Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of selegiline (L-deprenyl) on plasma catecholamines, clinical response, and drug tolerability was studied in 13 patients with Parkinson's disease (PD) treated with L-Dopa/benserazide and entacapone, a peripheral catechol-O-methyltransferase (COMT) inhibitor, in a placebo-controlled double-blind study. An L-Dopa test was performed on 3 study days. The first study day was with L-Dopa/benserazide only (control), the second after 14 days of treatment with 200 mg entacapone taken concomitantly with L-Dopa/benserazide in combination with either selegiline (10 mg daily) or placebo. After a 2-week washout period, selegiline and placebo treatments were switched, and the third study day was after 14 days of treatment. During the study days, clinical response was evaluated at 30-min intervals for 6 h, by using the motor score of the Unified Parkinson's Disease Rating Scale (UPDRS). In addition, repeated blood pressure measurements were made, and plasma samples were taken for analysis of L-Dopa, 3-O-methyldopa (3-OMD), dihydroxyphenyl acetic acid (DOPAC), homovanillic acid (HVA), dopamine, noradrenaline, and 3-methoxy-4-hydroxyphenylethylene glycol (MHPG). Monoamine oxidase B (MAO-B) and COMT enzyme activities were measured from platelets and erythrocytes, respectively. Entacapone improved the clinical response to L-Dopa during both selegiline and placebo (p < 0.001) treatments. The improvement was more marked during combined selegiline and entacapone treatment than with entacapone alone (p < 0.01). Entacapone significantly increased plasma L-Dopa and DOPAC levels and decreased plasma 3-OMD and MHPG levels both with selegiline and placebo. Selegiline partially inhibited the entacapone-induced increase of plasma DOPAC. Plasma dopamine and noradrenaline levels did not change. Entacapone decreased erythrocyte COMT activity by > 35% (p < 0.001), and platelet MAO-B activity was almost completely inhibited by selegiline (p < 0.001). One patient withdrew because of diarrhea, dizziness, and loss of sleep when receiving selegiline treatment. Otherwise no differences in adverse events, mean daily blood pressures, or other safety parameters were observed between selegiline and placebo treatments. Our results suggest that entacapone can be safely administered together with L-Dopa and selegiline in patients with PD, although further studies with larger number of patients and longer treatment periods are necessary to confirm this finding.
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PMID:Simultaneous MAO-B and COMT inhibition in L-Dopa-treated patients with Parkinson's disease. 925 Oct 66

Tolcapone is a potent, reversible catechol-O-methyltransferase (COMT) inhibitor with both peripheral and central activity. It has been demonstrated to improve motor function and allow levodopa dose reductions in Parkinson's disease (PD) patients who are experiencing either a stable response or motor fluctuations while on levodopa/dopa decarboxylase inhibitor therapy. Because striatal dopamine is metabolized by COMT and monoamine oxidase (MAO), central COMT inhibition alone or in combination with MAO inhibition might provide symptomatic benefit for patients not receiving levodopa. We conducted a pilot study to evaluate the tolerability, safety, and efficacy of tolcapone alone and in combination with oral selegiline in early untreated PD patients. Patients were randomized to receive 200 mg tolcapone three times a day or placebo for the 8 weeks of the study. Open-label oral selegiline (5 mg in the morning and midday) was administered to all patients during the second 4 weeks of the study. There was no difference between treatment groups according to the investigator's assessment of tolerability at week 4. Ninety-five percent of tolcapone-treated patients and 98% of placebo-treated patients experienced excellent or good tolerability during the first 4 weeks (95% confidence interval [CI]: -10.3, 5.7; p = 0.57). A decrease in tolerability occurred in the tolcapone group during the second 4 weeks of the study following the addition of selegiline. The most commonly reported side effects were diarrhea (31% tolcapone, 7% placebo), nausea (21% tolcapone, 2% placebo), urine discoloration (12% tolcapone, 0% placebo), dizziness (12% tolcapone, 5% placebo), headaches (12% tolcapone, 10% placebo), and abdominal pain (10% tolcapone, 5% placebo). We did not identify symptomatic benefit associated with tolcapone alone or in combination with oral selegiline in this group of otherwise untreated PD patients.
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PMID:A pilot evaluation of the tolerability, safety, and efficacy of tolcapone alone and in combination with oral selegiline in untreated Parkinson's disease patients. Tolcapone De Novo Study Group. 968 68

