Parkinsons - Dopaminergic drugs

Question 1

What is the mechanism of action of levodopa used for parkinsonism?

Answer 1

Treatment seeks to increase dopaminergic stimulation to the striatum. It is not possible to give dopamine itself because it does not cross the blood–brain barrier. By contrast, levodopa (l-dopa) is a precursor of dopamine that can enter the brain via a membrane transporter

Question 2

What is the primary pathological issue in parkinsons disease?

Answer 2

Deficiency of dopamine in the nigrostriatal pathway that links the substantia nigra in the midbrain to the corpus striatum in the basal ganglia - > this causes the basal ganglia to exert greater inhibitory effects on the thalamus, which in turn reduces excitatory input to the motor cortec

Question 3

What are important adverse side effects of levodopa used in parkinsons disease?

Answer 3

• Nausea
• Vomiting
• Drowsiness
• Confusion
• Hallucinations
• Hypotension
• Psychosis

Question 4

What is levodopa always given with?

Answer 4

Carbidopa

Question 5

What needs to be monitored in all patients receiving dopaminergic therapy for parkinsons?

Answer 5

BP

Question 6

What is important when dealing patients on dopaminergic drugs ?

Answer 6

Timings of the doses - ask exactly when they take them

Question 7

Why should you never stop dopaminergic drugs abruptly?

Answer 7

Risk precipitating neuroleptic malignant syndrome

Question 8

In patients who are unable to take dopaminergic drugs orally, how could you administer dopaminergic medication?

Answer 8

Transdermal preparation

Question 9

How is levodopa taken?

Answer 9

3-4 times daily tablet taken with food

Question 10

What contraindication would you want to check for in someone you are starting on levodopa?

Answer 10

Glaucoma