Cascade of levodopa dose and weight-related dyskinesia in Parkinson's disease (LD-WD-PD cascade)

We have studied a cohort of 220 Parkinson's disease (PD) patients for risk factors of developing new dyskinesia. Twenty-nine patients were noticed to have developed new dyskinesia at the second assessment. The dyskinetic patients received significantly higher maximum level daily dose of levodopa. These patients had lost weight during the course of the disease from 72±15 to 66±17 kg, p=0.002. The dyskinetic patients received significantly higher daily dose of levodopa per kilogram body weight, 8.4±3.5 mg/kg vs. 6.0±3.9 mg, p=0.003. Weight-losers PD patients developed significantly more dyskinesia than non-weight losers—p=0.002. Logistic regression analysis revealed weight loss and daily levodopa dose per kilogram body weight to be the only significant factors for dyskinesia in addition to disease duration. There was a “dose response to developing dyskinesia” according to the increasing levodopa dose per kilogram body weight.     

Classifying risk factors for dyskinesia in Parkinson’s disease

BackgroundCurrently there is no classification of risk factors applicable to an individual patient with Parkinson’s disease for the development of dyskinesia.MethodsWe conducted literature search to identify and classifying risk factors into groups – (a) intrinsic vs extrinsic and (b) modifiable vs non-modifiable.ResultsYounger age, young age of onset and severity of PD are major intrinsic non-modifiable risk factors for dyskinesia, female gender is another factor but not independent of other factors. Genetic expression and plasticity may determine pre-disposition to age of onset of PD and dyskinesia, these are currently non-modifiable factors arising due to an interaction of intrinsic and extrinsic factors. Lower initial body weight and weight loss during the course of the disease increase the risk of dyskinesia. Levodopa dose per kilogram body weight is a more significant risk factor than absolute levodopa dose. Early use of longer acting non-levodopa (i.e. dopamine agonists) medications delays the onset of dyskinesia. Interaction between body weight, levodopa dose and mode and duration of drug delivery is a significant modifiable factor.ConclusionDyskinesia in PD arises as a consequence of the interaction of intrinsic versus extrinsic and modifiable versus non-modifiable factors. Identification and manipulation of modifiable factors for an individual patient may reduce the risk and burden of dyskinesia. Adjustment of levodopa dose according to body weight during the course of the disease seems to be a significant modifiable risk factor for dyskinesia.     

Dopaminergic treatment is associated with decreased body weight in patients with Parkinson's disease and dyskinesias

Background and purpose:  Several studies suggested that patients with advanced Parkinson's disease (PD) showed a too low body weight when compared with age-matched, healthy subjects. We aimed to investigate whether PD patients with dyskinesias display body weight alterations and to observe any correlations between medication and other putative determinants.
Methods:  Charts of 166 PD patients with fluctuations and dyskinesias, admitted within 6 months to a German movement disorders clinic, were investigated for body mass index (BMI), age at onset, disease duration, Unified Parkinson's Disease Rating Scale motor score, eating coordination and medication.
Results:  Analysis showed that 4.2% of PD patients were underweight (BMI < 18.5 kg/m²), 46.4% were normal (BMI > 18.5–25 kg/m²), 33.7% were overweight (BMI > 25–30 kg/m²), 15.7% were obese (BMI > 30 kg/m²). Daily levodopa dosage per kg and total dopaminergic dosage per kg body weight were negatively correlated with BMI. Overall, patients' BMI had not significantly changed within 2 years of follow-up.
Conclusions:  In sum, advanced PD patients showed a reduced BMI when compared with a control population obtained from an age-matched group taken from a survey of the German Federal Office for Statistics. Our findings indicate that patients with a lower BMI received a higher cumulative levodopa dosage and that levodopa may be responsible for weight loss in PD.     

