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.

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 [14 C]-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.

Opicapona para el tratamiento de la enfermedad de Parkinson: datos de vida real en España / Opicapone for the treatment of Parkinson's disease: real-life data in Spain

La opicapona es un inhibidor de la catecol-O-metiltransferasa (iCOMT) autorizado en Europa en 2016 como terapia adyuvante a las preparaciones de levodopa/inhibidores de la dopa descarboxilasa en pacientes adultos con enfermedad de Parkinson y fluctuaciones motoras de final de dosis que no puedan ser estabilizados con esas combinaciones. La eficacia de la opicapona en estos pacientes ha sido demostrada en dos ensayos clínicos pivotales, BIPARK I y BIPARK II, en los que se ha demostrado la superioridad frente al placebo y la no inferioridad frente a la entacapona. A pesar de que constituyen el estándar para la evaluación de intervenciones, los ensayos clínicos aleatorizados presentan limitaciones de validez externa debidas a la utilización de criterios estrictos de elegibilidad. Por tanto, se considera necesario disponer de una evaluación más amplia de la eficacia general del fármaco, complementando la información de los ensayos clínicos aleatorizados con estudios de ‘vida real o práctica clínica real’. El objetivo de esta revisión ha sido recopilar y poner en perspectiva la información disponible sobre los resultados de la opicapona en estudios de práctica clínica real en España. Los datos acumulados en España con opicapona en 18 series con más de 1.000 pacientes confirman la seguridad y la eficacia de este iCOMT comunicadas previamente. Además, muestran que la opicapona es especialmente útil en pacientes en un estadio de la enfermedad menos avanzado y fluctuaciones motores leves, lo que sugeriría una mejor relación beneficio-riesgo cuanto más temprana sea su introducción en el esquema terapéutico para el tratamiento de las fluctuaciones motoras.(AU)

Opicapone is a catechol-O-methyl-transferase (iCOMT) inhibitor authorized in Europe in 2016 and indicated as adjunctive therapy to preparations of levodopa/ DOPA decarboxylase inhibitors in adult patients with Parkinson’s disease and end-of-dose motor fluctuations who cannot be stabilised on those combinations. The efficacy of opicapone in these patients has been demonstrated in two pivotal randomized clinical trials, BIPARK I and BIPARK II, in which it has demonstrated its superiority versus placebo and non-inferiority versus entacapone. Although they constitute the gold standard for the evaluation of interventions, randomized clinical trials present limitations of external validity due to the use of strict eligibility criteria. Therefore, it is considered necessary to have a more comprehensive evaluation of the efficacy of the drug, complementing the information obtained from randomized clinical trials with that of “real world or real clinical practice” studies. The objective of this review has been to collect and put into perspective the information available on opicapone coming from real clinical practice studies in Spain. The data from Spain with opicapone in 18 series with more than 1,000 patients in total, confirm the safety and efficacy previously reported with this iCOMT. Furthermore, they show that opicapone is especially useful in patients with a less advanced stage of the disease and mild motor fluctuations, which would suggest that the earlier its introduction in the therapeutic scheme for the management of motor fluctuations, the better is the benefit-risk ratio for the drug.(AU)

Opicapone: A Review in Parkinson's Disease.

Oral opicapone (Ongentys®), a potent third-generation, peripheral catechol-O-methyltransferase (COMT) inhibitor, is approved as adjunctive therapy to preparations of levodopa/dopa-decarboxylase inhibitor (L-dopa/DDCI) in adults with Parkinson's disease (PD) and end-of dose (EoD) motor fluctuations. In pivotal global trials (BIPARK 1 and BIPARK 2; 14-15 weeks' duration), open-label extensions (OLEs) of BIPARK, and in the real-world setting (OPTIPARK; 3-6 months), opicapone 50 mg once daily was an effective and generally well tolerated adjunctive therapy to L-dopa/DDCI plus other PD therapy in adults with PD and EoD motor fluctuations. Adjunctive opicapone provided better efficacy than placebo for improvements in ON- and OFF-state time and fulfilled noninferiority to adjunctive entacapone for improvements in OFF time in BIPARK 1. These beneficial effects of adjunctive opicapone on motor fluctuations were maintained during 1 year of treatment in OLE studies. Given its efficacy and safety profile, adjunctive opicapone remains an important option in the management of adults with PD and EoD motor fluctuations who cannot be stabilized on preparations of L-dopa/DDCI.

