A Double‐Blind,Randomized, Placebo and Active‐Controlled Study of Nebicapone for the Treatment of Motor Fluctuations in Parkinson's Disease

To determine the efficacy, safety and tolerability of nebicapone, a new catechol‐O‐methyltransferase inhibitor for the treatment of motor fluctuations in Parkinson's disease (PD), we conducted a multicenter, randomized, 8‐week double‐blind, placebo‐ and active‐controlled, parallel‐group study comparing nebicapone 50 mg, 100 mg, or 150 mg, entacapone 200 mg (active control) or placebo administered concomitantly with levodopa/carbidopa or levodopa/benserazide. Two hundred and fifty‐two PD patients with motor fluctuations treated with levodopa/carbidopa or levodopa/benserazide (4–8 daily doses) were enrolled and 250 patients were eligible for intention‐to‐treat (ITT) analysis on the basis of having at least one efficacy assessment. The primary endpoint was 8‐week change from baseline in absolute “Off” time duration noted in self‐scoring diaries. At 8 weeks of treatment the mean daily “Off” time decreased significantly compared to placebo for nebicapone 150 mg (?106 min; 95%CI: ?192; ?21) and entacapone 200 mg (?81 min; 95%CI: ?142; ?19). The decrease in “Off” time with nebicapone 50 mg or 100 mg did not reach statistical significance. Treatment‐emergent adverse events were reported by 32% to 49% of patients in any treatment group, with no observed dose relationship in the nebicapone groups. Clinically relevant elevations in aspartate transaminase (AST) and/or alanine transaminase (ALT) were observed in 4 of 46 patients with the nebicapone 150 mg dose. The results of this study show that nebicapone 150 mg is efficacious for the treatment of motor fluctuations in PD patients. However, the risk of increasing liver transaminases and its clinically relevance deserves further evaluation.     

Early versus delayed initiation of entacapone in levodopa‐treated patients with Parkinson’s disease: a long‐term,retrospective analysis

Background: We analysed data from three clinical trials in Parkinson’s disease (PD) patients with wearing‐off to determine whether early enhancement of levodopa therapy with entacapone can lead to better long‐term outcomes than delayed entacapone treatment. Methods: Post‐hoc analysis of pooled data from three randomized, double‐blind, placebo‐controlled studies and their long‐term, open‐label extension phases. In all three studies, patients on levodopa/dopa‐decarboxylase inhibitor (DDCI) were first randomized to entacapone (‘early‐start’ group) or placebo (‘delayed‐start’ group) for the initial 6‐month double‐blind phase, after which all patients received open‐label levodopa/DDCI and entacapone treatment for up to 5 years. Results: A total of 488 PD patients with wearing‐off were included in the analysis. A statistically significant benefit of early initiation of levodopa/DDCI and entacapone was found, with an improvement in Unified Parkinson’s Disease Rating Scale Part III (motor) score of ?1.66 (95% confidence intervals [?3.01, ?0.31]) points compared with the delayed‐start treatment group (P < 0.05). Levodopa/DDCI and entacapone therapy was well tolerated. There was no excess of dyskinesia in the early‐start group. Conclusions: These data suggest that early rather than delayed addition of entacapone to levodopa/DDCI in PD patients with wearing‐off provides a modest clinical benefit over levodopa/DDCI that is maintained for up to 5 years.     

The effect of peripheral enzyme inhibitors on levodopa concentrations in blood and CSF

Levodopa combined with a dopa‐decarboxylase inhibitor, such as carbidopa, shifts the metabolism to the COMT pathway. Adding the peripheral acting COMT inhibitor entacapone provides improvement for patients with PD suffering from motor fluctuations. We studied the effects of the enzyme inhibitors entacapone and carbidopa on the levodopa concentrations in CSF and in blood. Five PD patients with wearing‐off underwent lumbar drainage and intravenous microdialysis. Samples were taken 12 h daily for 3 days. Day 1; intravenous levodopa was given, day 2; additional oral entacapone 200 mg tid, day 3; additional oral entacapone 200 mg tid and carbidopa 25 mg bid. Levodopa in CSF and in dialysates was analysed. The AUC for levodopa increased both in blood and CSF when additional entacapone was given alone and in combination with carbidopa. The C_max of levodopa in both CSF and blood increased significantly. Additional entacapone to levodopa therapy gives an increase of C_max in CSF and in blood. The increase is more evident when entacapone is combined with carbidopa. © 2010 Movement Disorder Society     