Body weight influences pharmacokinetics of levodopa in Parkinson's disease

Changes in body weight may induce substantial variations in peripheral pharmacokinetics of drugs, but the relation between body weight and levodopa (LD) pharmacokinetics has never been investigated in Parkinson's disease. To address this issue, we conducted a pharmacokinetic study with 164 patients with sporadic Parkinson's disease. Patients underwent an oral acute LD test with 250 mg of LD, and pharmacokinetic variables were assessed at baseline and at 30, 60, 120, and 240 minutes after LD administration. Plasmatic-LD areas under the curve and body weight were significantly and inversely correlated as well as the elimination of the half-life of LD and body weight. In our sample, women were significantly lighter and had a significantly greater area under the curve than men. Moreover, a greater percentage of women showed LD peak-dose dyskinesias compared with men. Our findings suggest that lighter patients with Parkinson's disease probably receive a greater cumulative dosage of LD per kilogram of body weight during long-term treatment, because in clinical practice, LD is administered without any adjustment of the dose to body weight. This could explain gender differences for the development of LD-induced peak-dose dyskinesias observed during the course of the disease.     

Ten-year follow-up of Parkinson's disease patients randomized to initial therapy with ropinirole or levodopa.

In a 5-year, double-blind study, subjects with Parkinson's disease (PD) who were randomized to initial treatment with ropinirole had a significantly lower incidence of dyskinesia compared with subjects randomized to levodopa, although Unified Parkinson's Disease Rating Scale (UPDRS) motor scores were significantly more improved in the levodopa group. Subjects who completed the original study were eligible to participate in a long-term extension study conducted according to an open, naturalistic design and were evaluated approximately every 6 months until they had been followed for a total of 10 years. Comparing subjects randomized to initial treatment with ropinirole (n = 42) and levodopa (n = 27), the incidence of dyskinesia was significantly lower in the ropinirole group (adjusted odds ratio [OR] = 0.3; 95% confidence interval [CI]: 0.1, 1.0; P = 0.046) and the median time to dyskinesia was significantly longer (adjusted hazard ratio = 0.4; 95% CI: 0.2, 0.8; P = 0.007). The incidence of at least moderate wearing off ("off" time >/=26% of the awake day) was also significantly lower in the ropinirole group (adjusted OR = 0.3; 95% CI: 0.09, 0.03; P = 0.03). There were no significant differences in change in UPDRS activities of daily living or motor scores, or scores for the 39-item PD questionnaire, Clinical Global Impression, or the Epworth Sleepiness Scale. Early treatment decisions for individual patients depend largely on the anticipated risk of side effects and long-term complications. Both ropinirole and levodopa are viable treatment options in early PD.     

Selective blockade of D(3) dopamine receptors enhances the anti-parkinsonian properties of ropinirole and levodopa in the MPTP-lesioned primate

To date, the lack of highly selective antagonists at the dopamine D(3) receptor has hampered clarification of their involvement in the actions of currently used therapies in Parkinson's disease. However, the novel benzopyranopyrrole, S33084, displays greater than 100-fold selectivity as an antagonist for D(3) versus D(2) receptors and all other sites tested. S33084 was administered to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned marmosets previously primed with levodopa to elicit dyskinesia. Administered alone, S33084 exerted a modest, but significant, anti-parkinsonian effect without provoking dyskinesia. At low D(3)-selective doses (0.16 and 0.64 mg/kg), S33084 potentiated, though to different extents and in qualitatively different ways, the anti-parkinsonian actions of both ropinirole and levodopa. At these doses, S33084 did not significantly modify levodopa-induced or ropinirole-induced dyskinesia. These data suggest that ropinirole and levodopa do not exert their anti-parkinsonian or pro-dyskinetic actions via D(3) receptor stimulation. Indeed, stimulation of D(3) receptors may be detrimental to the anti-parkinsonian properties of D(2)/D(3) agonists. Selectivity for stimulation of D(2), over D(3), receptors may therefore be a beneficial property of dopamine receptor agonists in management of motor symptoms of Parkinson's disease patients with established dyskinesia.     

