripheral catechol-O-methyltransferase inhibitor, is approved as an add-on to levodopa in Parkinson's disease patients with motor fluctuations. OPC 50 mg has showed to be able in reducing OFF time by an average of about 60 min daily compared with placebo, to further reduce OFF-time of about 39 min, when switched from ENT to OPC and to be safe. These beneficial effects of OPC were maintained for 1 year. Recently, several post hoc analysis and few pilot observational open-label studies, have suggested its efficacy and wider applicability for different phenotypes of motor complications and for Parkinson's disease stages. Here we review OPC applicability and perspectives, in the light of the more recently published analysis.

Cost-effectiveness of opicapone and entacapone in reducing OFF-time in Parkinson's disease patients treated with levodopa/carbidopa

AIMS

To assess from a US payer perspective the relative cost-effectiveness of the catechol-O-methyltransferase inhibitors opicapone and entacapone when used adjunctively to levodopa/carbidopa (LD/CD) in patients with Parkinson's disease (PD), based on the drugs' effects to reduce absolute OFF-time hours in PD patients.

MATERIALS AND METHODS

A Markov model was created to estimate cost-effectiveness of adjunctive opicapone treatment compared with adjunctive entacapone treatment in a synthetic cohort of 1,000 patients with PD taking LD/CD. Clinical inputs were derived from clinical trials, published literature, and expert opinion. Cost data (in 2018 US dollars) were obtained from the Centers for Medicare & Medicaid Services, the Kaiser Family Foundation, and Analy$ource. Cost-effectiveness outcomes included incremental cost per OFF-time hours avoided, cost per life year gained, and cost per quality-adjusted life year (QALY) gained. Outcomes were projected over a 25-year lifetime horizon and discounted at 3% annually.

RESULTS

Opicapone treatment was associated with an average of 1,187 fewer OFF-time hours per patient and an increase of 0.07 QALYs compared with entacapone. Total lifetime costs for opicapone were $3,100 higher than entacapone, resulting in an incremental cost-effectiveness ratio of $46,900 per QALY. One-way sensitivity analyses showed the model was most sensitive to mean OFF-time hours associated with opicapone and entacapone. Probabilistic sensitivity analysis suggested a 60-65% probability that opicapone was cost-effective relative to entacapone at any willingness-to-pay threshold ≥$5,000.

LIMITATIONS

There exists a single head-to-head clinical trial comparing the effectiveness of opicapone with entacapone, thus the clinical inputs regarding relative treatment effect of the drugs to reduce OFF-time hours in PD patients receiving LD/CD were derived from that single non-inferiority trial.

CONCLUSIONS

Add-on treatment with opicapone in PD patients receiving LD/CD appeared to be cost-effective compared with entacapone.

Opicapone (Ongentys): A New COMT Inhibitor for the Treatment of Parkinson's Disease

OBJECTIVE

To describe the safety and efficacy of opicapone, a newly Food and Drug Administration-approved catechol-O-methyltransferase (COMT) inhibitor, as an adjunctive treatment to levodopa/carbidopa in patients with Parkinson's disease (PD) experiencing off episodes.

DATA SOURCES

A literature search through PubMed and International Pharmaceutical Abstracts (January 2000 to October 2020) was conducted using the following search terms: Ongentys, opicapone, COMT inhibitor, Parkinson's disease, and Parkinson's.

STUDY SELECTION AND DATA EXTRACTION

Articles selected included those describing preclinical and clinical studies examining the pharmacokinetics, efficacy, and/or safety of opicapone.

DATA SYNTHESIS

In preclinical trials, opicapone demonstrated marked S-COMT inhibition, despite its short half-life, while maintaining an acceptable safety and efficacy profile. Results from phase 3 clinical trials further supported the safety and efficacy of opicapone as an adjunct to levodopa. In addition, opicapone, at a dose of 50 mg once daily, was shown to be superior to placebo and noninferior to entacapone in reducing time spent in the off state. Adverse effects commonly reported with opicapone include dyskinesias, constipation, hypotension/syncope, increased blood creatine kinase, and decreased weight.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Additional medications, such as COMT inhibitors, become necessary adjunctive treatments as the disease progresses. Compared to other COMT inhibitors currently on the US market, opicapone offers the advantage of once-daily dosing.

CONCLUSION

Opicapone is a safe and effective COMT inhibitor shown to reduce off episodes in patients with PD.

