Early idiopathic parkinsonism: initiation and optimization of treatment.
Once a diagnosis of idiopathic parkinsonism has been made, the choice and timing of therapy depend almost entirely on the patient's need for symptomatic relief, as no presently available therapy has any effect on the pathogenesis of the disease. Five categories of drugs are available for the treatment of idiopathic parkinsonism. Anticholinergic agents are effective against tremor but have prominent adverse effects. Amantadine has similar effects but is more active against rigidity and bradykinesia. Selegiline is a monoamine oxidase-B inhibitor; once thought to affect the pathogenesis of idiopathic parkinsonism, it is now known to offer only symptomatic relief. The dopamine agonists (bromocriptine, pergolide, and lisuride) stimulate D2 receptors; they have antiparkinsonian effects and tolerance profiles broadly similar to those of levodopa but are slightly less efficacious. Pleural effusions and pulmonary fibrosis are unusual but important complications of these drugs; chest x-ray examinations are therefore recommended for all patients starting such treatment. Levodopa (combined with an extracerebral decarboxylase inhibitor to prevent nausea, the main adverse effect) has become the standard antiparkinsonism treatment. Patients using this preparation can suffer considerable variations in mobility and dyskinesia, which may be related to rapid, large-scale oscillations in plasma levodopa concentrations. Controlled-release (CR) preparations have been developed in an attempt to minimize these fluctuations and reduce long-term side effects. There is no universally agreed treatment for idiopathic parkinsonism. However, experience shows that a good balance of antiparkinsonian activity and adverse effects can be obtained by initiating treatment with a combination of levodopa and a decarboxylase inhibitor. A dopamine agonist can be added if the disease progresses and increased therapeutic activity is required.
Calne
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Neurodegenerative Disorders Centre, University of British Colúmbia, Vancouver, Canada.
D000547:Amantadine / Q000627:therapeutic use; D018680:Cholinergic Antagonists / Q000627:therapeutic use; D018491:Dopamine Agonists / Q000627:therapeutic use; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D010300:Parkinson Disease / Q000175:diagnosis / Q000188:drug therapy*; D012642:Selegiline / Q000627:therapeutic use
D018680:Cholinergic Antagonists; D018491:Dopamine Agonists; D012642:Selegiline; D007980:Levodopa; D000547:Amantadine