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 Cmax and AUClast/0-∞ values. However, t1/2 and tmax values were similar with opicapone 25- and 50-mg capsules/tablets. Geometric mean ratios (tablets/capsules) of Cmax , AUClast , and AUC0-∞ 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 [AUC5h ] and from time 0 to 24 hours [AUC24h ] 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 AUC24h 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 AUC24h 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.

Medical Management and Prevention of Motor Complications in Parkinson's Disease.

Levodopa is the most effective medication for the treatment of the motor symptoms of Parkinson's disease. However, over time, the clinical response to levodopa becomes complicated by a reduction in the duration and reliability of motor improvement (motor fluctuations) and the emergence of involuntary movements (levodopa-induced dyskinesia). Strategies that have been attempted in an effort to delay the development of these motor complications include levodopa sparing and continuous dopaminergic therapy. Once motor complications occur, a wide array of medical treatments is available to maximize motor function through the day while limiting dyskinesia. Here, we review the clinical features, epidemiology, and risk factors for the development of motor complications, as well as strategies for their prevention and medical management.

Optimized clinical management of Parkinson's disease with opicapone. Recommendations from Spanish experts. / Optimización del manejo clínico de opicapona en la enfermedad de Parkinson. Recomendaciones de expertos españoles.

Motor fluctuations are frequently seen in Parkinson disease patients on chronic treatment with levodopa. Management of motor fluctuation includes the addition of catechol-O-methyl transferase (COMT) inhibitors. Opicapone is a recent and selective third-generation COMT inhibitor which achieves marked increase in the bioavailability of levodopa. We present a consensus of a group of Spanish neurologists with extensive experience in the clinical management of motor fluctuations. The clinical experience of this group of experts is in line with clinical trials and confirms that opicapone is an effective drug in the control of motor fluctuations, regardless of the daily levodopa dose, or the use of other antiparkinsonian drugs. However, in the opinion of these experts, the ideal patient with Parkinson's disease to initiate treatment with opicapone is the one with mild motor fluctuations, since the ratio between clinical efficacy and adverse effects is more favorable. In general, it is an easy-to-use drug both in those first treated with a COMT inhibitor or those already on entacapone. In any case, the secondary side effects are easily managed.

TITLE: Optimización del manejo clínico de opicapona en la enfermedad de Parkinson. Recomendaciones de expertos españoles.Las fluctuaciones motoras constituyen una importante complicación en los pacientes con enfermedad de Parkinson tratados con levodopa. Entre las opciones terapéuticas para el manejo de las fluctuaciones motoras se cuenta con los inhibidores de la catecol-O-metil-transferasa (COMT), incluyendo la opicapona. La opicapona muestra una elevada afinidad por la COMT y consigue un aumento marcado de la biodisponibilidad de la levodopa. Se presenta el consenso de un grupo de expertos españoles en la enfermedad de Parkinson con experiencia en el tratamiento clínico de fluctuaciones motoras y el empleo de opicapona. La experiencia de este grupo de expertos, en consonancia con los ensayos clínicos, confirma que la opicapona es un fármaco eficaz en el control de las fluctuaciones motoras de la enfermedad de Parkinson, con independencia de la dosis de levodopa recibida o de la utilización de otros fármacos antiparkinsonianos. No obstante, a juicio de estos expertos, el paciente ideal para iniciar el tratamiento con opicapona es el que presenta fluctuaciones motoras leves, ya que muestra una mejor relación entre eficacia clínica y efectos adversos. En general, la opicapona es un fármaco de fácil manejo, tanto en pacientes que requieren opicapona como primer inhibidor de la COMT como en los previamente tratados con entacapona, o en los que están en tratamiento concomitante con otros fármacos antiparkinsonianos. En cualquier caso, los efectos secundarios son fácilmente corregibles.

