PARKINSON''S DISEASE TREATED WITH SINEMET OR MADOPAR

92 patients with Parkinson's disease not previously treated with levodopa were considered as eligible for this triple-blind trial. Patients were allocated at random to treatment with either levodopa + benserazide ratio 4:1 (Madopar) or levodopa + carbidopa ratio 10:1 (Sinemet) using dosage schedules recommended by the manufacturers which they had to adhere to for 6 months. Unless prohibitive side-effects occurred daily maximum dosage of 800 mg levodopa + 200 mg benserazide respectively 1,500 mg levodopa + 150 mg carbidopa were obtained after 6 weeks and 3 weeks, respectively. The effect of the two schedules on the Parkinsonian symptoms were equal and appeared equally fast. The frequency of gastrointestinal side-effects and involuntary movements were significantly higher and more severe for Sinemet than for Madopar. These side effects are usually symptoms of levodopa overdosing, but whether or not a different dosage schedule with Sinemet would have given fewer side-effects without concurrent lower efficacy remains open to speculation. The treatment schedules did not differ with regard to other side-effects and influence on blood pressure. Neither treatment seemed to influence liver function, renal function and hematological parameters in a statistically way.     

A controlled release form of Madopar in Parkinsonian patients with advanced disease and marked fluctuations in motor performance

Flucuations in motor performance is a major problem in long-term levodopa treatment of Parkinsonian patients. A slow release preparation of levodopa with benserazide, Madopar HBS, has been developed in an attempt to decrease this problem. Eleven of 22 Parkinsonian patients with advanced disease and marked fluctuations experienced long-lasting benefit with reduction of their fluctuations in motor performance on treatment with Madopar HBS; 11 dropped out within the first 5 months of the trial. This was probably due to lack of experience with the effect of this new slow-release formulation. Nine patients (82%) required an additional dose of standard Madopar, especially in the morning. Significant improvements were found for akinetic phenomenon and dystonic cramps, and with the global evaluation of motor fluctuations. The occurrence of peak dose dyskinesia remained unchanged. No abnormalities in laboratory values were found.     

Benserazide decreases central AADC activity, extracellular dopamine levels and levodopa decarboxylation in striatum of the rat

Summary. In Parkinsonian patients treated with levodopa, peripheral decarboxylase inhibitors like carbidopa and benserazide are used to increase the central availability of levodopa. In experimental animal studies, this clinical situation is mimicked. However, at the dose used in many animal studies, both benserazide and carbidopa pass the blood brain barrier. In this study, we investigated to what extent their presence in brain inhibits striatal aromatic amino acid decarboxylase activity. At 50 mg/kg i.p., both carbidopa and benserazide decreased striatal decarboxylase activity. At 10 mg/kg i.p., only benserazide decreased the enzyme activity, but this did not change extracellular dopamine in striatum and allowed dopamine levels to increase after levodopa administration. In contrast, the inhibition of central decarboxylase activity by 50 mg/kg benserazide decreased striatal dopamine levels and prevented the levodopa-induced increase. Therefore, it is important to carefully consider the dose of the peripheral decarboxylase inhibitor used when the central effects of levodopa are studied. Received June 26, 2000; accepted December 7, 2000     

The clinical efficacy of single morning doses of levodopa methyl ester: dispersible Madopar and Sinemet plus in Parkinson disease.

For many patients with Parkinson disease and levodopa-related motor fluctuations, the latency to onset of action of a single dose of a levodopa preparation may be both long and variable. In an effort to find a more rapidly acting and reliable preparation of levodopa, we therefore studied the efficacy of single doses of an oral solution of 250 mg of levodopa methyl ester (ME) with benserazide, 50 mg and of a molar equivalent dose of dispersible Madopar (DM) (50/200) in 13 patients in the fasting state after overnight drug withdrawal. The response of seven of these patients was compared to that after two Sinemet 25/100. The latency to "on" was equally fast with ME and DM, and significantly faster than after standard Sinemet. The duration of "on" was similar with all three. Because of this more rapid relief of "off" periods, both ME and DM offer a potential clinical advantage over standard preparations of levodopa.     

A comparison of the effects of controlled-release levodopa (Madopar CR) with conventional levodopa in late Parkinson''s disease.

