Dopaminergic drugs for Parkinson disease

At a glance

• Parkinson disease motor signs are classically said to appear after roughly half or more of nigral dopaminergic neurons and about 70% to 80% of striatal dopamine are lost (estimates vary between studies). Every drug here replaces dopamine, slows its breakdown or mimics it.
• Levodopa is the most effective drug. Its short half-life and the loss of presynaptic storage explain motor fluctuations and dyskinesia.
• Dopamine agonists last longer but cause more impulse control disorders, somnolence, oedema and hallucinations.