Opicapone and Levodopa-Carbidopa Intestinal Gel Infusion: The Way Forward Towards Cost Savings for Healthcare Systems?

Combined catechol-O-methyl-transferase-inhibition and Levodopa-Carbidopa intestinal gel (LCIG) infusion has the potential to reduce LCIG daily dose and the costs of this therapy. In this retrospective analysis, we report on Parkinson's disease (PD) patients on LCIG with concomitant Opicapone. In 11 patients, the introduction of Opicapone led to LCIG daily dose being reduced by 24.8% (p = 0.05) without any significant worsening of dyskinesia. Three patients withdrew from Opicapone due to side effects or inefficacy. LCIG daily dose reduction could lead to cost savings of £142,820.63/year in the United Kingdom while maintaining clinical care.

Optimización del manejo clínico de opicapona en la enfermedad de Parkinson. Recomendaciones de expertos españoles / Optimized clinical management of Parkinson’s disease with opicapone. Recommendations from Spanish experts

Las fluctuaciones motoras constituyen una importante complicación en los pacientes con enfermedad de Parkinson tratados con levodopa. Entre las opciones terapéuticas para el manejo de las fluctuaciones motoras se cuenta con los inhibidores de la catecol-O-metil-transferasa (COMT), incluyendo la opicapona. La opicapona muestra una elevada afinidad por la COMT y consigue un aumento marcado de la biodisponibilidad de la levodopa. Se presenta el consenso de un grupo de expertos españoles en la enfermedad de Parkinson con experiencia en el tratamiento clínico de fluctuaciones motoras y el empleo de opicapona. La experiencia de este grupo de expertos, en consonancia con los ensayos clínicos, confirma que la opicapona es un fármaco eficaz en el control de las fluctuaciones motoras de la enfermedad de Parkinson, con independencia de la dosis de levodopa recibida o de la utilización de otros fármacos antiparkinsonianos. No obstante, a juicio de estos expertos, el paciente ideal para iniciar el tratamiento con opicapona es el que presenta fluctuaciones motoras leves, ya que muestra una mejor relación entre eficacia clínica y efectos adversos. En general, la opicapona es un fármaco de fácil manejo, tanto en pacientes que requieren opicapona como primer inhibidor de la COMT como en los previamente tratados con entacapona, o en los que están en tratamiento concomitante con otros fármacos antiparkinsonianos. En cualquier caso, los efectos secundarios son fácilmente corregibles

Motor fluctuations are frequently seen in Parkinson disease patients on chronic treatment with levodopa. Management of motor fluctuation includes the addition of catechol-O-methyl transferase (COMT) inhibitors. Opicapone is a recent and selective third-generation COMT inhibitor which achieves marked increase in the bioavailability of levodopa. We present a consensus of a group of Spanish neurologists with extensive experience in the clinical management of motor fluctuations. The clinical experience of this group of experts is in line with clinical trials and confirms that opicapone is an effective drug in the control of motor fluctuations, regardless of the daily levodopa dose, or the use of other antiparkinsonian drugs. However, in the opinion of these experts, the ideal patient with Parkinson’s disease to initiate treatment with opicapone is the one with mild motor fluctuations, since the ratio between clinical efficacy and adverse effects is more favorable. In general, it is an easy-to-use drug both in those first treated with a COMT inhibitor or those already on entacapone. In any case, the secondary side effects are easily managed

The preclinical discovery and development of opicapone for the treatment of Parkinson's disease.

