No established disease modifying or neuroprotective therapy presently exists.
There is no evidence that delaying levodopa or dopaminergic therapy has any benefit or that levodopa is toxic.
The initiation of medications occur when patients experience functional impairment or social embarrassment from their disease symptomatology.
If the disease and motor symptoms are mild but require therapy, an initial monoamine oxidase type B inhibitor such a selegiline or rasagiline may be tried before moving to more potent treatments such as a dopamine agonist or levodopa.
In early Parkinson’s disease a small symptomatic benefit is demonstrated by monoamine oxidase type B inhibitors.
Anti-cholinergic medications a more effective than placebo in improving motor functions in PD, but their benefits for tremor are inconclusive.
Beta blockers such as propranolol may improve parkinsonian tremor and motor function.
Clozapine improves Parkinson’s disease tremor.
Amantadine results for efficacy is not clear
For more seriously impaired PD patients levodopa or a dopamine agonist is administered.
Trials demonstrate levodopa provides the greatest symptomatic benefit.
Levodopa associated with fewer side effects such as edema, somnolence, impulse control disorders, freezing and hallucinations than dopamine agonists.
Dopamine agonists are have fewer dopaminergic motor complications of dyskinesia than levodopa.
Dopamine agonists usually initiated in individuals younger than 60 years since dyskinesia more common in younger patients.
The early advantage of dopamine agonists over levodopa decreases over time.