Onset of dyskinesia with adjunct ropinirole prolonged‐release or additional levodopa in early Parkinson's disease

Levodopa‐induced dyskinesia can result in significant functional disability and reduced quality of life in patients with Parkinson's disease (PD). The goal of this study was to determine if the addition of once‐daily ropinirole 24‐hour prolonged‐release (n = 104) in PD patients not optimally controlled with levodopa after up to 3 years of therapy with less than 600 mg/d delays the onset of dyskinesia compared with increasing doses of levodopa (n = 104). During the study, 3% of the ropinirole prolonged‐release group (mean dose 10 mg/d) and 17% of the levodopa group (mean additional dose 284 mg/d) developed dyskinesia (P < 0.001). There were no significant differences in change in Unified Parkinson's Disease Rating Scale activities of daily living or motor scores, suggesting comparable efficacy between the two treatments. Adverse events were comparable in the two groups with nausea, dizziness, insomnia, back pain, arthralgia, somnolence, fatigue, and pain most commonly reported. Ropinirole prolonged‐release delayed the onset of dyskinesia with comparable efficacy to increased doses of levodopa in early PD patients not optimally controlled with levodopa. © 2010 Movement Disorder Society     

Ropinirole therapy for Parkinson's disease

Ropinirole (Requip, GlaxoSmithKline) is a novel nonergoline dopamine D2 agonist indicated for the treatment of early and advanced Parkinson's disease. It is mainly metabolized by the liver and its elimination half-life is approximately 5.8 h. When used as monotherapy in early Parkinson's disease, ropinirole improves signs and symptoms of the disorder. When used as an adjunct to levodopa in advanced Parkinson's disease patients with motor fluctuations, ropinirole reduces off time and allows a reduction of levodopa dose. The initial use of ropinirole in early Parkinson's disease to which levodopa is added when necessary, has been demonstrated to lead to a lower incidence of dyskinesias compared with treatment with levodopa alone. An 18F-dihydroxyphenylalanine positron emission tomography study suggested the possibility that ropinirole could slow the progression of loss of dopamine neurons compared with treatment with levodopa but this remains to be proven. Side effects of ropinirole include nausea, somnolence, edema, orthostatic hypotension, hallucinations and dyskinesia. A once-daily formulation of ropinirole is currently in development that has the potential for greater convenience, improved tolerability and greater efficacy.     

Clinical-pathological study of levodopa complications.

We sought to determine the continued benefit and the pattern of motor complications of long-term levodopa treatment in Parkinson's disease. Patients were evaluated between 1968 and 1996. Only those who had an adequate levodopa trial and in whom autopsy revealed Lewy body Parkinson's disease were included. Total levodopa and mean daily dose were calculated in each case. Dyskinesia, wearing-off and on-off were collectively classified as motor adverse effects and reported as cumulative incidence. Forty-two patients (male, 30; female, 12) with mean 15.9 years of illness and 9.1 years follow-up received on average 500-mg levodopa daily over 9.8 years. Seventeen of 21 patients assessed during the last 18 months of life reported some motor benefit. Adverse effects were seen in 71.4% of patients. The most common was dyskinesia, in 61.9%; wearing-off in 35.7%; and on-off in 16.7% of patients. The earliest adverse effect was dyskinesia and the last to emerge was on-off. Isolated dyskinesia was seen in 35.7% and wearing-off in 7.1% of patients; 15.5% of patients developed dyskinesia after 2.6 years and 31% after 6.4 years on levodopa. We concluded that levodopa benefit declined and adverse effects increased with time. Dyskinesia was the earliest and the most common isolated adverse effect.     

