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.     

Controlled-release levodopa/benserazide (Madopar HBS): clinical observations and levodopa and dopamine plasma concentrations in fluctuating parkinsonian patients

Summary In five levodopa (l-dopa)-treated patients with Parkinson's disease with severe fluctuations of motor performance, plasma l-dopa as well as dopamine levels were measured during 2 days, first under optimal standard l-dopa with peripheral decarboxylase inhibitor (PDI) and then after a dose adjustment period using slow-release l-dopa/benserazide (Madopar HBS) in an open inpatient trial. Three patients benefited from the slow-release preparation; two patients deteriorated with a tendency to have an unpredictable response, a delay to turn on with the first dose in the morning, as well as an increase in dyskinesia corresponding to l-dopa cumulation during the day. These problems were subsequently also seen during the follow-up period of 1 year in those patients who benefited from Madopar HBS as inpatients. This might indicate that patient compliance is more difficult with the new formulation. After 1 year all patients had returned to their previous standard l-dopa/PDI treatment. l-Dopa levels continued to fluctuate, but to a lesser degree with Madopar HBS. The equivalent l-dopa dosage had to be increased by 56% (29–100%) with Madopar HBS while mean dopamine levels increased in four patients (by 47–257%) without the occurrence of peripheral side-effects. This implies that with the new formulation more l-dopa is metabolized to dopamine and explains the necessity to increase the equivalent l-dopa dosage.     

COMT inhibition by tolcapone further improves levodopa pharmacokinetics when combined with a dual-release formulation of levodopa/benserazide. A novel principle in the treatment of Parkinson's disease.

The objective of the study reported here was the investigation of the effect of catechol-O-methyl transferase (COMT) inhibition by tolcapone on the pharmacokinetics of levodopa and 3-O-methyldopa (3-OMD) after administration of a new dual-release formulation (dual-RF) of levodopa/benserazide (200/50). The study had a double-blind, placebo-controlled, randomized, crossover design and was conducted in 18 healthy young subjects. On the 2 treatment days, separated by a washout period of 7 days, the dual-RF was administered in combination (blinded) with tolcapone (200 mg) or placebo. Both treatment combinations were well tolerated. Tolcapone increased the bioavailability (AUC 0-infinity) and apparent elimination half-life (t(1/2)) of levodopa by 80 and 40%, respectively, compared to placebo. The maximal plasma concentration (Cmax) was slightly elevated by tolcapone. In the presence of tolcapone, formation of 3-OMD was substantially reduced. In conclusion, the effect of tolcapone on levodopa pharmacokinetics after administration of the dual-RF is similar to the one observed after immediate- and slow-RFs and leads to a marked improvement in levodopa pharmacokinetics and subsequently to an optimization of levodopa therapy.     

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.     

The hydrosoluble fiber Plantago ovata husk improves levodopa (with carbidopa) bioavailability after repeated administration

The influence of treatment duration (7 or 14 days) with Plantago ovata husk/levodopa/carbidopa in the bioavailability and other pharmacokinetic parameters of levodopa were evaluated in rabbits. Fiber was administered at two different doses, 100 and 400 mg/kg, and the dosage of levodopa/carbidopa was 20:5 mg/kg. These doses were administered once a day. When 100 mg/kg of fiber was administered, the mean AUC value obtained for levodopa increased 20.2% from day 1 to day 7, and 27.2% from day 1 to day 14; C(max) was 8.6% higher on day 7 and 11.7% higher on day 14. When administering 400 mg/kg of fiber, the increase in AUC values was 17.6% on day 7 and 24.9% on day 14, and that of C(max) 11.1% on day 7 and 11.3% on day 14. The concentration determined immediately before drug administration (C(min)) increased progressively with the duration of treatment, and the highest increase (53.2%) was observed on day 14 with 100 mg/kg of fiber. There was also a delay in levodopa elimination (higher MRT and lower Cl) in a fiber-dose dependent manner. In summary, we found that there was an improvement in the extent of levodopa absorbed with higher final concentrations and that levodopa elimination was slower with the administration of P. ovata husk.     

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.     

Entacapone increases levodopa exposure and reduces plasma levodopa variability when used with Sinemet CR

Entacapone is a catechol-O-methyltransferase (COMT) inhibitor used as an adjunct to levodopa/dopa decarboxylase inhibitors in the treatment of Parkinson's disease. Entacapone increases the bioavailability and reduces the daily variation of plasma levodopa when administered with standard levodopa preparations. These parameters were studied when entacapone was administered with a controlled-release levodopa preparation after repeated administrations throughout the day in 16 healthy male volunteers. On 2 test days, 200 mg entacapone or placebo was administered 4 times during the day at 4-hour intervals concomitantly with a single dose of controlled-release levodopa/carbidopa 100 mg/25 mg (Sinemet CR). Plasma levodopa, 3-O-methyldopa (3-OMD), and carbidopa concentrations were measured before intake of the medication and then every 30 minutes for 16 hours (until midnight), and less frequently up to 24 hours after the first levodopa dose. The minimum, maximum, and average concentration of levodopa; the daily variation of levodopa concentration; and the area under the time concentration curve (AUC) were calculated. The mean (+/-SD) plasma levodopa AUC was 39% (P = 0.0001) higher with entacapone (11,802 +/- 1454 ng/hour/mL) compared with placebo (8465 +/- 927 ng/hour/mL). The daily variation of plasma levodopa was reduced by about 25% with entacapone (P < 0.01). Entacapone significantly reduced plasma 3-OMD concentration by about 50% (P = 0.0001), indicating marked COMT inhibiting activity. There were no differences in plasma carbidopa concentrations. Entacapone significantly increased the bioavailability of levodopa and reduced its daily variation when administered concomitantly with a controlled-release levodopa preparation.     