Randomized trial of safinamide add‐on to levodopa in Parkinson's disease with motor fluctuations

Levodopa is effective for the motor symptoms of Parkinson's disease (PD), but is associated with motor fluctuations and dyskinesia. Many patients require add‐on therapy to improve motor fluctuations without exacerbating dyskinesia. The objective of this Phase III, multicenter, double‐blind, placebo‐controlled, parallel‐group study was to evaluate the efficacy and safety of safinamide, an α‐aminoamide with dopaminergic and nondopaminergic mechanisms, as add‐on to l ‐dopa in the treatment of patients with PD and motor fluctuations. Patients were randomized to oral safinamide 100 mg/day (n = 224), 50 mg/day (n = 223), or placebo (n = 222) for 24 weeks. The primary endpoint was total on time with no or nontroublesome dyskinesia (assessed using the Hauser patient diaries). Secondary endpoints included off time, Unified Parkinson's Disease Rating Scale (UPDRS) Part III (motor) scores, and Clinical Global Impression‐Change (CGI‐C). At week 24, mean ± SD increases in total on time with no or nontroublesome dyskinesia were 1.36 ± 2.625 hours for safinamide 100 mg/day, 1.37 ± 2.745 hours for safinamide 50 mg/day, and 0.97 ± 2.375 hours for placebo. Least squares means differences in both safinamide groups were significantly higher versus placebo. Improvements in off time, UPDRS Part III, and CGI‐C were significantly greater in both safinamide groups versus placebo. There were no significant between‐group differences for incidences of treatment‐emergent adverse events (TEAEs) or TEAEs leading to discontinuation. The addition of safinamide 50 mg/day or 100 mg/day to l ‐dopa in patients with PD and motor fluctuations significantly increased total on time with no or nontroublesome dyskinesia, decreased off time, and improved parkinsonism, indicating that safinamide improves motor symptoms and parkinsonism without worsening dyskinesia. © 2013 International Parkinson and Movement Disorder Society     

Effect of rasagiline as adjunct therapy to levodopa on severity of OFF in Parkinson's disease

Background: The LARGO study demonstrated that rasagiline 1 mg/day as adjunct to levodopa significantly reduces OFF time to the same magnitude as adjunct entacapone. This substudy of LARGO aimed to assess the effect of rasagiline and entacapone on the motor symptoms of PD during the practically defined OFF state. Methods: LARGO was a randomized, double‐blind, multicenter trial that assessed the efficacy and safety of rasagiline (1 mg/day), entacapone (200 mg with each levodopa dose), and placebo in 687 levodopa‐treated PD patients with motor fluctuations. A substudy of LARGO measured UPDRS motor scores in the practically defined OFF state in 32 rasagiline, 36 entacapone, and 37 placebo patients. Results: Treatment with rasagiline produced a significant improvement over placebo of 5.64 units in UPDRS motor OFF score (P = 0.013 vs. placebo). By contrast, the effect of adjunct entacapone was not significant (P = 0.14 vs. placebo). Whereas rasagiline also showed a trend in reducing the UPDRS‐ADL OFF score (P = 0.058 vs. placebo), no such trend was noted for entacapone (P = 0.26 vs. placebo). Retrospective analysis, using the Bonferroni correction, of UPDRS motor subdomains further revealed that rasagiline, but not entacapone, significantly improved bradykinesia (P < 0.001) and showed trends for improvements in facial expression, speech, and axial impairment during OFF time. Conclusions: This study provides the first objectively measured evidence that adjunct rasagiline 1 mg/day is effective in reducing the severity of motor symptoms in the OFF state. This suggests a continuous effect of rasagiline 1 mg/day throughout the day and night and is consistent with its extended duration of therapeutic action.     

