Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0030567 (Parkinson's disease)
 63,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Over the last six years, eight new substances for the treatment of idiopathic parkinsonism (IP) have been approved for use: four oral and one parenteral dopamine agonist (apomorphine), two COMT-inhibitors and budipine. The old drug amantadine has experienced a renaissance in the treatment of a complication occurring during long-term treatment of IP, namely levodopa-induced dyskinesia. Deep brain stimulation with programmable pulse generators and stereotactically implanted electrodes are increasingly being used in patients with severe on-off phases and levodopa dyskinesia. The treatment of Parkinson's disease unresponsive to dopaminergic substances and that associated with dementia remains problematical. In combinations of parkinsonism and dementia, the cholinesterase inhibitors are being used in particular for Lewy body dementia.
 ...
PMID:[Dopaminergic agents, COMT inhibitors or amantadine? Proper treatment for your Parkinson patient]. 1207 Aug 48

Catechol-O-methyltransferase (COMT; E.C. 2.1.1.6) is a ubiquitous enzyme in nature that plays an important role in the metabolism of catechol neurotransmitters and xenobiotics. In particular, inactivation of drugs such as L-3,4-dihydroxyphenylalanine (L-DOPA) via O-methylation is of relevant pharmacological importance, because L-DOPA is currently the most effective drug used in the treatment of Parkinson's disease. This justified the interest in developing COMT inhibitors as potential adjuncts to L-DOPA therapy. The kinetics of inhibition by BIA 3-335 (1-[3,4-dihydroxy-5-nitrophenyl]-3-(N-3'-trifluormethylphenyl)-piperazine-1-propanone dihydrochloride) were characterized using recombinant rat soluble COMT. BIA 3-335 was found to act as a potent, reversible, tight-binding inhibitor of COMT with a K(i) of 6.0 +/- 1.6 nM and displaying a competitive inhibition toward the substrate binding site and uncompetitive inhibition toward the S-adenosyl-L-methionine (SAM) binding site. The 2.0-A resolution crystal structure of COMT in complex with its cosubstrate SAM and a novel inhibitor BIA 3-335 shows the atomic interactions between the important residues at the active site and the inhibitor. This is the first report of a three-dimensional structure determination of COMT complexed with a potent, reversible, and tight-binding inhibitor that is expected to have therapeutic applications.
 ...
PMID:Kinetics and crystal structure of catechol-o-methyltransferase complex with co-substrate and a novel inhibitor with potential therapeutic application. 1223 26

During the last few decades, there has been a remarkable progress in our understanding of the biology of Parkinson's disease (PD), which has been translated into the development of numerous antiparkinsonian drugs. There are different therapeutic strategies for patients in an early stage versus patients in a late stage of the disease. The current therapeutic arsenal includes levodopa preparations, MAO-B inhibitors, dopamine agonists, COMT inhibitors and several other compounds that target non-dopaminergic systems. Much interest is focused on the potential neuroprotective effect of the already available drugs, as well as on new research approaches for the development of disease-modifying agents. These include mainly anti-glutamategic compounds, anti-apoptotic and antioxidative agents. Future therapy might include targeted delivery of trophic factors or genes involved in the pathogenesis of the disease. Apart from the classic levodopa-associated motor complications, such as dyskinesias and response fluctuations and psychosis, many other problems of advanced disease should be focused upon and solved including fatigue, freezing of gait, postural instability, depression, anxiety and panic attacks, sleep disturbances, autonomic dysfunction and sensory complaints.
 ...
PMID:New drugs in the future treatment of Parkinson's disease. 1237 61