Opicapone Efficacy and Tolerability in Parkinson's Disease Patients Reporting Insufficient Benefit/Failure of Entacapone

BACKGROUND

Opicapone, a recently introduced catechol-o-methyl transferase (COMT) inhibitor has the advantage of being administered once daily, and has pharmacokinetic data to indicate it offers a greater degree of COMT inhibition than entacapone. Although trial data indicate it is non-inferior to entacapone, there are no data to indicate whether it offers any clinical advantages.

METHODS

In this audit, we present data from 57 individuals prescribed opicapone at the National Hospital for Neurology and Neurosurgery, Queen Square who had either not tolerated or reported insufficient benefit following previous prescription of entacapone.

RESULTS

A total of 20 of 57 patients switched directly from entacapone to opicapone ("entacapone switchers") whereas 37 of 57 patients had previously discontinued entacapone because of lack of benefit or adverse events ("entacapone failures"). A total of 21 of 57 (37%) patients stopped opicapone prior to 6 months. A total of 7 of 20 (35%) "entacapone switchers" experienced adverse events with opicapone of which 5 stopped the drug prior to the 6 month evaluation of efficacy. A total of 23 of 37 (62%) "entacapone failures" reported adverse events of which 16 stopped the drug. Among 36 of 57 (63%) patients who continued to use opicapone at 6 months, there was an improvement in OFF time of ~2 hours per day as measured by interview.

CONCLUSIONS

We conclude that opicapone can be an effective additional treatment for wearing off in Parkinson's disease (PD) in a subgroup of patients. The use of opicapone in our cohort with prior entacapone exposure, however, was associated with higher rates of adverse effects and treatment discontinuation than reported in published trial data of COMT inhibitor naïve patients.

Randomized, Controlled Study of Opicapone in Japanese Parkinson's Patients with Motor Fluctuations

Objectives

This placebo‐controlled, randomized study evaluated the efficacy and safety of opicapone 25‐mg and 50‐mg tablets in Japanese levodopa‐treated patients with Parkinson's disease and motor fluctuations.

Methods

Japanese adults (n = 437, age 39–83 years) with Parkinson's disease (United Kingdom Parkinson's Disease Society criteria) received opicapone 25‐mg (n = 145), opicapone 50‐mg (n = 145), or placebo (n = 147) tablets over the double‐blind treatment period (14–15 weeks). The primary efficacy assessment was change in OFF‐time; secondary efficacy assessments included OFF/ON‐time responders (≥1 hour change from baseline), total ON‐time, ON‐time with and without troublesome dyskinesia, and Unified Parkinson's Disease Rating Scale.

Results

The least squares mean (standard error) change in OFF‐time from baseline to the last visit was −0.42 (0.21) hour for the placebo group, −1.16 (0.22) hour for the opicapone 25 mg group, and −1.04 (0.21) hour for the opicapone 50 mg group. The percentage of ON‐time responders, changes in total ON‐time/ON‐time without troublesome dyskinesia, and Unified Parkinson's Disease Rating Scale II (at OFF) all showed statistically significant improvements versus placebo for both opicapone tablet doses (P < 0.05). Unified Parkinson's Disease Rating Scale III (at ON) was improved versus placebo in patients who received opicapone 50 mg (P < 0.05). Adverse events were more common in patients treated with opicapone 25 mg (60.0%) or opicapone 50 mg (54.5%) versus placebo (48.3%). The most commonly reported adverse event was dyskinesia (placebo, 2.7%; opicapone 25 mg, 9.0%; opicapone 50 mg, 12.4%).

Conclusions

In Japanese patients, both opicapone 25 and 50 mg were significantly more effective than placebo with no dose‐dependent difference in efficacy, and both doses were well tolerated. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Safety Profile of Opicapone in the Management of Parkinson's Disease

BACKGROUND

Opicapone is a catechol O-methyltransferase (COMT) inhibitor indicated for use as adjunct to levodopa therapy in patients with Parkinson's disease (PD) and motor fluctuations.

OBJECTIVE

To characterize the safety and tolerability of adjunct opicapone (25 and 50 mg) in a pooled population of levodopa-treated PD patients who participated in the opicapone Phase-3 clinical program.

METHODS

Patient-level data (placebo, opicapone 25 mg and 50 mg) from the BIPARK-1 and BIPARK-2 double-blind and open-label studies were combined.