Entacapone to tolcapone switch: Multicenter double‐blind,randomized, active‐controlled trial in advanced Parkinson's disease

This double‐blind study examined the efficacy and safety of replacing entacapone with tolcapone in fluctuating Parkinson's disease (PD) patients. Patients receiving entacapone for ≥15 days were randomly assigned to continue entacapone (n = 75) or switch to tolcapone (n = 75) and were followed up for 3 weeks. Efficacy measures included changes in on time (without disabling dyskinesia) and an investigator's global assessment (IGA). The on time increased by ≥1 hour/day (primary efficacy measure) in 43% of entacapone‐treated patients and 53% of tolcapone‐treated patients, and by ≥3 hours/day in 13% and 25%, respectively. The IGA indicated moderate/marked improvements in 25% of entacapone patients and 39% receiving tolcapone. Response rates (the proportion of patients with ≥1 hour/day increase in on time and improvements on IGA) were 17% with entacapone and 32% with tolcapone. Dyskinesia was the most common adverse event affecting 29% of entacapone and 31% of tolcapone recipients. One patient in each group had elevated liver enzymes, resulting in treatment withdrawal (levels returned to normal thereafter in both cases). In conclusion, within the limits of the protocol, there was a tendency for tolcapone to offer enhanced efficacy in patients with fluctuating PD, despite optimized entacapone therapy. Tolcapone can be considered, therefore, for patients whose motor fluctuations are inadequately controlled by their existing regimen. © 2006 Movement Disorder Society     

Quality of life in early Parkinson's disease treated with levodopa/carbidopa/entacapone

We aimed to investigate whether treatment with levodopa/carbidopa/entacapone when compared with levodopa/carbidopa improves quality of life in Parkinson's disease (PD) patients with no or minimal, nondisabling motor fluctuations. This is a multicenter, randomized, double‐blind study. One hundred eighty‐four patients on 3 to 4 equal doses of 100/25 to 200/50 mg levodopa/carbidopa or levodopa/benserazide, 0 to 3 hours of nondisabling OFF time over a 48 hour period and no dyskinesia were randomized to levodopa/carbidopa/entacapone or levodopa/carbidopa treatment for 12 weeks. The primary outcome measure was quality of life as assessed by the PDQ‐8. Secondary outcome measures were the UPDRS parts I–IV, and the Wearing Off Card. Treatment with levodopa/carbidopa/entacapone resulted in significantly greater improvements in PDQ‐8 scores compared to treatment with levodopa/carbidopa (mean difference 1.4 points, P = 0.021). Statistically significant improvements were seen predominantly in nonmotor domains (depression, personal relationships, communication, stigma, all P < 0.05; dressing P = 0.056). Patients who were randomly assigned to levodopa/carbidopa/entacapone also showed significantly greater improvement in UPDRS part II scores (P = 0.032) with UPDRS part III scores showing borderline significance. Differences in UPDRS parts I and IV and Wearing Off Card scores were not significant. Treatment with levodopa/carbidopa/entacapone results in improved quality of life compared with levodopa/carbidopa in PD patients with mild or minimal, nondisabling motor fluctuations. © 2007 Movement Disorder Society     

Efficacy and safety of entacapone in Parkinson's disease patients with suboptimal levodopa response: a 6-month randomized placebo-controlled double-blind study in Germany and Austria (Celomen study)

OBJECTIVES: To determine the efficacy and safety of the catechol-O-methyltransferase (COMT) inhibitor entacapone, used as an adjunct to levodopa, in Parkinson's disease (PD) patients. PATIENTS AND METHODS: In this parallel group, randomized, double-blind study, 301 PD patients, the majority with motor fluctuations, received entacapone (200 mg) or placebo with each daily dose of standard or controlled-release (CR) levodopa. The 24-week treatment period was followed by 2 weeks of entacapone withdrawal. Efficacy was determined by home diaries ('on' and 'off' times), Unified Parkinson's Disease Rating Scale (UPDRS) and changes in levodopa dosage, and safety by adverse-event inquiry, vital signs, electro cardiography (ECG) and laboratory tests. RESULTS: In the total population, the UPDRS activities of daily living and motor scores were significantly improved (P < 0.05) by entacapone vs placebo. In fluctuating patients, 'on' time increased (1.7 h) and 'off' time decreased (1.5 h) significantly more with entacapone than with placebo (0.5 and 0.6 h, respectively; P < 0.05), and the daily levodopa dose was reduced by 54 mg with entacapone and increased by 27 mg with placebo (P < 0.05). Entacapone benefit was lost on withdrawal. Entacapone efficacy was comparable between patients using CR and standard levodopa preparations. Increased dyskinesias (entacapone 34%, placebo 26%) and nausea (10 and 5%, respectively), mostly occurring shortly after treatment initiation, were generally managed by reducing the levodopa dose. Diarrhoea (entacapone 8%, placebo 4%) was seldom severe. There were no differences in vital signs, ECG or laboratory results. CONCLUSION: Entacapone is an effective and safe levodopa extender and enhancer, improving the symptomatic efficacy of levodopa in PD and adding to the patients' benefit.     