In this multicentre study a controlled-release formulation of levodopa and the decarboxylase inhibitor benserazide (Madopar CR) was evaluated in patients with Parkinson's disease exhibiting dose-related fluctuations in motor performance in response to conventional levodopa preparations. The effect of Madopar CR, with or without conventional levodopa/benserazide, on the proportion of time spent "on", "off" or "intermediate" was compared with that of previous conventional levodopa/decarboxylase inhibitor therapy. Evaluation of the two periods of optimum therapy was based on both patient diary data and investigator opinion. Forty seven patients completed the study but full patient diaries were available for only 37. The mean optimum total daily dosage of conventional Madopar was 820 mg taken in a mean of 6.4 doses, compared with a mean optimum daily dosage of combined Madopar CR and conventional Madopar of 1088 mg, taken in a mean of 5.2 doses. Conventional Madopar was taken in addition to Madopar CR in all but eight patients. Madopar CR was felt to be advantageous in 83% and disadvantageous in 11% of patients completing the study. Considering the 37 patients for whom diary data were available, Madopar CR therapy resulted in an increase in the mean time spent "on" (p = 0.016) and a decrease in the mean time spent "off" (p = 0.029) compared with conventional Madopar alone. Individually 25 out of 37 had an increase in "on" time and 19 out of 37 experienced a decrease in "off" time. Thus Madopar CR was found to be beneficial in a significant proportion of patients experiencing fluctuations in response to conventional levodopa.     

Induction of aromatic-l-amino acid decarboxylase by decarboxylase inhibitors in idiopathic parkinsonism

We evaluated the effect of administration of L-dopa, alone or in combination with a peripheral decarboxylase inhibitor, on plasma levels of aromatic-L-amino acid decarboxylase (ALAAD). After single-dose administration of L-dopa plus benserazide (Madopar) in healthy subjects and in chronically treated patients with parkinsonism, plasma ALAAD followed for 2 to 3 hours fell, but returned to predosing levels within 90 minutes. Four groups of patients with idiopathic parkinsonism were studied during chronic treatment: Group I, no L-dopa treatment (n = 31); Group II, L-dopa alone (n = 15); Group III, L-dopa plus benserazide (n = 28); and Group IV, L-dopa plus carbidopa (Sinemet, n = 30). Plasma ALAAD 2 hours after dosing was normal in Groups I and II. ALAAD was increased threefold in Groups III and IV, suggesting induction of ALAAD by the coad-ministration of a peripheral decarboxylase inhibitor. In a study of 3 patients in whom L-dopa/benserazide was started, plasma ALAAD rose gradually over 3 to 4 weeks. Further detailed pharmacokinetic studies of L-dopa, dopamine, and ALAAD in plasma and cerebrospinal fluid are required to determine if the apparent ALAAD induction by a peripheral decarboxylase inhibitor may be related to the loss of clinical efficacy of combination therapy in some patients and how it is related to end-of-dose deterioration and on-off phenomena.     

Mesulergine in early Parkinson''s disease: a double blind controlled trial.

The efficacy and tolerance of treatment with an 8-alpha-amino-ergoline derivative CU32-o85, Mesulergine, were compared with levodopa/benserazide (Madopar) in a 3 month double-blind controlled trial in 31 patients with Parkinson's disease, not previously treated with levodopa. The two treatments were equally well tolerated, and neither dyskinesias nor dose-related fluctuations developed. In 90% of the patients treated with Mesulergine, Parkinsonian symptoms improved, and at the dose given the overall therapeutical response was two-thirds that of levodopa. During further 9 months of open study the beneficial effect was maintained equally well in both groups. Compared with other dopamine agonists Mesulergine has a considerable antiparkinsonian effect. Unfortunately, further clinical evaluation of the compound recently has been stopped owing to sex and species specific histological alterations in rats. It is suggested that Mesulergine derivatives might well be of value in future treatment of early Parkinson's disease and of late incompensated stages.     

