Avoid postponing treatment. It should be commenced as soon as symptoms interfere with working capacity or the patient's enjoyment of life. This will be apparent only if the correct questions are asked as the patient may accept impaired enjoyment without appreciating that it is due to Parkinson's disease. Start low, e.g. Sinemet 100/25 tab bd). The dosage should be tailored so that the patient neither develops side effects nor is on an inadequate dose of medication without significant therapeutic benefit (Table 29.5).
The older drugs such as anticholinergics and amantadine have minimal usage in modern management as levodopa, which basically counters bradykinesia, is the best drug and the baseline of treatment. With the onset of disability (motor disturbances) levodopa in combination with a decarboxylase inhibitor (carbidopa or benserazide) in a 4:1 ratio should be introduced. Levodopa therapy does not significantly improve tremor but improves rigidity, dyskinesia and gait disorder. Consider benzhexol or benztropine if tremor is the feature.
Pergolide can be used in treatment, especially with the levodopa 'on-off phenomenon (fluctuations throughout the day). It appears to be most effective when used in combination. The major side effects of pergolide are similar to levodopa. Dyskinesia and nausea are less problematic but severe psychiatric disturbances are more common with bromocriptine. It should therefore be used with caution in patients with a history of confusion or dementia. Selegiline promises to be an effective first-line drug. If there is associated pain, depression or insomnia, the tricyclic agents, e.g. amitriptyline, can be effective.
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