Ropinirole as an adjunct to levodopa in the treatment of Parkinson's disease: a 16-week bromocriptine controlled study

Background: and objectives Ropinirole is a non-ergoline, selective dopamine D₂ agonist. The aim of this study was to evaluate the efficacy and safety of ropinirole as an adjunct to levodopa in the treatment of Parkinson's disease (PD) complicated by motor fluctuations. Methods: A total of 76 patients with PD (Hoehn and Yahr stage II to IV) were included in this trial. Each patient was randomly allocated to receive either ropinirole (n = 37) or bromocriptine (n = 39) as an adjunct to levodopa over a 16-week period. Ropinirole and bromocriptine were titrated for optimal efficacy and tolerability. This optimal dose was then maintained for the rest of the study. Response rate was defined as the percentage of patients who achieved at least a 20 % reduction in levodopa dose. Clinical status was also assessed using the Unified Parkinson's Disease Rating Scale (UPDRS), Clinical Global Impression (CGI), and reduction in time spent ‘off’. Results: Ropinirole produced a significantly greater response rate than bromocriptine (odds ratio 2.995, 95 % C. I. (1.157, 7.751) p < 0.05). There was also a statistically significant difference between the groups in the proportion of patients who were ‘improved’ on the CGI improvement scale (91.9 % for ropinirole, 74.3 % for bromocriptine, p = 0.046). Other measures, including at least a 20 % improvement in the UPDRS motor score (70 % for ropinirole and 63.3 % for bromocriptine), and a 20 % reduction in ‘off’ duration (81 % for ropinirole and 52.4 % for bromocriptine) showed a trend in favour of ropinirole. There was no significant difference between the two groups in the overall incidence of adverse effects (ropinirole, 59.5 %; bromocriptine, 59 %). In each group, the most common side-effects were dizziness, dyskinesia and nausea/vomiting. No patients were withdrawn from the study because of side-effects. Conclusion: Ropinirole was found to be safe and well-tolerated. Ropinirole as an adjunct to levodopa in the treatment of PD with motor fluctuation was associated with more significant reduction of levodopa dose and, on one form of analysis, with significantly greater improvement in CGI ratings than bromocriptine. On the other efficacy measures the two drugs were comparable. Received: 4 September 2001, Received in revised form: 8 May 2002, Accepted: 31 July 2002 This study was supported by SmithKline Beecham Korea and presented at the XIII International Congress on Parkinson's Disease, Vancouver, Canada, July 24–28, 1999. Correspondence to Joo-Hyuk Im, MD     

Long term role of pergolide as an adjunct therapy in Parkinson's disease: influence on disability, blood pressure, weight and levodopa syndrome

Pergolide is a dopamine agonist acting on D1 and D2 receptors and has been used as an adjunct therapy with levodopa. We have retrospectively investigated its role over a duration of upto six years in Parkinson's disease (PD) patients to study: (1) its influence on the progression of disability related to PD; (2) effect on blood pressure and weight during the treatment period; (3) whether the use of pergolide has a long term levodopa sparing effect; (4) and how is it tolerated during this period? We studied 43 patients who had been on adjunct therapy with pergolide in addition to levodopa for more than six months. Mean age was 66 years, mean duration of PD prior to adding pergolide was 8 years and final assessment was done after a mean duration of adjunct therapy of 29 (6-72) months. There was no progression of disease disability as assessed on Hoehn and Yahr stage (p=0.09) and Webster score (p=0.20), while there was an improvement in symptom score (p=0.001). There was an insignificant reduction in the dose of levodopa at final assessment from 630 to 535mg (p=0.06). A significant number of patients were able to discontinue taking selegiline (p=0.002). There was no change in the number of patients with hallucinations (p=0.15) and dyskinesia (p=0.09). There was a significant fall in weight (p=0.02), systolic (p=0.023) and diastolic blood pressure (p=0.03). This fall did not correlate with age, dose of pergolide or levodopa or disease severity but was influenced by duration of treatment. Ten patients discontinued pergolide for minor reasons after a mean duration of therapy for 23 months. We conclude that pergolide is a valuable adjunct therapy with levodopa over a duration of upto six years to maintain control of motor symptoms of Parkinson's disease.     