The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, and dosage and administration of tolcapone are reviewed. Tolcapone is the first drug brought to market from the new class of selective and reversible inhibitors of catechol-O-methyltransferase. Tolcapone is indicated for use in the treatment of Parkinson's disease as an adjunct to levodopa-carbidopa therapy in patients who are experiencing fluctuations in symptoms and who are not responding to or are not appropriate candidates for other adjunctive therapies. The absolute bioavailability of tolcapone after an oral dose is about 65%. Clinical trials have demonstrated that tolcapone 50-200 mg three times daily reduces "off" time in patients refractory to levodopa-carbidopa, Unified Parkinson's Disease Rating Scale scores, and the dosage of levodopa-carbidopa required for symptom suppression. The most frequent adverse effects of tolcapone are dyskinesia, nausea, sleep disorders, dystonia, orthostatic hypotension, diarrhea, dizziness, and hallucinations; also, there is a potential for elevation of liver transaminase concentrations in the blood. To date, three deaths from fulminant hepatic failure in association with tolcapone have been reported. Extensive liver function testing is required of all patients before and during therapy. The recommended starting dosage is 100 mg orally three times daily as an adjunct to levodopacarbidopa therapy; a concurrent reduction in the levodopa dosage of about 30% is suggested. Patient response should be monitored carefully during the first three weeks of therapy; treatment should be discontinued in patients failing to respond during this initial use. Tolcapone is of benefit in fluctuating Parkinson's disease, but benefits must be carefully weighed against risks in individual patients.
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PMID:Tolcapone: a novel approach to Parkinson's disease. 1056 98

Both the catechol-O-methyltransferase (COMT) inhibitor entacapone and the monoamine oxidase B (MAO-B) inhibitor selegiline are L-dopa extenders. Both are used, often simultaneously, as adjuncts to L-dopa/dopa decarboxylase (DDC) inhibitor treatment of Parkinson's disease (PD). Their possible interactions have not been previously studied in a double-blind manner.We studied clinical response, tolerability, haemodynamics and cardiac rhythm in 16 PD patients with end-of-dose-type motor fluctuations. The patients' individual L-dopa/DDC inhibitor treatment was stabilized before the experimental treatments. This was followed by three consecutive, randomized, double-blind 2-week treatment periods with entacapone (200mg with each L-dopa dose), selegiline (10mg o.d.) or both entacapone and selegiline with the L-dopa/DDC inhibitor medication. Clinical efficacy (L-dopa test with repeated motor and dyskinesia scoring) and safety (orthostatic test, 24-h ambulatory ECG, haematological and clinical chemistry variables and adverse events) evaluations were performed before each treatment (control) and at the end of each treatment period.All three treatments, entacapone, selegiline, and entacapone+selegiline as adjunct to L-dopa/DDC inhibitor improved (p<0.05) clinical disability compared to L-dopa only but they did not differ significantly from each other. Dyskinesias increased with all the treatments, statistically significantly (p<0.01) with entacapone+selegiline. No significant differences in haemodynamics were observed between control and any of the experimental treatments, or between the experimental treatments in the orthostatic test. One patient already had symptomatic orthostatism before experimental treatments (control). In two other patients orthostatism emerged after the introduction of selegiline, and in one after every experimental treatment. Twenty-four-hour ECG did not show any differences in supraventricular or ventricular extrasystoles or heart rate between treatments. No statistically significant differences were observed in adverse events or in haematology and clinical chemistry variables. One patient treated with entacapone+selegiline discontinued the study due to dizziness and insomnia. Our results suggest that co-administration of entacapone with L-dopa/DDC inhibitor, with or without selegiline, improves clinical disability, is safe, but may also enhance dopamine-related adverse events to some extent in PD patients with end-of-dose type motor fluctuations.
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PMID:Entacapone and selegiline with L-dopa in patients with Parkinson's disease: an interaction study. 1090 Mar 96

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.
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PMID:The tolerability and efficacy of entacapone over 3 years in patients with Parkinson's disease. 1260 88

Levodopa, a dopamine precursor administered with a decarboxylase inhibitor, is the principal therapy for treating the symptoms of Parkinson's disease. Unfortunately, after approximately 2-5 years, it frequently loses its beneficial effects as evidenced by motor fluctuations. Entacapone (Comtan) is a selective, reversible catechol-O-methyltransferase inhibitor that dose-dependently increases the peripheral bioavailability of levodopa and prolongs its duration of action. Early studies confirmed that treatment with entacapone resulted in increased striatal uptake of levodopa after iv. administration of [18F] levodopa. Preclinical studies confirmed decreased formation of COMT-dependent metabolites, including 3-O methyldopa and homovanillic acid. Clinical studies performed in patients with motor fluctuations have shown that entacapone prolonged the duration of motor response by an average of 1-1.3 h. Parkinsonian patients receiving therapeutic doses of dopamine agonists and selegiline also experienced an incremental improvement in 'on' time when entacapone was added to their drug regimen. At present, there are no published safety studies beyond six to twelve months in duration, or studies in nonfluctuating patients. Based on the clinical trial data available, entacapone is well-tolerated in the majority of patients. Dopaminergic-related adverse effects include dyskinesias, nausea and dizziness. Non-dopaminergic adverse effects include diarrhoea, abdominal discomfort and discoloration of urine. Diarrhoea is occasionally severe and may require discontinuation of therapy. Of 406 entacapone-treated subjects, there was one incidence of elevated liver transaminases, although this was attributed to an underlying disorder. In the US, Phase III trials have been completed and a New Drug Application (NDA) has been filed. In Europe, the drug received a favourable review and is currently available.
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PMID:Entacapone, a catechol-O-methyltransferase inhibitor for treating Parkinson's disease: review and current status. 1599 91