Catechol-O-methyltransferase (COMT, EC 2.1.1.6) plays a central role in the metabolic inactivation of neurotransmitters and neuroactive xenobiotics possessing a catechol motif. 1-(3,4-Dihydroxy-5-nitrophenyl)-2-phenyl-ethanone (BIA 3-202) is a novel nitrocatechol-type inhibitor of COMT, the potential clinical benefit of which is currently being evaluated in the treatment of Parkinson's disease. In the present work we characterize the molecular interactions of BIA 3-202 within the active site of COMT and discuss their implication on the regioselectivity of metabolic O-methylation. Unrestrained flexible-docking simulations suggest that the solution structure of this complex is better described as an ensemble of alternative binding modes, in contrast to the well defined bound configuration revealed by the X-ray structures of related nitrocatechol inhibitors, co-crystallized with COMT. The docking results wherein presented are well supported by experimental evidence, where the pattern of in vitro enzymatic O-methylation and O-demethylation reactions are analyzed. We propose a plausible explanation for the paradoxical in vivo regioselectivity of O-methylation of BIA 3-202, as well as of its related COMT inhibitor tolcapone. Both compounds undergo in vivo O-methylation by COMT at either meta or para catechol hydroxyl groups. However, results herein presented suggest that, in a subsequent step, the p-O-methyl derivatives are selectively demethylated by a microsomal enzyme system. The overall balance is the accumulation of the m-O-methylated metabolites over the para-regioisomers. The implications for the general recognition of nitrocatechol-type inhibitors by COMT and the regioselectivity of their metabolic O-methylation are discussed.
 ...
PMID:Molecular modeling and metabolic studies of the interaction of catechol-O-methyltransferase and a new nitrocatechol inhibitor. 1258 50

Parkinson's disease is one of the most common neurodegenerative disorders affecting large majority of population who are older than age of 65. Apart from dopamine, acetylcholine and glutamate, adenosinc has also been identified in the basal ganglia. Adenosine modulates the release of a variety of neurotransmitters including dopamine. In order to establish adenosine-dopamine interactions in drug-induced catatonia we studied the effect of adenosine in drug-induced catatonia in mice. In the present study adenosine dose dependently produced catatonia when assessed on rota-rod and bar tests in mice. Adenosine also potentiated the catatonic effect of perphenazine. L-dopa plus carbidopa or OR-486 (a potent centrally acting COMT inhibitor) completely reversed adenosine-induced catatonia. Since reversal by scopolamine of adenosine-induced catatonia was not to the same extent as with l-dopa and OR-486 it appears that catecholamines particularly dopamine rather than cholinergic modulation is more important in adenosine induced catatonia. The motor dysfunction (catatonia) could be easily assessed using rota-rod test apparatus in mice.
 ...
PMID:Role of adenosine in drug-induced catatonia in mice. 1259 16

The symptoms of Parkinson's disease can become increasingly difficult to control as the disease advances, particularly with the development of motor complications, such as end-of-dose wearing-off and dyskinesias, following long-term therapy. At this stage, the patient is frequently referred to a Parkinson's disease specialist for advice on the management of their disease. In this review we provide an overview of the Parkinson's disease specialist's strategies for coping with such problems. This includes strategy to prevent or delay motor fluctuations and the concept of the long duration response. The paper also includes establishing the optimum and most rational levodopa treatment schedule, improving levodopa absorption, use of COMT-inhibition, the addition of oral dopaminergic agonists, and the use of subcutaneous injections or infusions of apomorphine or lisuride. Finally, we highlight the increasing importance of treatment strategies that stimulate dopamine receptors in a more continuous, less pulsatile manner as a way of reducing the risk of developing treatment-associated motor complications.
 ...
PMID:Prevention and treatment of motor fluctuations. 1291 71

More than 30 years after its development, levodopa is still the most effective treatment for the symptomatic control of Parkinson's disease (PD). Although a number of therapies have been developed in an attempt to improve PD management, such as dopaminergic agonists and inhibitors of COMT and MAO-B, most patients still depend on levodopa alone because of its superior ability to control PD symptoms. The issue of toxicity has been raised by in vitro studies suggesting that levodopa might be toxic to dopaminergic neurons, but this has since been answered by in vivo studies finding no evidence of toxicity and possibly even neurotrophic-like effects. A more pressing concern regarding levodopa is its association with the development of motor complications after long-term use. Pulsatile dopaminergic stimulation as a result of erratic absorption and the short half-life of levodopa have been central issues in attempts to explain this occurrence. Evidence suggests that altering the delivery of levodopa to provide a more continuous supply of this drug to the brain may result in improved control of PD symptoms.
 ...
PMID:New developments in levodopa therapy. 1471 76