Clinical efficacy of istradefylline (KW‐6002) in Parkinson's disease: A randomized,controlled study

The objectives of this study were to evaluate the efficacy of istradefylline at an oral dose of 20 mg or 40 mg once daily for 12 weeks in Parkinson's disease (PD) patients with motor complications on levodopa therapy based on the change in the daily OFF time compared with placebo and to assess the safety at these doses. A total of 363 subjects were randomly assigned to receive 20 mg/day istradefylline (n = 119), 40 mg/day istradefylline (n = 125), or placebo (n = 119). The primary outcome variable was the change from baseline at endpoint in daily OFF time based on patients' ON/OFF diaries. At endpoint, the daily OFF time reduced from baseline by 1.31 hours for 20 mg/day istradefylline (P = 0.013 as compared to the placebo), 1.58 hours for 40 mg/day istradefylline (P < 0.001), and 0.66 hours for placebo; istradefylline significantly reduced the daily OFF time compared with placebo. The UPDRS Part III subscale score (ON state) reduced by 5.7 at endpoint in both istradefylline groups and 3.7 in the placebo group (P = 0.006 for 20 mg/day and P = 0.006 for 40 mg/day group as compared with placebo). The most commonly reported drug‐related treatment emergent adverse event (TEAE) was dyskinesia, which occurred in 2.5% (3/119) of subjects receiving placebo, 8.5% (10/118) receiving 20 mg/day istradefylline, and 6.4% (8/125) receiving 40 mg/day istradefylline. We conclude that istradefylline at 20 mg and 40 mg once daily is effective in relieving wearing‐off fluctuations of PD patients. In addition, istradefylline was well tolerated at both doses. © 2010 Movement Disorder Society     

Entacapone improves motor fluctuations in levodopa- treated Parkinson's disease patients

Motor fluctuations associated with levodopa therapy are common problems encountered in the long-term treatment of Parkinson's disease (PD). Entacapone, a peripherally acting, reversible inhibitor of catechol-O-methyltransferase, slows the elimination of levodopa in humans by reducing the formation of 3-O-methyldopa. We conducted a placebo-controlled, double-blind, parallel-group, multicenter trial of entacapone in PD patients with motor fluctuations. Two hundred five patients were randomized to receive either entacapone 200 mg or matching placebo with each dose of levodopa and were followed for 24 weeks. The primary measure of efficacy was the change in percentage of “on” time (relief of parkinsonism) while awake, as recorded by subjects at home in diaries completed at 30-minute intervals. At baseline, patients averaged approximately 10 hours of “on” time per day while awake (60.5% “on” time), and entacapone treatment increased the percent “on” time by 5.0 percentage points. The effect of entacapone was more prominent in patients with a smaller percent “on” time (<55%) at baseline, and increased as the day wore on. Entacapone is effective at increasing the duration of response to levodopa and at relieving parkinsonism in patients experiencing motor flucturations and was well tolerated during the 24 weeks of treatment.     

