Flashcards in L Dopa/ Peripheral Decarboxylase Inhibitor Deck (21):
Name two common L Dopa/ Peipheral Decarboxylase Inhbirots?
Sinemet and Madopar
What is Sinemet made up from?
Levo Dopa and Carbidopa
What is Madopar bade up of?
Levo Dopa and Benserazide
What is the pathology behind Parkinson's?
Lack of dopamine in the niagastriatal pathway. This is the pathway between the substantial nigira (midbrain) to the Corpus Striatum (basal ganglia). This lack of dopamine causes the basal ganglia to have a greater inhibitory input to the thalamus and reduced the excitatory input to the midbrain.
Name some common features of Parkinson?
Bradykinesia and Rigidity
How does Levo Dopa work?
Levo dopa is a precursor to dopamine. It is broken down to dopamine by the enzyme dopa decarboxylase.
What enzyme is responsible for the breakdown of levo dopa to dopamine?
Why can't you give dopamine as the treatment for Parkinson's?
Cannot pass the BBB
How do you stop Levo Dopa being broken down before it crosses the BBB?
Give it with a peripheral decarboxylase inhibitor e.g. carbidopa and bensarazide
What are dopamine agonists used for? and examples
Often given before treatment with levo dopa
Ropinirole and pramipexol - selective agonists for the D2 receptor, which predominates in the striatum.
What are the common indications for using Levodopa?
1. Early Parkinson's: dopamine agonists usually preferred
2. Late Parkinson's
3. Idiopathic Parkinson's: e.g. parkinsoninism linked to other drugs not idiopathic
What are the contra-indications for using Levodopa?
When should Levodopa be used with caution
Cognitive disorders e.g. Alzheimers as can aggravate confusion and hallucinations
CV disease as can cause hypotension and arrhythmias
What are the common interactions with Levo dopa?
Blood pressure medications (aggravates low bp)
Metoclopramide (opposite dopamine effects)
Antipsychotics (opposite dopamine effects)
Monoamine oxidase inhibitors (risk of hypertension crisis)
What are the side effects of Levodopa?
Wearing off effect
What is the wearing off effect?
Patients symptoms worsen towards the end of a dosage interval
Gets worse the longer a patient has been on the treatment
How can you overcome the wearing off effect?
Increasing the dose and frequency of the medication but this can generate the opposite effects causing involuntary movements (dyskinesias) at the beginning of the dosage interval
What is the on-off effect?
Going from worsening symptoms of bradykikesias and rigidity at the end of a treatment cycle to the opposite effects e.g. dyskinesias at the beginning of the next cycle.
Why should levodopa never be stopped suddenly?
There is a deterioration in symptoms and the risk of neuroleptic malignant syndrome
What is neuroleptic malignant syndrome?
A side effect of suddenly coming of levodopa causing life-threatening:
- altered mental status
- muscle rigidity
- autonomic dysfunction