Age and body weight adjusted warfarin initiation program for ischaemic stroke patients

Background:  Despite its proven effect, anticoagulation is not recommended to the acute ischaemic stroke due to the risk of bleeding complications. The purpose of this study is development of individualized warfarin initiation program for acute or subacute stroke patients.
Methods:  Among stroke patients who regularly visited out-patient clinics, we included patients who have continuously taken the same dose of warfarin as the prothrombin time remained at target International Nomarlized Ratio (INR). We assessed potential variables that affect the maintenance dose of warfarin. Using these variables, we developed an individualized warfarin initiation program.
Results:  The median warfarin maintenance dose (interquartile range) in the 321 included patients was 4 (3–5) mg per day. Age (adjusted R ² = 0.221, P  <   0.001) and body weight (added to age, adjusted R ² = 0.238, P  =   0.008) were significant predicting factors of the dose. We classified the maintenance doses into high (HG), standard, and low group (LG) based on the distribution of maintenance doses. Decision tree analysis categorized younger (≤55 years old) and heavier (≥55 kg) patients into HG, and very old (≥80 years old) or low body weight (<55 kg among those >56 years old) patients into LG. We recommend 7 mg of warfarin as a standard initial dose, but 10 mg was recommended for HG patients and 5 mg for LG.
Conclusion:  We expect that this individualized program may reduce the time to target INR without excessive anticoagulation. Further prospective studies are needed to reveal the efficacy and safety of applying this program for acute stroke patients.     

Do dopamine agonists or levodopa modify Parkinson's disease progression?

During the past decade, in vivo imaging of the nigrostriatal dopaminergic system has been developed as a research tool to monitor progressive dopaminergic neuron loss in Parkinson's disease (PD) and to assess the effect of medication on imaging outcomes. Recently two similar studies compared the effect of initial treatment with a dopamine agonist (pramipexole (CALM-PD CIT) or ropinirole (REAL-PET)) or levodopa on the progression of PD as measured by [¹²³I] β -CIT or [¹⁸F]Dopa imaging. These two clinical imaging studies targeting dopamine function with different imaging ligands and technology both demonstrate slowing in the rate of loss of [¹²³I] β -CIT or [¹⁸F]Dopa uptake in early PD patients treated with dopamine agonists compared with levodopa. The relative reduction in the per cent loss from baseline of [¹²³I] β -CIT uptake in the pramipexole versus the levodopa group was 47% at 22 months, 44% at 34 months and 37% at 46 months after initiating treatment. The relative reduction of ¹⁸F-dopa uptake in the ropinirole group versus the levodopa group was 35% at 24 months. These results should be very cautiously interpreted with regard to the effect of dopamine agonists or levodopa on clinical disease progression. These data highlight the need to compare imaging outcomes of dopamine neuronal loss with multiple meaningful clinical endpoints of disease progression in placebo controlled, larger and long-term studies.     

Efficacy of sinemet CR4 in subgroups of patients with Parkinson''s disease.

The efficacy of Sinemet CR4 (50/200) was compared to standard Sinemet (25/100) in an open label crossover study in 22 patients with Parkinson's disease. All patients experienced end of dose failure and 11 had dyskinesia. Unified Parkinson's disease, Hoehn and Yahr, Schwab and England scores, number of hours on per day, number of hours of dyskinesia per day, daily dose of levodopa, and number of doses per day were monitored at the end of each treatment period and the results compared. The only significant difference in these parameters between the CR4 and standard Sinemet treatment periods in the entire group was a decrease in hours of dyskinesia per day. Two subgroups of CR4 responders were specifically examined. The first subgroup was characterised by a significant increase in on time per day with CR4 therapy. These patients had an older age of onset of Parkinson's disease and a shorter duration of disease and fluctuations than the rest of the patients. The second subgroup was characterised by the presence of dyskinesia with standard Sinemet therapy and a significant decrease in hours of dyskinesia per day with CR4 therapy. Both subgroups required a significantly higher daily dose of levodopa while on CR4. It is concluded that CR4 may be useful in increasing hours on per day in subgroups of Parkinson's disease patients who have less severe fluctuations. It may also be useful in decreasing the number of hours of dyskinesia per day.     