Open study of sustained-release formulation of levodopa and benserazide in parkinsonian patients

The efficacy of a novel oral sustained-release preparation of levodopa/benserazide (Madopar HBS) was compared to that of previous conventional levodopa/benserazide treatment in 15 patients with idiopathic Parkinson's disease and with severe fluctuations in motor response to long-term levodopa therapy. In ten patients who suffered from clear-cut "end-of-dose" deterioration, significant benefit was obtained on HBS form, while 5 patients did not respond well to the new levodopa preparation. Plasma levels of levodopa were more stable with HBS compared to conventional levodopa preparation in our patients, although doses of HBS form required for an optimal response averaged 1.48 times that of previous conventional levodopa.     

The use of lisuride in the treatment of multiple system atrophy with autonomic failure (Shy-Drager syndrome).

In a controlled trial lisuride, an ergolene derivative with dopamine receptor agonist properties was given maximum tolerated doses (2.4 mg/day) to seven patients with multiple system atrophy with autonomic failure (Shy-Drager syndrome). Improvement in Parkinsonian features occurred in only one patient and another patient who had been deriving marked benefit from levodopa treatment before the study began failed to respond to large doses of lisuride. Psychiatric side effects (including nightmares, isolated visual hallucinations and toxic confusional states) were the dose-limiting factor in six patients. A modest reduction in orthostatic hypotension occurred in two patients, one of whom had experienced an aggravation of this disturbance on levodopa and bromocriptine. Destruction of post-synaptic dopamine receptors and damage to central noradrenergic systems may offer an explanation for the lack of therapeutic effect of lisuride.     

Effect of hypoglycaemia,TRH and levodopa on plasma growth hormone,prolactin, thyrotropin and cortisol in Parkinson's disease before and during therapy

Summary Thirteen drug-free and not severely affected patients with idiopathic Parkinson's disease underwent an insulin-hypoglycaemia test, a TRH test and a levodopa test. The responses of growth hormone, prolactin, cortisol and thyrotropin were measured, and retested under stable therapy with levodopa and benserazide. Mean basal and stimulated hormonal concentrations were in the normal range before and during therapy. Minor abnormalities were observed in individual cases, but did not indicate a hypothalamic dopamine deficit.     

Influence of meal ingestion time on pharmacokinetics of orally administered levodopa in parkinsonian patients

The influence of meal ingestion time on rate and extent of oral levodopa absorption was evaluated in a group of 17 patients, after administration of their usual second daily dose of levodopa plus carbidopa (Sinemet 10:1) or benserazide (Madopar 4:1). Standard meals were consumed by the patients after they had fasted 15-17 h, on one occasion 30 min before ingestion of the levodopa "study dose" and, at another time, 2 h after ingestion of the same dose. This study dose, ranging from 50 to 250 mg levodopa, was given to the patients at 11 a.m., 4 h after their first morning dose. Time to peak plasma levodopa concentration increased threefold (from 45 +/- 23 to 134 +/- 76 min, p less than 0.001), when levodopa was administered after meals. Area under the 6-h plasma concentration-time curve for levodopa was decreased in 10 subjects, unchanged in three and higher in four after ingestion of meals, the latter finding probably resulting from an erratic absorption even at fasting. On the whole, levodopa absorption proved significantly lower (p less than 0.01), on the average 15%. Similarly, peak plasma levodopa concentrations were lower in 12 patients, unchanged in two, and higher in three, with an overall significant decrease (p less than 0.001) of 30% on the average. The data confirm the importance of meal ingestion time in relation to levodopa dose as a determinant of drug absorption.     

Treatment of idiopathic parkinsonism with l-dopa in the absence and presence of decarboxylase inhibitors: effects on plasma levels of l-dopa,dopa decarboxylase,catecholamines and 3-O-methyl-dopa

