tolcapone and Dyskinesia--Drug-Induced

Combining levodopa with the catechol-O-methyltransferase (COMT) inhibitor entacapone has been shown to be an effective strategy in the management of Parkinson's disease (PD) patients experiencing motor fluctuations. Safety and tolerability information has come from postmarketing surveillance studies as well as several randomized, placebo-controlled trials with long-term open-label extension phases specifically investigating the safety and tolerability of levodopa plus entacapone. Results show the most common dopaminergic side effects to be dyskinesia and nausea, which result from the increased bioavailability of levodopa and can be readily managed. Non-dopaminergic side effects include diarrhea and harmless urine discoloration. There is no convincing evidence of hepatic injury with entacapone use, and therefore monitoring of liver enzymes is unnecessary. With over 300,000 patient-years of exposure, levodopa combined with entacapone can be considered safe and well tolerated.

Topics: Aged; Antiparkinson Agents; Benzophenones; Catechol O-Methyltransferase Inhibitors; Catechols; Clinical Trials as Topic; Dyskinesia, Drug-Induced; Enzyme Inhibitors; Female; Humans; Liver; Male; Nausea; Nitriles; Nitrophenols; Parkinson Disease; Safety; Tolcapone

Parkinson disease progression is associated with the development of levodopa short-duration responses and dyskinesias, as well as gait freezing. Levodopa dose adjustment and adjunctive treatment with dopamine agonists form the major therapeutic strategies. Catechol O-methyltransferase inhibitors are also appropriate considerations, whereas other drugs, including selegiline, amantadine, anticholinergic agents, and propranolol, have a more minor role.

Topics: Amantadine; Antiparkinson Agents; Benzophenones; Carbidopa; Catechol O-Methyltransferase Inhibitors; Catechols; Cholinergic Antagonists; Dopamine Agonists; Dose-Response Relationship, Drug; Drug Combinations; Dyskinesia, Drug-Induced; Enzyme Inhibitors; Humans; Levodopa; Nitriles; Nitrophenols; Parkinson Disease, Secondary; Propranolol; Randomized Controlled Trials as Topic; Selegiline; Tolcapone

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 Cmax or tmax 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.

Topics: Benzophenones; Catechol O-Methyltransferase; Catechols; Dose-Response Relationship, Drug; Dyskinesia, Drug-Induced; Enzyme Inhibitors; Humans; Levodopa; Nitriles; Nitrophenols; Parkinson Disease; Tolcapone

Tolcapone is a potent, selective, reversible inhibitor of COMT. Coadministration of tolcapone with levodopa and a decarboxylase inhibitor prolongs the elimination half-life of levodopa and reduces the formation of 3-0-metildopa in a dose-dependent form. The improvement in the pharmacokinetics of levodopa prolongs the motor effects of levodopa. Clinical studies have shown that the concomitant administration of levodopa and tolcapone is effective on the management of the wearing-off phenomenon. Tolcapone can significantly reduce the off time and increases the total on time while simultaneously reducing levodopa dosage and frequency. Most adverse events are dopaminergic in nature and related to the increase in levodopa bioavailability. Dyskinesias may increase in frequency and severity in patients already having dyskinesias and these may appear for the first time after adding tolcapone in patients at risk. Diarrhoea is the main nondopaminergic adverse event leading to the stop of the drug in less than 10% of cases. Taking into account that tolcapone significantly enhance the action of levodopa, it would be wise to reduce the total daily dose of levodopa at the same time that tolcapone is introduced. No tolerance effect was observed in 12-month studies. Tolcapone can be used with standard or sustained release levodopa, and, when appropriate, in conjunction with dopamine agonists or selegiline.

