Levodopa-induced dyskinesia in Parkinson's disease: epidemiology, etiology, and treatment.
ABSTRACT Although levodopa is the gold standard for treating motor symptoms of Parkinson's disease (PD), long-term therapy leads to levodopa-induced dyskinesia (LID). Dyskinesia refers to involuntary movements other than tremor and most commonly consists of chorea that occurs when levodopa-derived dopamine is peaking in the brain ("peak-dose dyskinesia"). However, dyskinesia can also consist of dystonia or myoclonus and occur during other parts of the levodopa dosing cycle. New validated rating scales and home diaries can better help the health care provider assess the timing and severity of dyskinesia. The exact etiology of LID is unknown, but there is evidence that abnormal pulsatile stimulation of dopamine receptors may be contributory. Treatment of LID includes adjustment of PD medications to maximize "on" time without troublesome dyskinesia. Amantadine is the only medication available with demonstrated ability to reduce the expression of established LID without reducing antiparkinsonian benefit. Other medications that are currently being studied to treat established LID include antiepileptics and serotonergic medications. Deep brain stimulation of the subthalamic nucleus is now the most commonly used surgical procedure for PD patients, and it is very effective in treating LID.
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ABSTRACT: Pramipexole has been a widely used dopamine agonist for the last decade. Recently an extended release formulation of pramipexole has been introduced as both monotherapy for patients with early Parkinson's disease as well as for patients with more advanced disease, as an adjunct to L-DOPA. Along with the enhanced patient compliance seen with once a day dosing, there are other potential advantages of extended release preparations of dopamine agonists. Patients initiated on pramipexole have a lower incidence of developing motor fluctuations including dyskinesia than those initiated on L-DOPA. Pramipexole requires a prolonged dose titration compared to L-DOPA, and generally does not have the efficacy of L-DOPA. The extended release form of pramipexole shows comparable mean and peak serum levels with once a day dosing as seen with three times a day dosing of the immediate release preparation. The extended release preparation has been studied in randomized multicenter clinical trial against both placebo and the immediate release preparation in the setting of early Parkinson's disease as monotherapy and in more advanced patients with motor fluctuations on L-DOPA. In both settings the extended release preparation was superior to placebo and comparable to the immediate release form in efficacy with a similar side effect profile including nausea, sleepiness, leg edema, dyskinesias, hallucinations and impulse control disorders.Journal of central nervous system disease. 01/2011; 3:169-78.
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ABSTRACT: Spontaneous involuntary dystonic and choreatic movements induced by L-DOPA (L-DOPA-induced dyskinesias (LID)) represent a severe complication of long-time pharmacotherapy in Parkinson's disease that deserves novel therapeutics. Previous studies demonstrated antidyskinetics effect of the KV7.2-7.5 channel opener retigabine after acute and chronic treatment in a rat model of LID. We hypothesized that this effect was mainly mediated by KV7.2/3 channels located on striatal projection neurons, as an increased activity of these neurons seems to be involved in the pathophysiology of LID. We therefore examined the acute effects of the KV7.2/3 preferring channel opener ICA 27243 (N-(6-Chloro-pyridin-3-yl)-3,4-difluoro-benzamide, 5-15mg/kg i.p.) on LID in this animal model. Ten and 15mg ICA 27243 significantly reduced abnormal involuntary movements (AIM) while no negative impact on the antiparkinsonian effect of L-DOPA was observed. However, at the end of the testing session (180min) AIM scores increased after application of both doses. Further studies have to clarify if this can be avoided by a different application regime. Nevertheless, the present results suggest that selective openers of KV7.2/3 channels might be interesting candidates for the treatment of LID as antidyskinetic effects occurred at well tolerated doses and did not interfere with the antiparkinsonian effect of L-DOPA.Neuroscience Letters 04/2013; · 2.03 Impact Factor
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ABSTRACT: Background The mechanisms underlying neurotoxicity caused by L-DOPA are not yet completely known. Based on recent findings, we speculated that the increased expression of divalent metal transporter 1 without iron-response element (DMT1−IRE) induced by L-DOPA might play a critical role in the development of L-DOPA neurotoxicity. To test this hypothesis, we investigated the effects of astrocyte-conditioned medium (ACM) and siRNA DMT-IRE on L-DOPA neurotoxicity in cortical neurons.Methods and FindingsWe demonstrated that neurons treated with L-DOPA have a significant dose-dependent decrease in neuronal viability (MTT Assay) and increase in iron content (using a graphite furnace atomic absorption spectrophotometer), DMT1−IRE expression (Western blot analysis) and ferrous iron (55Fe(II)) uptake. Neurons incubated in ACM with or without L-DOPA had no significant differences in their morphology, Hoechst-33342 staining or viability. Also, ACM significantly inhibited the effects of L-DOPA on neuronal iron content as well as DMT1−IRE expression. In addition, we demonstrated that infection of neurons with siRNA DMT-IRE led to a significant decrease in DMT1−IRE expression as well as L-DOPA neurotoxicity.Conclusion The up-regulation of DMT1−IRE and the increase in DMT1−IRE-mediated iron influx play a key role in L-DOPA neurotoxicity in cortical neurons.PLoS ONE 01/2009; 4(2). · 3.53 Impact Factor