Entacapone is beneficial in both fluctuating and non-fluctuating patients with Parkinson's disease: a randomised,placebo controlled,double blind,six month study

OBJECTIVE: To study the effect of entacapone, a specific peripherally acting catechol-O-methyltransferase (COMT) inhibitor used in combination with levodopa treatment, in cases of Parkinson's disease with both fluctuating and non-fluctuating response to treatment. METHODS: A randomised, placebo controlled, double blind, six month study was undertaken in 172 fluctuating and 128 non-fluctuating patients. The clinical efficacy and safety of 200 mg entacapone given with each daily levodopa dose was studied. Efficacy was examined using home diaries, the unified Parkinson disease rating scale (UPDRS), and recording of daily levodopa dose. RESULTS: The primary efficacy variable for fluctuating patients-the proportion of daily ON time-showed a significant increase compared with placebo (p < 0.05). The absolute ON time (mean (SD)) increased from 9.5 (2.5) to 10.8 (2.4) hours (p < 0.01), and the daily OFF time was correspondingly reduced from 7.0 (2.6) to 5.9 (2.5) hours (p < 0.05 v placebo). This improvement was achieved despite a reduction in daily levodopa requirements. The effect was rapidly lost on withdrawal of entacapone. In non-fluctuating patients, the primary efficacy measure was part II of the UPDRS (activities of daily living; ADL). In this group of patients, ADL scores improved in the entacapone group (p < 0.01 v placebo), and there was also a 40 mg reduction in levodopa requirement (p < 0.01 v placebo). Entacapone was well tolerated by both fluctuating and non-fluctuating patients. CONCLUSIONS: The ability of entacapone to provide additional benefits to levodopa treatment in increasing ON time in fluctuating Parkinson's disease patients was confirmed. A novel finding was that patients without fluctuations also obtained benefit from the addition of entacapone to their levodopa treatment, as evidenced by improved ADL scores and a relatively reduced levodopa requirement.     

Twelve-month safety of entacapone in patients with Parkinson's disease

The safety of entacapone combined with levodopa and a dopadecarboxylase (DDC) inhibitor was tested in a 12-month double-blind study of 326 patients with idiopathic Parkinson's disease (PD). The study population represented 'typical' PD outpatients, including patients with varying disease severity and with various concomitant medications. Two-thirds of the patients were randomized to receive 200 mg of entacapone with each of 2--10 daily levodopa doses, and one-third to receive placebo. All entacapone patients were included in the safety evaluation of adverse events (AEs), vital signs, ECG, and laboratory parameters. Entacapone was well tolerated with a discontinuation rate due to AEs of 14% compared with 11% with placebo (NS). As expected, due to dopaminergic enhancement, dyskinesia was more frequent as an AE with entacapone than with placebo. Dryness of mouth, urine discoloration and diarrhoea were more frequent non-dopaminergic AEs with entacapone than with placebo. Entacapone had no adverse effects on hepatic enzyme activity, ECG or haemodynamic parameters, and there was no evidence of any toxicity. As an indication of levodopa enhancement with entacapone, patients taking 5--10 doses of levodopa, most likely representing predominantly fluctuating patients, showed a significant decrease in their mean daily levodopa dose of 94 mg in the entacapone group compared with a decrease of 39 mg in the placebo group (P < 0.01). The interval between the first two morning doses of levodopa increased by 17% with entacapone, whereas with placebo no extension was observed (P < 0.05). Despite levodopa dose reduction, efficacy of entacapone was maintained. As further evidence of efficacy, Parkinsonian symptoms markedly worsened in all patients after withdrawal of entacapone. We conclude that entacapone is safe in optimizing levodopa in long-term treatment of idiopathic Parkinson's disease. Monitoring of liver or other safety parameters during entacapone treatment is not required.     

Entacapone improves the pharmacokinetic and therapeutic response of controlled release levodopa/carbidopa in Parkinson’s patients

Summary. The aim of this trial was to evaluate the effects of the COMT inhibitor entacapone on both the pharmacokinetic profile and clinical efficacy of controlled release levodopa in Parkinsons disease (PD) patients. Twelve PD patients experiencing end-of-dose type motor fluctuations were evaluated in this single-blind, randomized cross-over study. A single dose of either entacapone (200mg) or placebo was co-administered with controlled release levodopa. Blood samples were taken every 30 minutes for 3 hours, and in 6 patients, sampling was continued for a further 3 hours. The clinical response to treatment was evaluated using the Unified Parkinsons Disease Rating Scale motor score. Addition of entacapone to levodopa treatment prolonged the on phase of the PD patients by 37% (p<0.05). This increased duration of on time was concomitant with a significant increase in levodopa bioavailability (AUC). These data confirm the ability of entacapone to enhance the clinical efficacy of controlled release levodopa formulations, and provide further evidence that entacapone is of value in extending the benefits of levodopa in PD patients experiencing motor fluctuations.     