Does combined levodopa and bromocriptine therapy in Parkinson's disease prevent late motor complications?

Levodopa-carbidopa (LD) in low dosages adequately controls symptoms in most patients with Parkinson's disease and delays the appearance of fluctuations and dyskinesias. It has been suggested that early combination therapy with bromocriptine and levodopa delays or prevents the onset of late treatment complication associated with LD monotherapy in Parkinson's disease. We have conducted this study to assess the possible benefit of combined therapy compared with levodopa monotherapy. Seventy-eight previously untreated patients with Parkinson's disease were recruited over a period of 54 months and randomly allocated to either a levodopa-carbidopa (LD) Group or a levodopa-carbidopa in combination with low-dose bromocriptine (LD-Br) Group. The appearance of motor complications determined the end point of the study. We gradually increased the doses of bromocriptine (2.5–15 mg/d) or levodopa (125–500 mg/d) until the maximum "on" time was reached. In six patients, the doses of levodopa had to be increased up to the optimal dose (625–1000 mg/day). In the last evaluation the on-time and parkinsonian disability were similar in both treatment groups. We did not find statistically significant differences in the frequency of motor complications when comparing the two groups of treatment. Our study suggests that early combination of levodopa and bromocriptine does not confer any clinical benefit over levodopa alone in treating early Parkinson's disease, nor will it influence the evolution of the disease.     

A randomised controlled study comparing bromocriptine to which levodopa was later added, with levodopa alone in previously untreated patients with Parkinson''s disease: a five year follow up.

This pilot study was performed to compare the occurrence of long term motor complications in Parkinson's disease when the introduction of levodopa was delayed by an initial treatment with high doses of bromocriptine alone. The trial was a prospective randomised controlled study comparing 31 previously untreated patients with Parkinson's disease initially given bromocriptine alone to which levodopa was later added (group B/D) and 29 other previously untreated patients with Parkinson's disease immediately given levodopa alone (group D). The end point was the occurrence of the first motor complications (wearing off or dyskinesia). Group B/D patients received bromocriptine (52 (SEM 5) mg/day) for 2.7 years, to which levodopa was later added (471 (SEM 46) mg/day). Group D patients received a comparable dose of levodopa alone (569 (SEM 47) mg/day). Both had similar disability scores at the end of the study. Motor complications were fewer and appeared later in group B/D than in group D (56% after 4.9 (SEM 0.5) years of treatment v 90% after 2.7 (SEM 0.5) years, p < 0.01). Wearing off appeared later (p < 0.01) in group B/D (4.5 (SEM 0.6) years) than in group D (2.9 (SEM 0.6) years). Peak dose dyskinesia occurred less often in group B/D patients (three v 14 cases, p < 0.01). This study showed that a three year initial monotherapy with high doses of bromocriptine followed by addition of levodopa delayed the occurrence of long term motor complications usually found in patients with Parkinson's disease treated with levodopa alone from the beginning.     

High dose naltrexone for dyskinesias induced by levodopa

Ten patients with Parkinson's disease and levodopa induced dyskinesias (LIDs) took part in this randomised, placebo controlled, double blind, crossover trial to assess the efficacy and tolerability of high dose oral naltrexone for LIDs in Parkinson's disease. Patients received naltrexone (5 mg/kg/day) or placebo for 2.5 weeks with 1 week wash out in between. Dyskinesias and motor function were assessed with a levodopa challenge, unified Parkinson's disease rating scale (UPDRS), the unified dyskinesia rating scale (UDRS), and patient diaries. Eight patients completed the trial. There was a small reduction in LIDs measured by patient diaries with naltrexone (20.5 (SD 24.9)%) compared with placebo (-4.1 (SD 22.6)%), p<0.05, although no difference was found by other subjective or objective measures. Naltrexone was well tolerated and caused no significant differences in UPDRS motor scores or off time. This study suggests that short term therapy with high dose naltrexone (250-350 mg/day) has no or minimal effect on reducing LIDs in Parkinson's disease.     

