Parkinsonism Drugs

Question 1

How does Parkinsonism generally arise?

Answer 1

• Degeneration of dopaminergic neurons in the basal ganglia, leading to a dopamine deficit
• Deficit in quantity of movement

Question 2

What are the possible pathways affected by a dopamine deficit?

Answer 2

1. Mesocortical / Mesolimbic pathways = Schizophrenia
2. Nigro-striatal pathways = Parkinsonism
3. Tubulo-infundibular pathways = Hyperprolactinaemia

Question 3

What are the treatment options for a dopamine deficit?

Answer 3

1. Dopamine agonists (e.g. rotigotine) are firstline for younger patients
2. L-DOPA is firstline for older patients
3. MAO / COMT inhibitor adjuncts
4. Symptomatic treatment

Question 4

What is L-DOPA?

Answer 4

• Precursor of dopamine that can cross BBB

Question 5

What converts L-DOPA to dopamine?

Answer 5

DOPA decarboxylase

Question 6

What is L-DOPA usually formulated with?

Answer 6

• Carbidopa / Benserazide
• Inhibit DOPA decarboxylase in the periphery, but do not cross BBB

Question 7

What are the five ST adverse effects of L-DOPA?

Answer 7

1. Nausea
2. Dyskinesia
3. Impulsive control disorders
4. Daytime sleepiness
5. Psychosis / Hallucinations

Question 8

What are the three LT effects of L-DOPA?

Answer 8

1. Dyskinesias
2. On-off phenomenon (brain unable to regulate dopamine well, leading to unpredictable fluctuations between good and poor mobility)
3. Freezing of gait (suddenly unable to move despite intention to do so)

Question 9

How do we mitigate LT effects of L-DOPA?

Answer 9

Continuous infusion