L Dopa/peripheral decarboxylase inhibitors Flashcards
1
Q
What are the generic and brand names of L Dopa/peripheral decarboxylase inhibitors?
A
- Levadopa, benserazide hydrochloride (Madopar)
* Levodopa, carbidopa (Sinemet)
2
Q
What is the method of action of L Dopa/peripheral decarboxylase inhibitors?
A
- In Parkinson’s, there is ↓ of dopamine in the nigrostriatal pathway (links the substantia nigra in the midbrain to the corpus striatum in the basal ganglia)
- = ↑ inhibitory effects on the thalamus
- = ↓ excitatory input to the motor cortex
- = Parkinson symptoms – bradykinesia, rigidity etc.
- L-dopa is a precursor of dopamine that can enter the brain via a membrane transporter
- Should always be given with a peripheral dopa-decarboxylase inhibitor (carbidopa) to ↓ conversion to dopamine outside the brain
3
Q
What are the indications for L Dopa/peripheral decarboxylase inhibitors?
A
- Early Parkinson’s disease (though dopamine agonists are preferred)
- Late Parkinson’s disease (preferred management)
- Secondary parkinsonism
4
Q
What are the contraindications of L Dopa/peripheral decarboxylase inhibitors?
A
- Elderly
- Existing cognitive/psychiatric diseases – causes confusion/hallucinations
- Cardiovascular disease - ↑ of hypotension
5
Q
What are the side effects of L Dopa/peripheral decarboxylase inhibitors?
A
- Nausea
- Drowsiness
- Confusion
- Hallucinations
- Hypotension
- Wearing off effect – symptoms worsen after duration of therapy increases
- = dyskinesias (involuntary movements)
6
Q
What are the interactions with L Dopa/peripheral decarboxylase inhibitors?
A
- Anti-pyschotics – contradictory effects on dopamine receptors
- Metoclopramide – contradictory effects on dopamine receptors
7
Q
What organ eliminates L Dopa/peripheral decarboxylase inhibitors?
A
Kidneys
8
Q
What information should be given to a patient taking L Dopa/peripheral decarboxylase inhibitors?
A
- Timing of the doses are important – make sure that they are stuck to the same time each day
- Never stop therapy straight away