INTRODUCTION: Opicapone (OPC) is a well-established catechol-O-methyltransferase (COMT) inhibitor that is approved for the treatment of Parkinson's disease (PD) associated with L-DOPA/L-amino acid decarboxylase inhibitor (DDI) therapy allowing for prolonged activity due to a more continuous supply of L-DOPA in the brain. Thus, OPC decreases fluctuation in L-DOPA plasma levels and favors more constant central dopaminergic receptor stimulation, thus improving PD symptomatology. AREAS COVERED: This review evaluates the preclinical development, pharmacology, pharmacokinetics and safety profile of OPC. Data was extracted from published preclinical and clinical studies published on PUBMED and SCOPUS (Search period: 2000-2019). Clinical and post-marketing data are also evaluated. EXPERT OPINION: OPC is a third generation COMT inhibitor with a novel structure. It has an efficacy and tolerability superior to its predecessors, tolcapone (TOL) and entacapone (ENT). It also provides a safe and simplified drug regimen that allows neurologists to individually adjust the existing daily administration of L-DOPA. OPC is indicated as an adjunctive therapy to L-DOPA/DDI in patients with PD and end-of-dose motor fluctuations who cannot be stabilized on those combinations.

Central nervous system activities of extract Mangifera indica L.

ETHNOBOTANICAL RELEVANCE: Leaves of Mangifera indica L. have folk-uses in tropical regions of the world as health teas, as a remedy for exhaustion and fatigue, as a vegetable, and as a medicine. Mangifera indica leaf extract (MLE) had previously been demonstrated to alter brain electrical activity in-vivo. The aim of the present series of studies was to investigate whether mangiferin, a major compound in leaves and in MLE, is responsible for the neurocognitive activity of MLE, and if the CNS activities of MLE have translational potential. MATERIALS AND METHODS: MLE, tradename Zynamite, is produced by Nektium Pharma, Spain. Isolated mangiferin was tested in-vitro in radioligand binding and enzyme inhibition studies against 106 CNS targets. Changes in the electroencephalograms (EEG's) of MLE and mangiferin were recorded in-vivo from four brain regions. Two double blind randomized placebo-controlled crossover clinical trials were conducted, each with 16 subjects. At 90 min and at 60 min respectively, after oral intake of 500 mg MLE, EEG recordings, psychometric tests, mood state, and tolerability were studied. RESULTS: Isolated mangiferin is a selective inhibitor of catechol-O-methyltransferase (COMT) with an IC50 of 1.1 µM, with no activity on the CNS targets of caffeine. Both mangiferin and MLE induce similar changes in long-term potentiation (LTP) in the hippocampus in-vitro, and induce a similar pattern of EEG changes in-vivo. In both translational clinical trials MLE was well tolerated, with no cardiovascular side-effects. In both studies MLE caused significant spectral changes in brain electrical activity in cortical regions during cognitive challenges, different to the attenuated spectral changes induced by caffeine. There were no significant changes in the psychometric tests other than reaction time for all groups. In the second study there was a trend to faster reaction time within group for MLE (p = 0.066) and the percentage improvement in reaction time for MLE compared to placebo was significant (p = 0.049). In the first study MLE improved all scores for Profile of Mood States (POMS), with the score for "fatigue" significantly improved (p = 0.015); in the second study the POMS score for "dejection" was improved in the caffeine group, p = 0.05. CONCLUSIONS: Mangiferin is a COMT inhibitor of moderate potency and is the major CNS-active compound in MLE. Both mangiferin and MLE increase hippocampal LTP in-vitro, and induce a similar pattern of changes in brain electrical activity in-vivo. While the translational clinical trials of MLE are limited by being single dose studies in a small number of subjects, they provide the first clinical evidence that the extract is well tolerated with no cardiovascular side-effects, can induce changes in brain electrical activity, may give a faster reaction time, and decrease fatigue. These CNS activities support the reported folk-uses use of mango leaf tea as a substitute for tea and as a traditional remedy for fatigue and exhaustion. Extract Mangifera indica L., Zynamite, has nootropic potential, and larger clinical studies are needed to realise this potential.

Pharmacokinetics and pharmacodynamics of levodopa/carbidopa cotherapies for Parkinson's disease.

