Parkinson's Disease

Question 1

Side effects of Dopamine agonists

Answer 1

e.g. Rotigotine

Impulse control disorder: gambling, hypersexuality, binge eating

Question 2

Parkinson Plus Syndromes

Name them and their classic features

Answer 2

Progressive supranuclear palsy - includes vertical gaze palsy.

Multiple system atrophy - includes early autonomic clinical features such as: postural hypotension, incontinence, and impotence.

Cortico-basal degeneration - includes involves spontaneous activity by an affected limb, or akinetic rigidity of that limb.

Lewy body dementia - includes fluctuations in cognitive impairment and visual hallucinations, often before parkinsonian features occur.

Question 3

Types of parkinson’s medical treatment

Answer 3

Synthetic Dopamine

DopamineAgonist

COMT inhibitors

MAO B inhibitors

Question 4

Synthetic dopamine

Answer 4

Levodopa

This is synthetic dopamine given orally to boost their own dopamine levels. It is usually combined with a drug that stops levodopa being broken down in the body before it gets the chance to enter the brain. These are PERIPHERAL DECARBOXYLASE INHIBITORS. Examples are carbidopa and benserazide.

Combination drugs are:

• Co-benyldopa (levodopa and benserazide)
• Co-careldopa (levodopa and carbidopa)

Levodopa is the most effective treatment for symptoms but becomes less effective over time. It is often reserved for when other treatments are not managing to control symptoms.

Question 5

Levodopa side effect

Answer 5

The main side effect of dopamine is when the dose is too high patients develop dyskinesias. Theses are abnormal movements associated with excessive motor activity. Examples are:

• Dystonia: This is where excessive muscle contraction leads to abnormal postures or exaggerated movements.
• Chorea: These are abnormal involuntary movements that can be jerking and random.
• Athetosis: These are involuntary twisting or writhing movements usually in the fingers, hands or feet.

Question 6

COMT inhibitors

e.g.

Pharmacology

Answer 6

e.g. entacapone

These are inhibitors of catechol-o-methyltransferase (COMT).

The COMT enzyme metabolises levodopa in both the body and brain.

Entacapone is taken with levodopa (and a decarboxylase inhibitor) to slow breakdown of the levodopa in the brain. It extends the effective duration of the levodopa.

Question 7

Dopamine Agnoist

Example

Context usually used in

Side effect

Answer 7

These mimic dopamine in the basal ganglia and stimulate the dopamine receptors.

They are less effective than levodopa in reducing symptoms.

They are usually used to delay the use of levodopa and are then used in combination with levodopa to reduce the dose of levodopa that is required to control symptoms.

One notable side effect with prolonged use is pulmonary fibrosis.

Examples are:

Bromocryptine
Pergolide
Carbergoline

Question 8

MAO B inhibitors

method of action

Context used in

Examples

Answer 8

Monoamine oxidase enzymes break down neurotransmitters such as dopamine, serotonin and adrenaline.

The monoamine oxidase-B enzyme is more specific to dopamine and does not act on serotonin or adrenalin.

These medications block this enzyme and therefore help increase the circulating dopamine.

Similarly to dopamine agonists, they are usually used to delay the use of levodopa and then in combination with levodopa to reduce the required dose.

Examples are:

• Selegiline
• Rasagiline

Question 9

What is the difference between parkinson’s disease and parkinsonism?

Answer 9

Parkinson’s Disease tends to be asymmetrical / unilateral