RESULTS

Pooled analyses included 766 patients from the double-blind studies and 848 patients from the open-label studies. In the double-blind studies, 63.3% of opicapone-treated patients reported treatment-emergent adverse events (TEAEs) versus 57.2% in the placebo group. The most common TEAEs reported in the opicapone group compared to placebo were dyskinesia, constipation and insomnia. The incidence of serious TEAEs was similar across opicapone and placebo groups (3.5% versus 4.3%, respectively). Overall, 71.3% patients treated with open-label opicapone reported at least one TEAE; most occurred within the first 2 months of the open-label studies, and then decreased thereafter. Throughout the Phase-3 clinical program, there were no serious AEs suggestive of hepatic toxicity, and the incidence of gastrointestinal disorders such as nausea and diarrhea remained low (<2%). There were no relevant changes in laboratory parameters including liver enzymes, vital signs, physical or neurological examinations, or ECG readings.

CONCLUSIONS

Long-term use of opicapone once-daily over 1-year at doses of 25 mg or 50 mg was generally safe and well tolerated, supporting its clinical usefulness in the management of PD motor fluctuations.

Safinamide in the treatment of Parkinson's disease

The deficiency pattern of neurotransmitters is heterogeneous in patients with Parkinson's disease. Consequence is an individual variable expression of motor and nonmotor features. They respond to agents with a broader spectrum of mode of actions, whereas dopamine substitution only targets impaired motor behavior. The pharmacological profile of safinamide includes reversible monoamine oxidase B inhibition and modulation of voltage-dependent sodium- and calcium channels with consecutive decline of glutamate release. Safinamide improves motor and nonmotor symptoms. Combination of safinamide with the catechol-O-methyltransferase inhibitor opicapone in one capsule is a promising future treatment alternative, which simplifies drug therapy in Parkinson's disease. Both agents complement each other in terms of application mode and efficacy on motor complications as adjuncts to levodopa therapy.

Pharmacokinetic Comparison of Capsule and Tablet Formulations of Opicapone in Healthy Japanese Subjects: Phase 1 Study

Opicapone, a peripheral, long‐acting catechol‐O‐methyltransferase inhibitor has been shown to improve wearing‐off phenomenon in randomized, double‐blind studies. This study compared the pharmacokinetic characteristics of opicapone small‐tablet and size 1 capsule formulations after single oral administration to healthy Japanese subjects. In this open‐label, randomized, 2‐way and 2‐period crossover phase 1 study, 48 healthy male subjects (aged 20 to 45 years; body mass index, 18.5 to <30.0 kg/m²) were randomly assigned to 2 cohorts (n = 24 each), which were administered opicapone 25 or 50 mg in a tablet‐capsule or capsule‐tablet sequence under fasted conditions. Blood samples were collected for pharmacokinetic analysis before opicapone capsule/tablet administration and at regular intervals over 24 hours after administration. Compared with capsules, tablets were associated with higher C_max and AUC_last/0‐∞ values. However, t_1/2 and t_max values were similar with opicapone 25‐ and 50‐mg capsules/tablets. Geometric mean ratios (tablets/capsules) of C_max, AUC_last, and AUC_0‐∞ were 1.24, 1.18, and 1.19, respectively, for the 25‐mg dose and 1.42, 1.28, and 1.27, respectively, for the 50‐mg dose. Opicapone was well tolerated, and no serious adverse events occurred. A small tablet formulation of opicapone proposed for use in Japanese clinical trials was associated with apparent greater exposure compared with the existing hard capsule formulation, which should be considered when developing opicapone for Japanese patients.

Effect of Opicapone Tablets on Levodopa and 3-O-Methyldopa Pharmacokinetics in Healthy Japanese Subjects: Phase 1 Study