Introduction: Parkinson's disease is a chronic, neurodegenerative disease entity with heterogeneous features and course. Levodopa is the most efficacious dopamine substituting drug. Particularly, long-term application of oral levodopa/decarboxylase inhibitor formulations sooner or later supports onset of fluctuations of movement. It also shifts levodopa turnover to O-methylation, which impairs human methylation capacity and increases oxidative stress.Areas covered: This narrative review summarizes pharmacokinetic and pharmacodynamic features of available levodopa cotherapies on the basis of a literature search with the terms L-dopa, inhibitors of catechol-O-methyltransferase and monoamine oxidase-B.Expert opinion: Long-term levodopa/dopa decarboxylase inhibitor application with concomitant inhibition of both, catechol-O-methyltransferase and monoamine oxidase-B supports a more continuous dopamine substitution, which ameliorates fluctuations of motor behavior. This triple combination also enhances both, antioxidative defense and methylation capacity. Inhibition of monoamine oxidase-B reduces generation of oxidative stress in the brain. Constraint of catechol-O-methyltransferase reduces homocysteine synthesis due to diminished consumption of methyl groups for levodopa turnover at least in the periphery. An additional nutritional supplementation with methyl group donating and free radical scavenging vitamins is recommendable, when future drugs are developed for long-term levodopa/dopa decarboxylase treated patients. Personalized medicine treatment concepts shall also consider nutritional aspects of Parkinson's disease.

Effects of Dopaminergic Drugs on Cognitive Control Processes Vary by Genotype.

Dopamine (DA) has been implicated in modulating multiple cognitive control processes, including the robust maintenance of task sets and memoranda in the face of distractors (cognitive stability) and, conversely, the ability to switch task sets or update the contents of working memory when it is advantageous to do so (cognitive flexibility). In humans, the limited specificity of available pharmacological probes has posed a challenge for understanding the mechanisms by which DA, acting on multiple receptor families across the PFC and striatum, differentially influences these cognitive processes. Using a within-subject, placebo-controlled design, we contrasted the impact of two mechanistically distinct DA drugs, tolcapone (an inhibitor of catechol-O-methyltransferase [COMT], a catecholamine inactivator) and bromocriptine (a DA agonist with preferential affinity for the D2 receptor), on the maintenance and switching of task rules. Given previous work demonstrating that drug effects on behavior are dependent on baseline DA tone, participants were stratified according to genetic polymorphisms associated with cortical (COMT Val158Met) and striatal (Taq1A) DA system function. Our results were partially consistent with an inverted-U-shaped relationship between tolcapone and robust rule maintenance (interaction with COMT genotype) and between bromocriptine and cued rule switching (interaction with Taq1A genotype). However, when task instructions were ambiguous, a third relationship emerged to explain drug effects on spontaneous task switching (interaction of COMT genotype and bromocriptine). Together, this pattern of results suggests that the effects of DA drugs vary not only as a function of the DA system component upon which they act but also on subtle differences in task demands and context.

Highs and lows of cannabinoid-dopamine interactions: effects of genetic variability and pharmacological modulation of catechol-O-methyl transferase on the acute response to delta-9-tetrahydrocannabinol in humans.

