dopaminergic drugs for parkinson's disease

Question 1

disease state of parkinson’s disease

Answer 1

• deficiency of dopamine in the nigrostriatal pathway
• generates symptoms of parkinson’s such as :
  -> bradykinesia
  -> rigidity
  it is not possible to give dopamine itself because it does not cross the blood brain barrier

Question 2

adverse effects of dopaminergic drugs

Answer 2

• nausea
• drowsiness
• confusuon
• hallucinations
• hypotension

Question 3

major problem of levodopa

Answer 3

• wearing off effect
• patient’s symptoms worsen towards end of dosage interval
• this generates the opposite effect: excessive and involuntary movemente (dyskinesias)
• on off effect

Question 4

warnings for dopaminergic drugs for parkinson’s disease

Answer 4

• elderly
• those with existing cognitive or psychiatric disorders - due to risk of hallucinations
• cardiovascular disease due to the risk of hypotension

Question 5

why is levodopa always given with a peripheral dopa decarboxylase inhibitor (eg carbidopa)

Answer 5

(as co careldopa)
- reduces the conversion to dopamine outside of the brain
- this desirable interaction reduces nausea and lowers the dose needed for therapeutic effect

Question 6

interactions for dopaminergic drugs

Answer 6

• antipsychotics (particularly first generation)
• metoclopramide
• due to effects on dopamine receptors are contradictory