This study evaluated the effect of a small-tablet formulation of opicapone for use in clinical trials in Japan on the pharmacokinetics of levodopa (l-dopa) and 3-O-methyldopa (3-OMD). In an open-label, 3-period, single-sequence crossover phase 1 study in 80 healthy Japanese males (aged 20-45 years; body mass index, 18.5 to <30.0 kg/m² ), 10 mg of l-dopa/carbidopa 100 was administered 3 times daily on day 0 (period 1) and day 12 (period 3), and opicapone tablets (5, 10, 25, or 50 mg; n = 20 each group) were administered once daily for 11 days (period 2). During periods 1 and 3, plasma concentrations of l-dopa and 3-OMD were measured and pharmacokinetic parameters (maximum observed plasma concentration, time at which maximum concentration was observed, area under the plasma concentration-time curve from time 0 to 5 hours [AUC_5h ] and from time 0 to 24 hours [AUC_24h ] following each dose, terminal half-life) of plasma l-dopa and 3-OMD were determined along with the geometric mean ratio (period 3/period 1) of AUC_24h for l-dopa and 3-OMD. Maximum concentration of l-dopa for the first, second, or third doses of l-dopa/carbidopa did not significantly increase with increasing opicapone dose. The AUC of l-dopa increased with increasing opicapone dose but tended toward a peak plateau with opicapone doses of 25 mg and higher. Geometric mean ratios (90% confidence intervals) of AUC_24h were 5 mg, 1.16 (1.10-1.21); 10 mg, 1.26 (1.23-1.30); 25 mg, 1.51 (1.44-1.57); 50 mg, 1.60 (1.54-1.66). Opicapone tablets were well tolerated. In Japanese healthy subjects, increases in plasma exposure to l-dopa appear to level off with opicapone doses of 25 mg and higher, which may be relevant for optimal dosing among Japanese patients with Parkinson disease.

Long-term efficacy of opicapone in fluctuating Parkinson's disease patients: a pooled analysis of data from two phase 3 clinical trials and their open-label extensions

BACKGROUND AND PURPOSE

The aim was to evaluate the efficacy of the catechol-O-methyltransferase inhibitor opicapone (25 and 50 mg) as adjunct therapy to levodopa in a pooled population of Parkinson's disease patients who participated in the pivotal double-blind trials of opicapone and their 1-year open-label extensions.

METHODS

Data (placebo, opicapone 25 mg and opicapone 50 mg) from the BIPARK-1 and BIPARK-2 double-blind and open-label studies were combined. The studies had similar designs, eligibility criteria and assessment methods. The primary efficacy variable in both double-blind studies was the change from baseline in absolute OFF time based on patient diaries.

RESULTS

Double-blind treatment with opicapone (25 and 50 mg) significantly reduced absolute daily OFF time from a baseline of 6.1-6.6 h. The mean (and 95% confidence interval) treatment effect versus placebo was -35.1 (-62.1, -8.2) min (P = 0.0106) for the 25 mg dose and -58.1 (-84.5, -31.7) min (P < 0.0001) for the 50 mg dose. Reductions in OFF time were mirrored by significant increases in ON time without troublesome dyskinesia (P < 0.05 and P < 0.0001 for the 25 and 50 mg doses, respectively). No significant differences were observed for ON time with troublesome dyskinesia. Patient diary results from the open-label phase indicated a maintenance of effect for patients previously treated with opicapone 50 mg. The group previously treated with the 25 mg dose benefitted with further optimization of therapy during the open-label phase, whilst switching from placebo to opicapone led to significant reductions in OFF time and increased ON time.

CONCLUSIONS

Over at least 1 year of open-label therapy, opicapone consistently reduced OFF time and increased ON time without increasing the frequency of troublesome dyskinesia.

Opicapone for the treatment of Parkinson's disease: A review of a new licensed medicine

Catechol-O-methyl transferase inhibitors are currently used as first-line add-on therapy to levodopa for the treatment of end-of-dose motor fluctuations in Parkinson's disease patients, as they increase levodopa bioavailability. Several factors hamper the use of current available catechol-O-methyl transferase inhibitors, that is, the moderate efficacy and multiple dosing for entacapone and the risk of liver toxicity with tolcapone. Opicapone, a new long-acting, peripherally selective, once-daily catechol-O-methyl transferase inhibitor, was recently licensed in Europe. Two phase 3 double-blind clinical trials demonstrated opicapone efficacy in reducing OFF time by an average of about 60 minutes daily compared with placebo, without increasing ON time with troublesome dyskinesias. These effects were also maintained during a subsequent open-label extension consisting of 1-year follow-up. Opicapone showed a good safety profile. From June 2016, Opicapone received the approval for marketing authorization from the European Commission as adjunctive therapy to levodopa/DOPA decarboxylase inhibitors in patients with PD and end-of-dose motor fluctuations. We aimed to review the clinical pharmacological data of opicapone, summarize its clinical efficacy and safety issues, and discuss its potential role in the management of Parkinson's disease. © 2018 International Parkinson and Movement Disorder Society.