RATIONALE: The catechol-O-methyl transferase (COMT) enzyme has been implicated in determining dopaminergic tone and the effects of delta-9-tetrahydrocannabinol (THC) in the human brain. OBJECTIVE: This study was designed to evaluate the effect of (1) a functional polymorphism and (2) acute pharmacological inhibition of COMT on the acute response to THC in humans. METHODS: Sub-study I: The effect of intravenous (IV) THC (0.05 mg/kg) was investigated in 74 healthy subjects genotyped for the COMT rs4680 (Val/Met) polymorphism in a 2-test-day double-blind, randomized, placebo-controlled study. Sub-study II: COMT rs4680 homozygous subjects (Val/Val and Met/Met) from sub-study I received the COMT enzyme inhibitor tolcapone (200 mg) followed by IV THC or placebo on two additional test days. Subjective, behavioral, and cognitive data were obtained periodically on each test day. RESULTS: Sub-study I: Val/Val individuals were most sensitive to THC-induced attention and working memory deficits. In contrast, the psychotomimetic and subjective effects of THC were not influenced by COMT genotype. Sub-study II: Tolcapone reduced THC-induced working memory deficits, but not THC's psychotomimetic effects. Tolcapone and COMT genotype (met/met) were associated with an increased report of feeling "mellow." CONCLUSIONS: The interaction between COMT rs4680 polymorphisms and tolcapone on the cognitive, but not on the psychotomimetic and overall subjective effects of THC, suggests that modulation of dopaminergic signaling may selectively influence specific cannabinoid effects in healthy individuals. The role of dopaminergic signaling in the cognitive effects of cannabinoids should be considered in drug development efforts targeting these effects. CLINICALTRIALS.GOV REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT00678730?term=NCT00678730&rank=1 ClinicalTrials.gov Identifier: NCT00678730.

A novel electrochemical nanosensor based on NH2-functionalized multi walled carbon nanotubes for the determination of catechol-orto-methyltransferase inhibitor entacapone.

In this study, an antiparkinson drug Entacapone (ENP) is electrochemically investigated under optimized conditions using NH2 functionalized multi walled carbon nanotubes (NH2fMWCNT) decorated over glassy carbon electrode (GCE). The surface morphology of the NH2fMWCNT/GCE was probed by scanning electron microscopy (SEM) armed with EDX analysis. Electrochemical impedance spectroscopy (EIS) was employed to investigate the electron transfer capability of modified and bare electrodes. Cyclic voltammetry was used to compare the redox response of ENP on the surface of modified and unmodified electrodes. The influence of interfering agents was also studied to examine the selectivity of the designed sensor. For the purpose of practical applicability of the proposed method, differential pulse voltammetric method was applied for the investigation of ENP in real samples i.e., tablet, human serum and urine. Almost 100% recovery percentages were obtained from tablet, serum and urine samples with RSD% values of less than 2% for all the samples, thus, suggesting promising applicability of the designed electrochemical sensing platform (NH2fMWCNT/GCE) for determination of ENP in pharmaceutical dosage and real samples.

Inhibition of catechol-O-methyltransferase in the cynomolgus monkey by opicapone after acute and repeated administration.

INTRODUCTION: The aim of the study was to clarify the dose response for inhibition of catechol-O-methyltransferase (COMT) by opicapone, a third generation COMT inhibitor, after acute and repeated administration to the cynomolgus monkey with pharmacokinetic evaluation at the higher dose. METHODS: Three cynomolgus monkeys were used in the study. In the first experiment, COMT inhibition was evaluated over 24 h after the first and at 24 h after the last of 14 daily oral administrations of vehicle, 1, 10 and 100 mg/kg opicapone using a crossover design. In the second experiment, the effect of the maximally effective dose, 100 mg/kg, was retested under the same conditions with additional monitoring of plasma opicapone levels to explore the relationship between pharmacokinetics and pharmacodynamics. RESULTS: Opicapone dose-dependently inhibited COMT activity, significantly so at 10 and 100 mg/kg. Maximal inhibition was 13.1%, 76.4% and 93.2% at 1, 10 and 100 mg/kg respectively, and COMT remained significantly inhibited at 24 h after 10 and 100 mg/kg (42.6% and 60.2% respectively). Following repeated administration of opicapone residual COMT inhibition at 24 h was 15-25% greater at all doses. In contrast to its pharmacodynamic effect, opicapone was rapidly absorbed and eliminated, with no accumulation in plasma following repeated administration. CONCLUSION: Opicapone showed sustained and dose-dependent COMT inhibition despite being rapidly eliminated from plasma and with no evidence for accumulation in plasma after 14 days administration. Opicapone fills the unmet need for a compound with sustained COMT inhibition which will improve levodopa bioavailability in patients with Parkinson's disease.