Summary The effect of levodopa (l-dopa), alone or in combination with a peripheral decarboxylase inhibitor (PDI), on plasma levels of aromatic-l-amino acid decarboxylase (ALAAD, = dopa decarboxylase), l-dopa, 3-O-methyl-dopa (3-OMD), dopamine (DA), noradrenaline, adrenaline and dopamine beta-hydroxylase has been studied. In healthy subjects and in patients with parkinsonism plasma ALAAD level fell after administration of l-dopa + benserazide, but returned to previous levels within 90 min. In a cross-sectional study blood was obtained, 2 h after dosing, from 104 patients with idiopathic parkinsonism, divided into four groups: no l-dopa treatment (group 1), l-dopa alone (group 2), l-dopa + benserazide (Madopar) (group 3) and l-dopa + carbidopa (Sinemet) (group 4). Plasma ALAAD, which was normal in groups 1 and 2, was increased 3-fold in groups 3 and 4, indicating that there was induction of ALAAD by the co-administration of PDI. Despite this induction of ALAAD, in groups 3 and 4, with half the daily l-dopa dose compared with group 2, plasma l-dopa and 3-OMD levels were 5 times higher, while plasma DA levels were not different. The DA/l-dopa ratio was decreased 5-fold in group 2 and 16-fold in groups 3 and 4 as compared with group 1. Neither 3-OMD levels nor 3-OMD/l-dopa ratios correlated with the occurrence of on-off fluctuations. In a longitudinal study of three patients started on Madopar treatment the induction of plasma ALAAD was found to occur gradually over 3–4 weeks. Further detailed pharmacokinetic studies in plasma and cerebrospinal fluid are required in order to elucidate whether the ALAAD induction by PDI may be related to the loss of clinical efficacy of combination therapy in some patients and how it is related to end-of-dose deterioration and on-off phenomena.     

Choice reaction time after levodopa challenge in parkinsonian patients

Various types of choice reaction time paradigms demonstrated deficits in the preparation and execution of movements in parkinsonian subjects. These studies showed controversial results, since they included parkinsonian individuals being: (i) previously untreated; (ii) off; or (iii) on anti-parkinsonian medication. Moreover, these trials do not take into consideration the acute effects of levodopa administration. Objective of this study was to determine the effect of long-term dopaminergic substitution therapy within a standardized levodopa challenge test in combination with a repeatedly performed choice reaction time task in parkinsonian individuals. Parkinsonian participants consisted of previously untreated, so-called "de-novo" patients and of individuals, who were chronically substituted with dopaminergic drugs, but were taken off medication for at least 12 h. All participants took 250 mg levodopa/benserazide after assessment of baseline data. Then we repeatedly measured choice reaction- and movement time within the next 90 min. No significant change of the assessed task data appeared in the "de-novo" group, but reaction- and movement time significantly shortened in previously treated subjects. Sedative effects of levodopa and/or dopaminergic overstimulation hypothetically explain the results of the previously untreated patients, whereas long-term dopaminergic substitution therapy hypothetically causes tolerance to these phenomena in treated parkinsonian individuals. Future studies on parkinsonian subjects should discuss their results on the basic pathophysiology or basal ganglia dysfunction in the light of a putative impact of long-term anti-parkinsonian drug therapy.     

Visual and auditory evoked responses in patients with Parkinson's disease.

Visual evoked responses were obtained in 47 Parkinsonian patients and 26 age-matched controls. The stimulation to binocular and uniocular latency of the major positive peak was longer in the Parkinsonian patients and its amplitude was smaller than in the control subjects. There was a large interocular difference suggesting that at least part of the delay occurs at prechiasmatic level. The latency and amplitude varied markedly following ingestion of levodopa as Sinemet. Auditory evoked potentials were obtained in 16 Parkinsonian patients and 11 age-matched controls. The latency of the NV wave was prolonged in the former although the amplitude was the same, suggesting that the abnormality may be a widespread one.     

Controlled release levodopa-carbidopa (CR-5) in the management of parkinsonian motor fluctuations

Parkinsonian patients receiving long-term levodopa-carbidopa (Sinemet) therapy often develop fluctuations in motor performance. Although maintenance of stable levels of plasma levodopa by means of its continuous intravenous infusion diminishes these fluctuations, practical limitations attending this therapeutic approach have prompted continuing attempts to develop oral controlled release levodopa-carbidopa formulations. In a double-blind, crossover clinical trial, one such preparation, CR-5 (Merck, Sharp & Dohme), produced significantly less plasma levodopa variations and substantially improved motor performance over Sinemet in 15 patients with mild to moderate fluctuations, all but one of whom chose to continue on CR-5 therapy after the study. Eight patients with severe motor fluctuations could not adjust to this preparation during the open phase and consequently withdrew from the study. Subjectively, most patients noted the convenience of less frequent dosing, improved sleep, and the amelioration of early morning akinesia and dystonia.     