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.     

Entacapone in combination with standard or controlled-release levodopa/carbidopa: a clinical and pharmacokinetic study in patients with Parkinson's disease

We investigated clinical response and pharmacokinetics of levodopa when entacapone, a catechol O-methyltransferase (COMT) inhibitor, was administered concomitantly with either a standard (Std) or a controlled-release (CR) levodopa/carbidopa preparation to 12 patients with Parkinson's disease. An open cross-over study consisted of the initial study day without entacapone followed by two 10-day treatment periods with a study day at the end of each period. The patients who received entacapone (200 mg t.i.d. or q.i.d.) concomitantly with Std levodopa/carbidopa (200/50 mg t.i.d. or q.i.d.) during the first period received subsequently entacapone with CR levodopa/carbidopa (200/50 mg t.i.d. or q.i.d.), and vice versa. On the study days, the patients took the medication at 8 a.m. and the second dose 6 h later. We evaluated the disability before drug administration and then 1-h intervals for 8 h. Repeated blood samples were taken for analysis of plasma levodopa, 3-O-methyldopa (3-OMD), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), carbidopa, and entacapone. Entacapone decreased significantly the clinical disability with both Std and CR levodopa, slightly more with Std levodopa. The clinical response started earlier with Std levodopa whereas the “on”-time increased by about 1 h, equally with both levodopa preparations. Std levodopa produced 23% higher area under the curve (AUC) of levodopa than the CR preparation, but entacapone increased the AUC approximately equally, 33% with Std and 36% with CR levodopa. Entacapone slightly decreased C_max of levodopa in combination with Std levodopa, whereas it increased that with CR levodopa. The AUC of 3-OMD was about 20% smaller after Std than after CR levodopa. Entacapone decreased the AUC of 3-OMD by 38–40% with both levodopa preparations. Entacapone did not modify the AUC levels of carbidopa although its bioavailability was less from CR levodopa than from Std levodopa. In three patients levodopa dosage was reduced when on Std levodopa because of nausea. Otherwise, the treatments were well tolerated. The study shows that entacapone is an effective COMT inhibitor when combined with either Std levodopa or CR levodopa.     

Madopar HBS in fluctuating parkinsonian patients: two-year treatment

In an open-label study, we substituted conventional levodopa plus benserazide: 100/25 (Madopar) with a controlled-release form (HBS) in 18 fluctuating parkinsonian patients for 24 months. Significantly positive results were obtained in both peak-dose and diphasic dyskinesias up to 12 months of treatment; morning akinesias were also improved up to 6 months. A general trend of deterioration, compared to the first 3-6 months of HBS treatment, was observed in "off" fluctuations after 1 year: akinesias due to a delayed response worsened after 1 year of treatment also when compared with the conventional treatment. Positive results were obtained with new HBS on standard Madopar-related psychiatric disorders.     

Chronic levodopa therapy enhances dopa absorption: Contribution to wearing-off

Summary Effects of the chronic administration of levodopa on its peripheral pharmacokinetics and the contribution of the pharmacokinetics to the pathogenesis of the wearing-off phenomenon are re-evaluated. The concentration of plasma levodopa and clinical symptoms were determined 4 hours after oral levodopa (levodopa 100 mg+benserazide 25 mg) administration on 55 parkinsonian patients. Long-term levodopa therapy markedly increased the peak levodopa concentration (Cmax) and the area under the time-concentration curve (AUC); whereas, it decreased time to the peak concentration (Tmax) and the elimination half-life (T1/2). These results suggest that longterm levodopa therapy accelerates the absorption of levodopa. The wearingoff group (n=23), however, had a markedly higher Cmax and AUC, and a shorter Tmax and T1/2 than the stable group (n=32). We speculate that the clinical expression of stable or wearing-off depends on the absorption of levodopa as well as the presynaptic terminal and post synaptic receptors.     

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.     

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.     

