Neurology

Question 1

What is the dopaminergic drug used in parkinsons disease? Which drug is routinely given with it to reduce side effects?

Answer 1

Levodopa
Carbidopa (extracerebral decarboxylase inhibitor)

Question 2

What are the side effects of levodopa? Why?

Answer 2

Nausea and vomiting - CTZ stimulation
Psychiatric (hallucinations, delusions, confusion, vivid dreams) - mesolimbic/mesocortical stimulation
Postural hypotension
Dyskinesia - extra dopamine at peak of drug concentration

Question 3

What is dyskinesia?

Answer 3

Unwanted movements

Question 4

What problems occur with long term levodopa therapy?

Answer 4

Return of akinesia
Shortened duration of action (end of dose deterioration)
Sudden drop in action (on / off effect)
Dyskinesia

Question 5

What drugs are used in young patients with parkinsons? Example. Why?

Answer 5

Dopamine agonists, eg. Bromocriptine
To delay starting levodopa and thus extend time before long term levodopa complications like on/off and end of dose deterioration

Question 6

Examples and what is the role of MAOb inhibitors in parkinsons

Answer 6

Selegilinie
Potentiates levodopa allowing dose reduction in late disease
Mild action when used alone in early disease and may delay need for levodopa.

Question 7

Example and role of COMT inhibitor in parkinsons

Answer 7

Entacapone

Prolongs elimination of levodopa reducing off time in late disease

Question 8

Examples of MAOI and COMT inhibitors. Which can be used alone in parkinsons

Answer 8

Selegiline MAOI - can be used alone

Entacapone - COMT - cant be used alone

Question 9

What is the role of antimuscarinics in parkinsons? When are they least and most useful?
Example
How do they work?

Answer 9

Help improve in early stages but not great with akinesia
Most useful in drug induced parkinsonism
Procyclidine
Post synaptic neurones have inhibitory d2 receptors and excitatory muscarinic receptors so if dopamine is low same effect can be gained by blocking muscarinic

Question 10

Example and side effects of antimuscarinics used in parkinsons

Answer 10

Dry mouth, urinary retention, constipation, hallucinations,

Procyclidine

Question 11

What classes of drug therapy are available for parkinsons disease?

Answer 11

Dopaminergic drugs 
Peripheral dopa decarboxalase inhibitor 
Dopamine agonists
Dopamine releaser 
MAOb inhibitor 
COMT inhibitor 
Antimuscarinic