Dopamine agonists in parkinsonism

• for most patients dopamine agonists are used as second line therapy in Parkinson's disease. Some clinicians will use dopamine agonists as first line treatment in fit, young patients with Parkinson's disease (PD) but '..Opinion is divided as to whether newly diagnosed patients should receive levodopa, or a dopamine agonist, as their initial therapy (1)'
• NICE (2) state that it is not possible to identify a universal first-choice drug therapy for people with early PD
  • a dopamine agonist is a possible first-choice therapy for people with early PD
  • a dopamine agonist should be titrated to a clinically efficacious dose. If side effects prevent this, another agonist or a drug from another class should be used in its place
  • if an ergot-derived dopamine agonist is used, the patient should have a minimum of renal function tests, erythrocyte sedimentation rate (ESR) and chest radiograph performed before starting treatment, and annually thereafter
  • on view of the monitoring required with ergot-derived dopamine agonists, a non-ergot-derived agonist should be preferred in most cases
    
    
• dopamine agonists generally have a longer half life than L-dopa and may help with patients who suffer with "on-off" phenomena and dyskinesias
  
  
• side effects are common and hence only a minority of patients being controlled with dopamine agonist monotherapy
  • side effects of dopamine agonists include:
    • nausea, vomiting
    • dizziness
    • increased dyskinesias
    • neuropsychiatric complications
      
      
• dopamine agonists may be used to reduce motor fluctuations in people with later PD (2)

Reference:

1. MeReC Bulletin (1999); 10 (10): 37-40.
2. NICE (June 2006). Parkinson's disease