Noninvasive options for 'wearing-off' in Parkinson's disease: a clinical consensus from a panel of UK Parkinson's disease specialists

In the past 4 years, two adjunctive treatment options to levodopa have been licensed for use in the UK in patients with Parkinson's disease (PD) and motor fluctuations: opicapone, a third-generation catechol-O-methyl transferase inhibitor, and safinamide, a monoamine oxidase B inhibitor. This clinical consensus outlines the practical considerations relating to motor fluctuations and managing wearing-off in patients with PD, and provides a clinical insight to adjunctive treatment options, including opicapone and safinamide. Practice-based opinion was provided from a multidisciplinary steering Group of eight UK-based movement disorder and PD specialists, including neurologists, geriatricians and a nurse specialist, from England, Scotland and Wales.

Effect of opicapone multiple-dose regimens on levodopa pharmacokinetics

AIMS

To compare the levodopa/carbidopa (LC) and levodopa/benserazide (LB) pharmacokinetic profiles following repeated doses of opicapone (OPC) administered apart from levodopa.

METHODS

Two randomized, double blind, sex-balanced, placebo-controlled studies in four groups of 12 or 18 healthy subjects each. In each group, enrolled subjects received a once-daily morning (5, 15 and 30 mg) or evening (5, 15 and 50 mg) administration of OPC or placebo for up to 28 days. On the morning of Day 11, 12 h after the OPC or placebo evening dose, or the morning of Day 21, 1 h after the OPC or placebo dose, a single dose of immediate-release 100/25 mg LC was administered. Similarly, on Day 18 morning, 12 h after the OPC or placebo evening dose, or Day 28 morning, 1 h after the OPC or placebo dose, a single dose of immediate-release 100/25 mg LB was administered.

RESULTS

All OPC treatments, in relation to the placebo group, presented a higher extent of exposure (AUC) to levodopa following either LC or LB doses. A relevant but not dose-dependent increase in the levodopa AUC occurred with all OPC dose groups in relation to placebo. All active treatments significantly inhibited both peak (Emax ) and extent (AUEC) of the catechol-O-methyltransferase activity in relation to placebo. The tolerability profile was favourable.

CONCLUSION

Opicapone, as once-daily oral evening regimen and/or 1 h apart from levodopa therapy, increases the bioavailability of levodopa associated with its pronounced, long-lasting and sustained catechol-O-methyltransferase inhibition. The tolerability profile was favourable and similar between OPC and placebo.

Spotlight on opicapone as an adjunct to levodopa in Parkinson's disease: design, development and potential place in therapy

Parkinson's disease (PD) is a progressive, chronic, neurodegenerative disease characterized by rigidity, tremor, bradykinesia and postural instability secondary to dopaminergic deficit in the nigrostriatal system. Currently, disease-modifying therapies are not available, and levodopa (LD) treatment remains the gold standard for controlling motor and nonmotor symptoms of the disease. LD is extensively and rapidly metabolized by peripheral enzymes, namely, aromatic amino acid decarboxylase and catechol-O-methyltransferase (COMT). To increase the bioavailability of LD, COMT inhibitors are frequently used in clinical settings. Opicapone is a novel COMT inhibitor that has been recently approved by the European Medicines Agency as an adjunctive therapy to combinations of LD and aromatic amino acid decarboxylase inhibitor in adult PD patients with end-of-dose motor fluctuations. We aimed to review the biochemical properties of opicapone, summarize its preclinical and clinical trials and discuss its future potential role in the treatment of PD.

Effect of 3 Single-Dose Regimens of Opicapone on Levodopa Pharmacokinetics, Catechol-O-Methyltransferase Activity and Motor Response in Patients With Parkinson Disease

This study determined the effects of single doses of opicapone (OPC), a novel third-generation catechol-O-methyltransferase (COMT) inhibitor, on levodopa and 3-O-methyl-levodopa (3-OMD) pharmacokinetics (PK), COMT activity and motor fluctuations in patients with Parkinson disease (PD). Subjects received, in a double-blind manner, 25, 50, and 100 mg OPC or placebo (PLC) in 4 separate treatment periods. The washout period between doses was at least 10 days. During each period, the OPC/PLC capsules were to be coadministered with the morning dose of 100/25 mg levodopa/carbidopa (LC) or levodopa/benserazide (LB) on day 3. In relation to PLC, levodopa exposure increased 3.7%, 16.4%, and 34.8% following 25, 50, or 100 mg OPC, respectively. Maximum S-COMT inhibition (Emax ) ranged from 67.8% (25 mg OPC) to 100% (100 mg OPC). Peak and extent of S-COMT inhibition were dose-dependent. Maximum decrease in the plasma 3-OMD was observed following administration of 100 mg OPC. Opicapone administered concomitantly with standard-release 100/25 mg LC or LB improved motor performance. Treatments were generally well tolerated and safe. It was concluded that OPC is a new COMT inhibitor that significantly decreased COMT activity and increased systemic exposure to levodopa in PD patients with motor fluctuations.

