PARKINSON'S: COMTi

Question 1

COMT inhibitors

Answer 1

Inhibits catechol-O-methyltransferase.
Prevents peripheral breakdown of levodopa = more levodopa reaches the brain

Question 2

Catechol-O-methyltransferase

Answer 2

Enzyme that degrades catecholamines (dopamine, adrenaline + noradrenaline)

Question 3

When are they used?

Answer 3

Adjunct to levodopa in “end of dose” motor fluctuations.

Question 4

Examples

Answer 4

Entacapone
Tolcapone
Opicapone

Question 5

Side effects

Answer 5

1. Dyskinesias
2. N&V
3. Hepatoxicity (especially with tolcapone)
   - patients should be counseled on how to recognise liver disorders e.g. N&V, fatigue, abdominal pain, dark urine
4. Urine reddish browh (entacapone)

Question 6

Dyskinesia

Answer 6

• Involuntary movement of the body, the head can shake side to side
• Usually, a side effect of levodopa and occurs when other symptoms of Parkinson’s (e.g. rigidity, tremor and bradykinesia) are controlled

Question 7

Interactions - increased CV (sympathomimetic) effects

Answer 7

Adrenaline
Noradrenaline
MAOIs e.g. tranylcypromine

Question 8

Which COMT inhibitor is preferred over the other and why?

Answer 8

Entacapone is more preferred over Tolcapone
Because of hepatoxicity associated with tolcapone

Question 9

What is Stalevo?

Answer 9

Levodopa + Carbidopa
AND
Entacapone