L Dopa/ Peripheral Decarboxylase Inhibitor Flashcards Preview

Year 3 Drugs - Neurological > L Dopa/ Peripheral Decarboxylase Inhibitor > Flashcards

Flashcards in L Dopa/ Peripheral Decarboxylase Inhibitor Deck (21):
1

Name two common L Dopa/ Peipheral Decarboxylase Inhbirots?

Sinemet and Madopar

2

What is Sinemet made up from?

Levo Dopa and Carbidopa

3

What is Madopar bade up of?

Levo Dopa and Benserazide

4

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.
= Parkinsons

5

Name some common features of Parkinson?

Bradykinesia and Rigidity

6

How does Levo Dopa work?

Levo dopa is a precursor to dopamine. It is broken down to dopamine by the enzyme dopa decarboxylase.

7

What enzyme is responsible for the breakdown of levo dopa to dopamine?

Dopa decarboxylase

8

Why can't you give dopamine as the treatment for Parkinson's?

Cannot pass the BBB

9

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

10

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.

11

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

12

What are the contra-indications for using Levodopa?

Pregnancy

13

When should Levodopa be used with caution

Elderly
Psyciatric disorders
Cognitive disorders e.g. Alzheimers as can aggravate confusion and hallucinations
CV disease as can cause hypotension and arrhythmias

14

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)

15

What are the side effects of Levodopa?

Nausea
Confusion/Drowsiness
Hypotension
Hallucinations
Wearing off effect

16

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

17

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

18

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.

19

Why should levodopa never be stopped suddenly?

There is a deterioration in symptoms and the risk of neuroleptic malignant syndrome

20

What is neuroleptic malignant syndrome?

A side effect of suddenly coming of levodopa causing life-threatening:
- fever
- altered mental status
- muscle rigidity
- autonomic dysfunction

21

What is a side effect of dopamine present outside the BBB?

Nausea