Parkinsons

Question 1

What is the difference between L-DOPA and dopamine?

Answer 1

L-dopa is a dopamine pre-cursor that can cross the blood brain barrier, and be converted by DOPA decarboxylase to dopamine.

Question 2

How much oral L-DOPA reaches the brain?

Answer 2

1%

Question 3

What is a contraindication for L-DOPA?

Answer 3

Closed angle glaucoma

Question 4

Where does L-DOPA need to replenish dopamine in order to control parkinsons symptoms?

Answer 4

The neostriatum

Question 5

What are ADRs of L-DOPA, MAOIs and Dopamine Receptor Agonists?

Answer 5

Schizophrenic-type psychosis symptoms, hypotension, dyskinesia.

Question 6

What is the oral bioavailability of L-DOPA?

Answer 6

10%

Question 7

What is a DDI of L-DOPA?

Answer 7

Vitamin B6, which incrases peripheral L-DOPA breakdown.

Question 8

What drugs are given with L-DOPA?

Answer 8

Sinemet or madopar, which are peripheral DOPA decarboxylase inhibitors which decrease ADRs and increase effectiveness.

Question 9

Name 3 examples of oral Dopamine Receptor Agonists

Answer 9

Bromocriptine, Ropinirole and Pergolide

Question 10

Name an example of a sub-cutaneous Dopamine Receptor Agonist

Answer 10

Apomorphine

Question 11

What is the mechanism of action of Dopamine Receptor Agonists?

Answer 11

Bind and agonise D2 dopamine receptors in the neostriatum.

Question 12

Name a Monoamine Oxidase Type B Inhibitor used in treatment of Parkinsons

Answer 12

Selegiline

Question 13

How does selegiline work?

Answer 13

Inhibits MAOb enzyme which breaksdown dopamine.

Question 14

Name a Catechol-o-methyl Transferase Inhibitor and state when it would be used

Answer 14

Entacapone, and used to as an L-DOPA adjuvant to lower the required dose of L-DOPA and decrease it’s ADRs

Question 15

Name 2 common ADRs of Catechol-o-Methyl Transferase Inhibitors

Answer 15

Abdominal pain and diarrhoea

Question 16

What is a contraindication of entacapone use?

Answer 16

Phaeochromocytoma

Question 17

How does entacapone work?

Answer 17

Inhibits Catechol-O-Methyl Transferase, which is an enzyme that breaks down dopamine.

Question 18

Name some anticholinergics used in Parkinsons treatment

Answer 18

Benzatropine, Procyclidine, Orphenadrine

Question 19

How do anticholinergics reduce Parkinsons symptoms?

Answer 19

Antagonise muscarinic receptors which are responsible for mediating striatum cholinergic excitation/activity.

Question 20

What are ADRs of anticholinergics?

Answer 20

Memory loss, episodes of acute confusion, dry mouth and blurred vision.

Question 21

What will happen if anticholinergics are rapidly withheld?

Answer 21

Worsening of Parkinsons

Question 22

How does Amantidine work?

Answer 22

Stimulates neuronal dopamine release and inhibits it’s reuptake, as well as having some mild muscarinic antagonism, reducing striatum cholinergic activity.

Question 23

What are some ADRs of Amantidine?

Answer 23

Anorexia, nausea and hallucinations.

Question 24

How long is amantidine effective for in reducing Parkinsons symptoms?

Answer 24

6 months