The tolerability and efficacy of entacapone over 3 years in patients with Parkinson''s disease

The long-term safety and efficacy of the catechol-O-methyltransferase (COMT) inhibitor entacapone was investigated in a 3-year open-label extension of the 6-month double-blind placebo-controlled Nordic (NOMECOMT) study. After a wash-out following this study, 132 patients with Parkinson's disease (PD) experiencing motor fluctuations treated with levodopa/dopa decarboxylase (DDC) inhibitor received additional therapy with entacapone 200 mg, administered with each dose of levodopa. The most common adverse events (AEs) were insomnia (30%), dizziness (20%), nausea (20%), aggravated parkinsonism (17%) and hallucinations (14%). Only 19 (14%) patients discontinued because of AEs. Most dopaminergic AEs occurred shortly after initiation of entacapone, and these could be managed by levodopa down-adjustment. The mean duration of benefit of a single dose of levodopa increased significantly from 2.1 to 2.8 h (P < 0.01) at 3 months and remained prolonged for the whole study. At the end of the study, the mean daily dose of levodopa was significantly decreased from baseline (from 737 to 696 mg; P < 0.05). The patients' global assessment indicated that 69% of patients improved when given entacapone and this proportion was maintained until the end of the study (64%). There was a significant worsening of disability upon withdrawal of entacapone. In conclusion, entacapone given in combination with levodopa, has a good long-term safety profile and a sustained beneficial effect in patients with PD with motor fluctuations.     

Study of istradefylline in patients with Parkinson's disease on levodopa with motor fluctuations

The objective of this study was to evaluate the efficacy, safety, and tolerability of istradefylline 20 mg once daily versus placebo as an adjunct to levodopa in subjects with Parkinson's disease (PD) who have motor fluctuations. Istradefylline (KW‐6002) is an adenosine A_2A receptor antagonist that in primate models of PD improves motor function without causing or worsening dyskinesia. This 12‐week, multicenter, double‐blind, placebo‐controlled, randomized, Phase 3 study of istradefylline was conducted in subjects experiencing an average daily OFF time of at least 3 hours (116 randomized to istradefylline; 115 to placebo). All were on stable levodopa regimens; 90% were also on stable regimens of other anti‐Parkinson's medications. Istradefylline‐treated subjects had significant placebo‐corrected reductions in daily OFF time from baseline to endpoint: 4.6% (P = 0.03) and 0.7 hours (P = 0.03). For ON time with troublesome dyskinesia, the changes between istradefylline and placebo were not significant. Istradefylline was well tolerated, with 6 (5.2%) istradefylline‐treated and 7 (6.1%) placebo‐treated subjects withdrawing from the study because of adverse events. Dyskinesia, lightheadedness, tremor, constipation, and weight decrease were reported more often with istradefylline than placebo. We conclude that istradefylline is well tolerated and significantly reduces OFF time as an adjunct to levodopa in PD subjects with motor fluctuations. © 2008 Movement Disorder Society     

COMT inhibition in the treatment of Parkinson’s disease

A new approach in the treatment of Parkinson’s disease is the inhibition of catechol-O-methyltransferase (COMT) with new generation COMT inhibitors, entacapone and tolcapone. Entacapone acts mainly peripherally whereas tolcapone acts both peripherally and centrally. They induce a dose-dependent inhibition of COMT activity in erythrocytes and a significant decrease in the plasma levels of 3-O-methyldopa, indicating their effectiveness as COMT inhibitors. Consequently, they increase the elimination half-life of levodopa and thus prolong the availability of levodopa to the brain without significantly affecting the C_max or t_max of levodopa. Clinically, the improved levodopa availability is seen as prolonged motor response to levodopa/DDC inhibitor and also as prolonged duration of dyskinesias in Parkinson’s disease patients with end-of-dose fluctuations. The dyskinesias are managed by decreasing the daily levodopa dose in Parkinson’s disease patients with end-of-dose fluctuations. Both pharmacokinetically and clinically the 200-mg dose of entacapone is the most effective dose compared with placebo. For tolcapone 100 and 200 mg have most often proved to be the optimal doses. Based on the duration of COMT inhibition entacapone is administered with each levodopa/DDC inhibitor dose whereas tolcapone is given three times daily. Both entacapone and tolcapone are well-tolerated. However, there seems to be a trend for tolcapone to induce more often diarrhoea and increase in liver transaminases compared with entacapone. Thus, COMT inhibitors are clinically significant and beneficial adjunct to levodopa therapy in Parkinson’s disease patients with end-of-dose fluctuations. Their effects and significance also in the treatment of de novo patients need to be clarified.

