Dyskinesia refers to an impairment of voluntary movement. The resultant tics and other movements are often referred to as dyskinesias. Dyskinesia is sometimes caused by long-term use of anti-psychotic drugs or other dopamine antagonists like the antiemeticmetoclopramide. The effect of these drugs can be tardive, meaning the dyskinesia continues or appears even after the drugs are no longer taken (see Tardive dyskinesia). The term antipsychotic is applied to a group of drugs used to treat psychosis. ... A dopamine antagonist is a drug which serves the purpose of blocking dopamine receptors in the brain. ... An antiemetic is a drug that is effective against vomiting and nausea. ... Metoclopramide (INN) (IPA: ) is a potent dopamine receptor antagonist used for its antiemetic and prokinetic properties. ... Tardive dyskinesia is a serious neurological disorder caused by the long-term and/or high-dose use of dopamine antagonists, usually antipsychotics and among them especially the typical antipsychotics. ...
In context of Parkinson's disease, dyskinesias are often the result of chronic levodopa (L-dopa) therapy. These motor fluctuations occur in more than half of PD patients after 5 to 10 years of levodopa therapy, with the percentage of affected patients increasing over time.[Obeso JA, et al. The evolution and origin of motor complications in Parkinson's disease. Neurology. 2000;55(suppl 4):S13-S20.]
Dyskinesias most commonly occur at the time of peak L-dopa plasma concentrations and are thus referred to as peak-dose dyskinesias. As patients advance, they may evidence diphasic dyskinesias, which occur when the drug concentration rises or falls.
The use of MDMA (ecstasy) has been shown to enhance the effects of L-Dopa while reducing the associated dyskinesia in patients with Parkinson's disease [1].
References
^ Iravani, M., Jackson, M., Kuoppaaki, M., Smith, L. & Jenner, P. (2003). 3,4-Methylenedioxymethamphetamine (Ecstasy) Inhibits Dyskinesia Expression and Normalizes Motor Activity in 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine-Treated Primates, Journal of Neuroscience, 23, 9107–9115
Tardive dyskinesia is a serious neurological disorder caused by the long-term and/or high-dose use of dopamine antagonists, usually antipsychotics and among them especially the typical antipsychotics.
The cause of tardive dyskinesia appears to be related to damage to the system that uses and processes the neurotransmitter dopamine.
There is no known cure for tardive dyskinesia, but preliminary research suggests that the atypical neuroleptic clozapine (Clozaril®) may improve the state of the patient.
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