Carnitine does not improve weight loss outcomes in valproate-treated bipolar patients consuming an energy-restricted, low-fat diet

Objectives:  Carnitine deficiency impairs fatty acid β -oxidation and may partly explain weight gain in valproate-treated patients. The aim of this study was to determine whether l -carnitine supplementation improves weight loss outcomes in bipolar patients taking sodium valproate.
Methods:  Sixty bipolar patients with clinically significant weight gain thought to be related to sodium valproate, who had been taking sodium valproate for ≥6 months, were randomized to l -carnitine (15 mg/kg/day) or placebo for 26 weeks, in conjunction with a moderately energy-restricted, low-fat diet. The primary outcome measure was weight change.
Results:  l -carnitine had no effect on mean weight loss compared with placebo (−1.9 kg versus − 0.9 kg) ( F  = 0.778, df = 1,58, p = 0.381). The number of people in each group able to lose any weight was identical (      = 0, p = 1.0); more patients in the carnitine group (nine versus five) achieved a clinically significant weight loss (≥5%) but this was not statistically significant (p = 1.0, Fisher's exact test).
Conclusions:  At the dose prescribed in this study carnitine supplementation did not improve weight loss outcomes in valproate-treated bipolar patients consuming an energy-restricted, low-fat diet.     

Selegiline and levodopa in early or moderately advanced Parkinson's disease: a double-blind controlled short- and long-term study

Abstract– Selegiline 10 mg per day was compared to placebo as an adjunct to levodopa treatment in this double-blind study of early or moderately advanced Parkinson's disease. Thirty-eight patients completed an initial cross-over trial comprising two treatment periods, each of eight weeks, with a four weeks'wash-out period between them. Thirty of the patients continued in a long-term, double-blind parallel trial with a mean duration of 16 months (range 6–30 months). Selegiline treatment allowed a significant reduction of the necessary daily levodopa dose in both parts of the study and of the daily dosing frequency in the long-term investigation. In spite of this reduction of levodopa dose, an improvement was noted in tremor during the short-term selegiline periods. The side-effects were slight and related to dopamine effects and disappeared after reduction of levodopa-dose. The results support the use of selegiline as an early adjunctive treatment in Parkinson's disease.     

Slower progression of Parkinson's disease with ropinirole versus levodopa: The REAL-PET study

Preclinical studies suggest ropinirole (a D2/D3 dopamine agonist) may be neuroprotective in Parkinson's disease (PD), and a pilot clinical study using (18)F-dopa positron emission tomography (PET) suggested a slower loss of striatal dopamine storage with ropinirole compared with levodopa. This prospective, 2-year, randomized, double-blind, multinational study compared the rates of loss of dopamine-terminal function in de novo patients with clinical and (18)F-dopa PET evidence of early PD, randomized 1 to 1 to receive either ropinirole or levodopa. The primary outcome measure was reduction in putamen (18)F-dopa uptake (Ki) between baseline and 2-year PET. Of 186, 162 randomized patients were eligible for analysis. A blinded, central, region-of-interest analysis showed a significantly lower reduction (p = 0.022) in putamen Ki over 2 years with ropinirole (-13.4%; n = 68) compared with levodopa (-20.3%; n = 59; 95% confidence interval [CI], 0.65-13.06). Statistical parametric mapping localized lesser reductions in (18)F-dopa uptake in the putamen and substantia nigra with ropinirole. The greatest Ki decrease in each group was in the putamen (ropinirole, -14.1%; levodopa, -22.9%; 95% CI, 4.24-13.3), but the decrease was significantly lower with ropinirole compared with levodopa (p < 0.001). Ropinirole is associated with slower progression of PD than levodopa as assessed by (18)F-dopa PET.