     

Efficacy and tolerability of entacapone in patients with Parkinson's disease treated with levodopa plus a dopamine agonist and experiencing wearing-off motor fluctuations. A randomized,double-blind,multicentre study

The efficacy and tolerability of entacapone was investigated in a randomized, double-blind, placebo-controlled, 3-month study of 162 patients with Parkinson's disease (PD) treated with levodopa and a dopamine agonist and experiencing wearing-off motor fluctuations. Patients were randomized in a 3 : 2 ratio to entacapone 200 mg or placebo, administered with each dose of levodopa. Efficacy was judged on the improvement of "on" and "off" time while awake (Patient Diary and UPDRS part IV Item 39), Investigators' Global Assessment, the SF-36 Health Survey, and changes in levodopa dosages. Patients were monitored for adverse events, laboratory safety and vital signs throughout the study. Improvements in "on" time as assessed using patient diary data showed a trend in favour of entacapone, however these did not reach statistical significance. "Off" time while awake (UPDRS part IV Item 39) showed an improvement of at least one category in 36% of entacapone-treated patients, compared with 22% in the control group (p = 0.0038). The proportion of patients showing an improvement at the Investigators' Global Assessment was significantly higher (p = 0.0006) in the entacapone-treated group of patients. Also, the proportion of patients with a reduction in their daily levodopa dose was significantly higher (p = 0.02) in the entacapone group (28%) compared with placebo (13%). As expected, the most frequent adverse events were dopamine-mediated (dyskinesia: entacapone 31% versus placebo 13%), and harmless urinary discoloration. The modest increase in dyskinesias could be readily managed by levodopa down-adjustment, and, at study end there was no significant difference for the UPDRS "overall dyskinesia score" between entacapone and placebo. In conclusion, although the primary efficacy variable did not reach statistical significance, the present results demonstrate that entacapone provides additional antiparkinsonian benefits to levodopa therapy and is well tolerated in levodopa-treated PD patients experiencing wearing-off motor fluctuations despite adjunct dopamine agonist therapy.     

Double‐blind trial of levodopa/carbidopa/entacapone versus levodopa/carbidopa in early Parkinson's disease

We performed a 39‐week, randomized, double‐blind, multicenter study to compare the efficacy, safety, and tolerability of levodopa/carbidopa/entacapone (LCE, Stalevo) with levodopa/carbidopa (LC, Sinemet IR) in patients with early Parkinson's disease (PD). Four hundred twenty‐three patients with early PD warranting levodopa were randomly assigned to treatment with LCE 100/25/200 or LC 100/25 three‐times daily. The adjusted mean difference in total Unified Parkinson's disease Rating Scale (UPDRS) Parts II and III between groups using the analysis of covariance model (prespecified primary outcome measure) was 1.7 (standard error = 0.84) points favoring LCE (P = 0.045). Significantly greater improvement with LCE compared with LC was also observed in UPDRS Part II activities of daily living (ADL) scores (P = 0.025), Schwab and England ADL scores (blinded rater, P = 0.003; subject, P = 0.006) and subject‐reported Clinical Global Impression (CGI) scores (P = 0.047). There was no significant difference in UPDRS Part III or investigator‐rated CGI scores. Wearing‐off was observed in 29 (13.9%) subjects in the LCE group and 43 (20.0%) in the LC group (P = 0.099). Dyskinesia was observed in 11 (5.3%) subjects in the LCE group and 16 (7.4%) in the LC group (P = 0.367). Nausea and diarrhea were reported more frequently in the LCE group. LCE provided greater symptomatic benefit than LC and did not increase motor complications. © 2008 Movement Disorder Society     