Opicapone pharmacokinetics and pharmacodynamics comparison between healthy Japanese and matched white subjects

Opicapone (OPC) is a novel third-generation catechol-O-methyltransferase (COMT) inhibitor. This randomized, double-blind, parallel, placebo-controlled and multiple ascending dose study in 3 sequential groups of up to 38 (19 Japanese plus 19 white subjects) aimed to compare the pharmacokinetics (PK) and pharmacodynamics (PD; COMT activity) of opicapone between healthy Japanese and matched white subjects. Enrolled subjects received a once-daily morning administration of OPC (5, 25, or 50 mg) or placebo for 10 days, with plasma and urine concentrations of opicapone and its metabolites measured up to 144 hours postdose, including S-COMT activity. Geometric mean ratios (GMRs) and confidence intervals (95%CIs) for the main PK and PD parameters of OPC were evaluated between populations. Both the PK and PD of OPC were similar in the Japanese and white populations. Overall, only minimal differences were noted between the 2 populations, which were not deemed to be statistically significant. When both populations were separated based on their COMT genotype, the observed PK and PD differences were also negligible. In conclusion, the PK and PD profiles of OPC were similar in the Japanese and white populations. Thus, ethnicity and COMT polymorphisms had no significant impact on the OPC PK and PD in the conditions of the study.

Evaluation of opicapone on cardiac repolarization in a thorough QT/QTc study

Opicapone, a novel third-generation catechol-O-methyltransferase inhibitor for use as adjunctive therapy in levodopa-treated Parkinson's disease patients, was investigated on cardiac repolarization in healthy adult volunteers. This was a single-center, randomized, double-blind, placebo-controlled, open-label active-controlled, 4-period crossover study conducted in 64 subjects. In each period, subjects received a single oral dose of 50 mg opicapone, 800 mg opicapone, placebo, or 400 mg moxifloxacin and 24-hour 12-lead Holter monitoring was performed on day -1 (baseline) and after each single dose. After a single oral administrations of 50 and 800 mg opicapone, opicapone was the major entity in the circulation, with a median tmax of 1.5-2.0 hours. Opicapone was rapidly eliminated, with an elimination half-life of 1-2 hours. There was no clinically relevant effect of 50 and 800 mg opicapone versus placebo on cardiac depolarization or repolarization. All upper bounds of the 1-sided 95% confidence interval (CI) were below 10 milliseconds, confirming that opicapone has no QT-prolonging effect. Moxifloxacin caused an increase in the QTcI, with a lower bound of the 2-sided 95% CI always higher than 5 milliseconds, around the tmax of peak concentration, demonstrating assay sensitivity. In conclusion, administration of opicapone at therapeutic (50 mg) and supratherapeutic (800 mg) doses did not induce a clinically significant prolongation of the QTc interval.

Opicapone: a short lived and very long acting novel catechol-O-methyltransferase inhibitor following multiple dose administration in healthy subjects

AIMS

The aim of this study was to assess the tolerability, pharmacokinetics and inhibitory effect on erythrocyte soluble catechol-O-methyltransferase (S-COMT) activity following repeated doses of opicapone.

METHODS

This randomized, placebo-controlled, double-blind study enrolled healthy male subjects who received either once daily placebo or opicapone 5, 10, 20 or 30 mg for 8 days.

RESULTS

Opicapone was well tolerated. Its systemic exposure increased in an approximately dose-proportional manner with an apparent terminal half-life of 1.0 to 1.4 h. Sulphation was the main metabolic pathway. Opicapone metabolites recovered in urine accounted for less than 3% of the amount of opicapone administered suggesting that bile is likely the main route of excretion. Maximum S-COMT inhibition (Emax ) ranged from 69.9% to 98.0% following the last dose of opicapone. The opicapone-induced S-COMT inhibition showed a half-life in excess of 100 h, which was dose-independent and much longer than plasma drug exposure. Such a half-life translates into a putative underlying rate constant that is comparable with the estimated dissociation rate constant of the COMT-opicapone complex.

CONCLUSION

Despite its short elimination half-life, opicapone markedly and sustainably inhibited erythrocyte S-COMT activity making it suitable for a once daily regimen.