Dopamine and dopamine agonists (DAs) at the synapse

Dopamine agonists play a major role in the treatment of PD.¹ They act by directly stimulating intact postsynaptic receptors in the brain linked to motor control.¹ Although they tend to be less potent than levodopa in reducing parkinsonian motor symptoms, dopamine agonists are much less likely to cause dyskinesias.¹ This characteristic can make dopamine agonists a useful tool for the management of early and fluctuating PD.¹

Dopamine agonists have several key advantages over levodopa: they tend to have a longer half-life, which allows for a more prolonged action; their absorption in the gut is not inhibited by dietary protein; and they are easily absorbed across the blood–brain barrier.¹ Dopamine agonists may therefore allow the patient to reduce their levodopa usage without worsening their parkinsonian symptoms.²

COMT=catechol-O-methyltransferase; DA=dopamine agonist; MAO-A=monoamine oxidase type A; PD=Parkinson’s disease