Catechol-O-methyltransferase inhibition with entacapone: Evidence from controlled clinical trials in Parkinson's disease

Adjunct therapy with the catechol-O-methyltransferase inhibitor entacapone is a first-line approach to treat wearing-off type motor fluctuations in levodopa-treated Parkinson's disease (PD) patients. Five randomized placebo-controlled trials including a total of >1000 patients have established its efficacy, showing increases in ON time between 0.7 and 1.6 h, with corresponding OFF-time reductions. These and other trials also found improvements in ON motor function and quality of life. Additional trials have tested the efficacy of adjunct entacapone in patients either without or with early and mild motor fluctuations and also found enhanced motor control and improved activities of daily living function and quality of life, whereas the STRIDE-PD trial failed to show efficacy of early entacapone use in delaying the onset of dyskinesias. Adjunct entacapone enhances dopaminergic activity and may increase levodopa-induced adverse events like dyskinesias, which can usually be controlled by modest levodopa dose reductions. There is no formal requirement to monitor liver function during entacapone treatment. Entacapone can be a rare cause of lymphocytic colitis with severe diarrhoea and need for treatment discontinuation. In 2003, a triple-combination pill of levodopa, carbidopa, and entacapone (LCE) was first introduced onto the market, and since then proprietary LCE (Stalevo^®) is indicated on the basis of those trials for patients with idiopathic PD to (i) substitute for immediate-release carbidopa/levodopa and entacapone previously administered as individual products or (ii) replace immediate-release carbidopa/levodopa therapy (without entacapone) when patients taking a total daily dose of levodopa of ≤600 mg and not experiencing dyskinesias experience signs and symptoms of end-of-dose wearing off.     

Trial of dextromethorphan/quinidine to treat levodopa‐induced dyskinesia in Parkinson's disease

Background : Nondopaminergic pathways represent potential targets to treat levodopa‐induced dyskinesia in Parkinson's disease (PD). This pilot‐study (NCT01767129) examined the safety/efficacy of the sigma‐1 receptor‐agonist and glutamatergic/monoaminergic modulator, dextromethorphan plus quinidine (to inhibit rapid dextromethorphan metabolism), for treating levodopa‐induced dyskinesia. Methods : PD patients were randomized to dextromethorphan/quinidine (45 mg/10 mg twice daily)/placebo in two 2‐week double‐blind, crossover treatment periods, with intervening 2‐week washout. After 14 days, a 2‐hour intravenous levodopa‐infusion was administered. Patient examinations were videotaped before infusion (“off” state) and every 30 minutes during and afterwards until patients returned to “off.” The primary endpoint was dyskinesia‐severity during infusion measured by Unified Dyskinesia Rating Scale part 3 area‐under‐curve scores (blinded expert rated). Additional endpoints included other dyskinesia/motor assessments, global measures of clinical‐change, and adverse‐events. Results : A total of 13 patients were randomized and completed the study (efficacy‐evaluable population). Dyskinesia‐severity was nonsignificantly lower with dextromethorphan/quinidine than placebo during infusion (area‐under‐curve 966.5 vs 1048.8; P = .191 [efficacy‐evaluable patients]), and significantly lower in a post‐hoc sensitivity analysis of the per‐protocol‐population (efficacy‐evaluable patients with ≥ 80% study‐drug‐compliance, n = 12) when measured from infusion start to 4‐hours post–infusion completion (area‐under‐curve 1585.0 vs 1911.3; P = .024). Mean peak dyskinesia decreased significantly from infusion‐start to return to “off” (13.3 vs 14.9; P = .018 [efficacy‐evaluable patients]). A total of 9 patients rated dyskinesia “much/very much improved” on dextromethorphan/quinidine versus 1‐patient on placebo. Dextromethorphan/quinidine did not worsen PD‐motor scores, was generally well tolerated, and was associated with more frequent adverse events. Conclusion : This study provides preliminary evidence of clinical benefit with dextromethorphan/quinidine for treating levodopa‐induced dyskinesia in PD. Larger studies with a longer treatment duration need to corroborate these early findings. © 2017 International Parkinson and Movement Disorder Society