Current concepts suggest that avoidance of pulsatile stimulation of dopamine receptors in Parkinson's disease (PD) can prevent the onset of dyskinesia. In MPTP-treated primates, repeated administration of levodopa or other short-acting dopamine agonist drugs leads to the onset of marked involuntary movements. In contrast, treatment with long-acting dopamine agonists leads to a much lower level of dyskinesia. Similar results have been obtained in PD patients, although the introduction of levodopa is a requirement in virtually all patients and this leads to further increases in motor complications. The concept of continuous dopaminergic stimulation should also apply to levodopa, such that reduced dyskinesia would be expected if it could be administered in a manner that avoids pulsatile receptor stimulation. In MPTP monkeys, administration of multiple small doses of levodopa in conjunction with the peripheral COMT inhibitor entacapone removes much of the pulsatility of motor function seen with standard levodopa treatment regimens and, at the same time, results in a lower incidence and intensity of dyskinesia. Furthermore, the addition of multiple small doses of levodopa plus entacapone to dopamine agonist treatment also avoids dyskinesia induction in MPTP-treated primates. These results suggest that administering of levodopa with entacapone as either initial or supplemental therapy for PD patients might reduce the risk for motor complications. Clinical trials to assess this hypothesis and determine if the results in MPTP monkeys can be duplicated in PD patients are warranted.
 ...
PMID:Avoidance of dyskinesia: preclinical evidence for continuous dopaminergic stimulation. 1471 80

The aim of this trial was to evaluate the effects of the COMT inhibitor entacapone on both the pharmacokinetic profile and clinical efficacy of controlled release levodopa in Parkinson's disease (PD) patients. Twelve PD patients experiencing "end-of-dose" type motor fluctuations were evaluated in this single-blind, randomized cross-over study. A single dose of either entacapone (200 mg) or placebo was co-administered with controlled release levodopa. Blood samples were taken every 30 minutes for 3 hours, and in 6 patients, sampling was continued for a further 3 hours. The clinical response to treatment was evaluated using the Unified Parkinson's Disease Rating Scale motor score. Addition of entacapone to levodopa treatment prolonged the "on" phase of the PD patients by 37% (p<0.05). This increased duration of 'on' time was concomitant with a significant increase in levodopa bioavailability (AUC). These data confirm the ability of entacapone to enhance the clinical efficacy of controlled release levodopa formulations, and provide further evidence that entacapone is of value in extending the benefits of levodopa in PD patients experiencing motor fluctuations.
 ...
PMID:Entacapone improves the pharmacokinetic and therapeutic response of controlled release levodopa/carbidopa in Parkinson's patients. 1476 20

Motor fluctuations in Parkinson's disease (PD) typically develop after 4-6 years of therapy, and affect approximately half of all patients. The wearing-off effect is the most common type, and "delayed-on," "no-on," and "on-off" effects, as well as dyskinesias, may also develop as the disease progresses. Collectively, motor fluctuations represent a significant source of disability in advanced PD patients, and their mitigation is a major goal of patient management. Adjunctive medications, including dopamine agonists, amantadine, MAO-B inhibitors, and COMT inhibitors, each may reduce the frequency or duration of "off" periods, but none does so completely, and each contributes its own side effects which may limit optimal dosing. Surgery is another strategy to reduce "off" time, and both pallidotomy and deep brain stimulation of the globus pallidus or the subthalamic nucleus have been shown to be highly effective in this regard. However, surgery may be contraindicated in elderly advanced patients who could most benefit from its effect on "off" time. The unmet need for treatment of "off" episodes suggests the potential utility of an agent such as apomorphine injectable, which can reliably trigger an "on" response within 10-15 minutes of injection.
 ...
PMID:Management of motor complications in Parkinson's disease. 1503 64


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>