Clinical significance of the relationship between O-methyldopa levels and levodopa intake

A recent clinical trial of controlled-release carbidopa/levodopa preparation afforded us the opportunity to examine the effects of chronically increasing circulating 3-O-methyldopa (OMD) levels on the clinical response to levodopa. In patients taking standard Sinemet, both mean plasma OMD levels and the area under the plasma concentration-versus-time curve (AUC) obtained during 8-hour periods of blood sampling correlated highly with the total daily intake of levodopa. In patients taking the controlled-release formulation, the mean daily intake of levodopa was doubled. This, in turn, led to a doubling of the mean OMD level and its AUC, whereas the AUC for levodopa was unchanged. Despite the increase in circulating OMD there was no reduction in mobility in either the "on" or "off" conditions. Thus, doubling plasma OMD levels did not seem to interfere with brain uptake of levodopa sufficiently to cause a deterioration in its therapeutic efficacy in these patients.     

Madopar HBS in Parkinson patients with nocturnal akinesia

Madopar Hydrodynamically Balanced System (HBS), a new sustained-release levodopa preparation, was used to control severe nightly disabilities in 15 outpatients suffering from Parkinson's disease in an advanced state and with long-term levodopa therapy. This medication was given ante noctem in addition to an otherwise unchanged daily regimen of levodopa administration. In 13 patients a considerable diminution in nocturnal akinesia and in the frequency of waking up was reached with a mean dosage of 308 mg of Madopar HBS. Early morning akinesia was only slightly alleviated in four patients. The nocturnal off-period pain disappeared in one patient. Adverse effects consisted of nocturnal dyskinesia in two patients and early morning dystonia in another two patients. The regular use of sleeping pills was clearly reduced after Madopar HBS therapy.     

A double-blind, cross-over trial with madopar HBS in patients with Parkinson's disease

Fourteen patients with Parkinson's disease and motor fluctuations were given 125 mg of Madopar HBS or placebo twice a day in addition to their optimal standard Madopar treatment in a double-blind, cross-over study. Clinical response was evaluated by the King's College Hospital Parkinson's Disease Rating Scale, the Mobility in Bed Scale and self-scoring diaries. A significant improvement with the drug was found according to the rating scales, whereas evaluation by self-scoring diaries showed no significant changes. In three patients we observed worsening of abnormal involuntary movements. The present trial suggests that a low dose of Madopar HBS can be useful in addition to levodopa therapy in some patients on long-term treatment.     

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.     

Increased dosage of carbidopa in parkinsonian patients on low carbidopa-levodopa regimen. Effect on levodopa bioavailability

The effect of a 2.5-fold increase in daily carbidopa intake on the bioavailability of levodopa was studied in six patients with Parkinson's disease on a low chronic regimen of carbidopa-levodopa (Sinemet) at the fixed ratio of 1:10. The extent of levodopa absorption, expressed as the area under the 11-h plasma levodopa concentration-time curve (AUC0-11 h), was not enhanced by the higher carbidopa dose. A significant increase in the AUC was found for the levodopa metabolite 3-O-methyldopa at the higher carbidopa intake. Clinical performances of individual patients were identical with both carbidopa-levodopa ratios. From these data, an adequate inhibition of peripheral decarboxylation and hence a good bioavailability of levodopa may be expected in patients taking low doses of carbidopa-levodopa, using currently available commercial preparations.     

Dispersible levodopa has a fast and more reproducible onset of action than the conventional preparation in Parkinson's disease. A study with optoelectronic movement analysis

In a crossover study we compared the single dose effect of 200 mg levodopa (plus decarboxylase inhibitor) in the form of Madopar with that of Madopar Dispersible on the motor performance of eight patients with Parkinson’s disease, after 12 h without their ordinary anti-parkinsonian medication and food intake. Objective recording of their performance was done with an opto-electronic camera and automatic computerised treatment of the movement data and with scoring according to the United Parkinson’s Disease Rating Scale. We conclude that Madopar Dispersible has a much faster and more constant onset of action than the standard preparation (25 vs 46 min.). The effect duration and the effects on motor performance were otherwise the same.     

Inhibition of the COMPT with entacapone in the treatment of motor fluctuations in Parkinson disease

Motor fluctuations are a common problem in the long-term treatment of Parkinson's disease (PD). Entacapone (Comtan) is a potent, peripherally acting, reversible and selective inhibitor of catechol-O-methyltransferase (COMT). Used as an adjuvant to levodopa therapy, entacapone slows the elimination of levodopa by decreasing peripheral conversion to 3-O-methyldopa, increasing central extracellular levodopa and striatal dopamine concentrations. Coadministered with levodopa/carbidopa or levodopa/benserazide, at doses of 200 mg 2 to 10 times daily in patients with end-of-dose fluctuations, entacapone may increase the duration of clinical response, both after the first single dose and after repeated dosing. At this dosage, it has a time to peak plasma concentration of 1.2 h and an elimination half life of 3.4 h. In two multicentric, long-term (24 weeks), parallel, randomized and placebo-controlled studies, entacapone increased the duration of 'on' time (by approximately 1 hour daily) and decreased the duration of 'off' time with a concomitant reduction in the mean daily levodopa dose. In these and other phase III studies, entacapone was generally well tolerated, with most adverse effects being dyskinesias and gastrointestinal disorders. Increased dyskinesia were generally controlled by reducing levodopa doses. Entacapone appears to be a useful adjunct in extending the benefit of each levodopa dose in PD patients with end-of-dose fluctuations.