Dopaminergic responsiveness to apomorphine after chronic treatment with subcutaneous lisuride infusion in Parkinson's disease

The aim of this study was to assess whether or not continuous infusion of lisuride in combination with intermittent levodopa-carbidopa administration was associated with tolerance. Intravenous apomorphine was given to four patients before initiation of chronic treatment with subcutaneous lisuride infusion and oral levodopa. The study was repeated under identical conditions after a mean of 18 months of treatment. In no case was the motor response induced by apomorphine infusion reduced as compared to baseline assessment. Choreic dyskinesias accompanying the "on" state were enhanced in all patients. These findings suggest that chronic continuous infusion of a dopamine agonist like lisuride, associated with oral levodopa, is not accompanied by tolerance or down-regulation of striatal dopaminergic receptors.     

Therapeutic effect of lisuride in advanced Parkinson's disease

The therapeutic effects of lisuride hydrogen maleate, a central dopamine agonist, were examined in 15 patients with advanced Parkinson's disease no longer satisfactorily responding to levodopa. A significant improvement (p less than 0.01) in the total Parkinson's disease disability score was obtained by the addition of lisuride to levodopa therapy. The clinical assessment in the follow-up was performed with 2 different disability scales that yielded a more precise evaluation of the efficacy of lisuride, an efficacy that, as with other dopaminergic drugs, showed a slight decrease in time after a mean of 3 months. No important adverse effects were noticed. The only limitation of the use of lisuride was the occurrence of reversible psychic disturbances. It is concluded from this study that lisuride is a valuable tool in the management of advanced Parkinson's disease that allows for a reduction of the side effects of levodopa therapy in the long-term treatment of the disease.     

Continuous lisuride effects on central dopaminergic mechanisms in Parkinson's disease.

Effects of the long term, continuous administration of a dopamine agonist on motor response complications attending levodopa therapy were studied in 7 patients with advanced Parkinson's disease under controlled conditions. After a 3-month round-the-clock infusion of lisuride, the duration of antiparkinsonian action of levodopa increased by approximately 90%, and the therapeutic window for the acutely administered dopamine precursor widened by > 300%. These benefits were more than three times greater than those produced by 9 days of continuous levodopa administration. In contrast to the effects on levodopa pharmacodynamics, the continuous infusion of lisuride did not prolong its action, suggesting a lisuride effect on presynaptic as well as postsynaptic dopaminergic mechanisms. These results lend further support to the view that continuous dopamine replacement ameliorates motor fluctuations and peak-dose dyskinesias that complicate standard levodopa regimens. Our findings further suggest that alterations at both presynaptic and postsynaptic levels contributing to these motor complications tend to normalize with the more physiological stimulation afforded by continuous replacement strategies, especially when given chronically.     

Effectiveness of Madopar HBS plus Madopar standard in patients with fluctuating Parkinson's disease: two years of follow-up

Clinical response to a new galenic formulation of levodopa plus benserazide, Madopar HBS, was studied in 25 fluctuating parkinsonians. This open study was planned in two phases. In the first phase, the administering of HBS alone resulted in a surprisingly high number of dropouts. In the second phase, Madopar standard in association with Madopar HBS, the follow-up period was 24 months. A stable long-lasting improvement in predictable fluctuations and their severity was maintained for the whole period without any change in drug dose. Nocturnal and early morning akinesia improved too. The study shows that Madopar HBS plus Madopar standard is effective in producing a prolonged and stable response in parkinsonian fluctuating patients.     

Enantiomeric composition of urinary salsolinol in Parkinsonian patients after Madopar

Summary Urinary salsolinol output had been shown to be lower in Parkinsonian patients than in controls and to increase largely after L-dopa therapy. It had also been established that the R enantiomer of salsolinol is either the predominant or the sole enantiomer present in the urine of healthy subjects.When Madopar was administered to Parkinsonians, the enantiomeric composition of urinary salsolinol showed an S/R ratio around 1. Considering brain and plasma concentrations in dopamine, acetaldehyde and pyruvate, it is suggested that, under physiological conditions, urinary salsolinol should have a central origin in humans. Conversely, urinary salsolinol in Madopar-treated Parkinsonian patients might be predominantly formed at the periphery.