The launch of opicapone for Parkinson's disease: negatives versus positives.

INTRODUCTION: Opicapone is a novel, third generation COMT inhibitor approved for the treatment of Parkinson's disease. Safety and tolerability data is critical to determine the benefit-harm balance and anticipate therapeutic adherence. Areas covered: This review evaluates the tolerability and safety profile of opicapone. These data were extracted from all published clinical trials, including preclinical, phase I, phase II and phase III studies as well as postmarketing data. Opicapone was safe and well tolerated, with frequencies of treatment-emergent adverse events similar to placebo. Expert opinion: Opicapone have shown a good safety and tolerability profile. This adds to its proven efficacy and convenient once-daily administration, supporting a role of opicapone as a first-line therapy for motor complications in Parkinson's disease patients.

Pharmacokinetic drug evaluation of opicapone for the treatment of Parkinson's disease.

INTRODUCTION: Opicapone (OPC) is a novel, potent, reversible, and purely peripheral third-generation COMT inhibitor, which provides an enhancement in levodopa (L-Dopa) availability. It represents adjunctive therapy for L-Dopa treated patients with PD and motor fluctuations. Areas covered: The purpose of this study was to evaluate pharmacokinetic of OPC for the treatment of PD. Expert commentary: Oral OPC exhibits linear, dose-dependent absorption. However, following concomitant ingestion of a high-fat, high-calorie meal, the maximum plasma concentration will be decreased. A once-daily bedtime administration of OPC 1 h after the last daily L-Dopa/AADCi, are considered to avoid any interaction during the L-Dopa absorption phase. There are no clinically relevant effects of age (in adults), renal impairment or race on the pharmacokinetics of OPC. OPC dose adjustment is not needed in patients with mild to moderate chronic hepatic impairment. Opicapone exhibits the lowest potential for cytotoxicity in comparison with other COMT inhibitors. It significantly decreases COMT activity, with half-life of COMT inhibition in human erythrocytes of 61.6 h and increases systemic exposure to L-Dopa. This provides an enhancement in L-Dopa availability that translates into clinical benefit for PD patients in terms of significant decrease of OFF periods and increase in ON-time without troublesome dyskinesia.

The Risk Factors for the Wearing-off Phenomenon in Parkinson's Disease in Japan: A Cross-sectional, Multicenter Study.

Objective Parkinson's disease (PD) is a common, progressive, neurodegenerative disorder. With progression of PD, the wearing-off phenomenon occurs more frequently as a motor complication, decreasing the patient's quality of life. The aim of this study was to investigate the risk factors for the wearing-off phenomenon in Japanese PD patients. Methods All of the study participants were clinically diagnosed as having PD. Each patient was assessed for the wearing-off phenomenon based on the findings of clinical assessments and interviews that were conducted during a single visit. The risk factors for wearing-off were analyzed by univariate and multivariate logistic regression analyses. Results Wearing-off was observed in 101 of the 180 (56.1%) patients who were enrolled in this study. The multivariate logistic regression analysis revealed that the onset of PD at ≥69 years of age (odds ratio [OR], 0.22; 95% confidence interval [CI], 0.05-0.88; p=0.032), female sex (OR, 6.49; 95% CI, 2.34-17.99; p<0.001), catechol-O-methyltransferase (COMT) inhibitor treatment (OR, 19.59; 95% CI, 3.55-108.11; p<0.001) and a high daily levodopa dosage (≥600 mg/day) (OR, 7.69; 95% CI, 1.41-41.84; p=0.018) were independent predictive factors for wearing-off in Japanese PD patients. Conclusion Age at the symptomatic disease onset, female sex, COMT inhibitor treatment, and a high daily levodopa dose were associated with the occurrence of wearing-off in Japanese PD patients. Physicians need to consider the risk factors and carefully choose medications for PD patients to postpone the occurrence of this phenomenon for as long as possible.