Topics: Antiparkinson Agents; Benzophenones; Dose-Response Relationship, Drug; Double-Blind Method; Drug Synergism; Drug Therapy, Combination; Dyskinesia, Drug-Induced; Humans; Levodopa; Nitrophenols; Parkinson Disease; Tolcapone; Treatment Outcome

More than 50% of patients with Parkinson's disease develop motor response fluctuations (the 'wearing off" phenomenon) after more than five years of levodopa therapy. Inhibition of catechol-O-methyltransferase by tolcapone has been shown to increase levodopa bioavailability and plasma elimination half life, thereby prolonging the efficacy of levodopa.. The primary objective was to evaluate the efficacy of tolcapone in reducing "wearing off" in levodopa treated, fluctuating parkinsonian patients. Secondary objectives included assessment of reduction in levodopa requirements, improvement in patients' clinical status, duration of improvements, and tolerability of tolcapone.. In this multicentre, randomised, double blind, placebo controlled trial, 58 patients received placebo, 60 received 100 mg tolcapone three times daily (tid), and 59 received 200 mg tolcapone tid, in addition to levodopa/benserazide.. After three months with 200 mg tolcapone tid, "off" time decreased by 26.2% of the baseline value, "on" time increased by 20.6% (p < 0.01 vs. placebo), and the mean total daily levodopa dose decreased by 122 mg from the baseline dose of 676 mg (p < 0.01). These responses were maintained up to nine months. With 100 mg tolcapone tid, "off" time decreased by 31.5% (p < 0.05), "on" time increased by 21.3% (p < 0.01), and the mean total daily levodopa dose decreased by 109 mg from the baseline dose of 668 mg (p < 0.05). With 200 mg tolcapone tid, unified Parkinson's disease rating scale motor and total scores were significantly reduced, and quality of life (sickness impact profile) scores were significantly improved. Both dosages were well tolerated. Dyskinesia was the most often reported levodopa induced adverse event. Diarrhoea was the most often reported non-dopaminergic adverse event and the most frequent reason for withdrawal from the study: four patients in the 100 mg tolcapone tid group and six in the 200 mg tid group withdrew because of diarrhoea.. Tolcapone prolongs "on" time in fluctuating parkinsonian patients while allowing a reduction in daily levodopa dosage, thereby improving the efficacy of long term levodopa therapy.

Topics: Aged; Antiparkinson Agents; Benserazide; Benzophenones; Catechol O-Methyltransferase Inhibitors; Diarrhea; Dopamine Agents; Double-Blind Method; Drug Administration Schedule; Drug Therapy, Combination; Dyskinesia, Drug-Induced; Enzyme Inhibitors; Europe; Female; Humans; Levodopa; Male; Middle Aged; Nitrophenols; Parkinson Disease; Tolcapone; Treatment Outcome

Forty patients affected by severe Parkinson's disease (PD) were treated with tolcapone as an adjunctive therapy to L-DOPA, for 3-7 months, until this drug was discontinued because of side-effects (2 diarrhoea, one of them with orthostatic hypotension, 2 increments of liver enzymes) or because of mandatory indications of the European drugs authority. All patients, after 3-6 months of L-DOPA therapy adjustments, received entacapone for 3 months again followed by withdrawal. L-DOPA daily dosage was significantly reduced by tolcapone and entacapone (p = 0.01 and 0.05). "On" time was increased by 15% during tolcapone treatment (p < 0.05), and by 8% during entacapone treatment. "Off" time was decreased by 16% during tolcapone and by 7% during entacapone treatment. Entacapone was withdrawn in the same patient who experienced diarrhoea and orthostatic hypotension during tolcapone because of recurrence of side-effects, in 6 patients because of increment of dyskinesias (with hallucinations) and in 1 patients because of rhythmic, jerking myoclonus.

Topics: Aged; Antiparkinson Agents; Benzophenones; Catechols; Drug Therapy, Combination; Dyskinesia, Drug-Induced; Female; Humans; Levodopa; Male; Mental Disorders; Middle Aged; Nitriles; Nitrophenols; Parkinson Disease; Substance Withdrawal Syndrome; Tolcapone

Topics: Aged; Antiparkinson Agents; Benzophenones; Catechol O-Methyltransferase Inhibitors; Confusion; Drug Interactions; Dyskinesia, Drug-Induced; Enzyme Inhibitors; Humans; Levodopa; Nitrophenols; Parkinson Disease; Tolcapone