Parkinsons Flashcards
What is the difference between L-DOPA and dopamine?
L-dopa is a dopamine pre-cursor that can cross the blood brain barrier, and be converted by DOPA decarboxylase to dopamine.
How much oral L-DOPA reaches the brain?
1%
What is a contraindication for L-DOPA?
Closed angle glaucoma
Where does L-DOPA need to replenish dopamine in order to control parkinsons symptoms?
The neostriatum
What are ADRs of L-DOPA, MAOIs and Dopamine Receptor Agonists?
Schizophrenic-type psychosis symptoms, hypotension, dyskinesia.
What is the oral bioavailability of L-DOPA?
10%
What is a DDI of L-DOPA?
Vitamin B6, which incrases peripheral L-DOPA breakdown.
What drugs are given with L-DOPA?
Sinemet or madopar, which are peripheral DOPA decarboxylase inhibitors which decrease ADRs and increase effectiveness.
Name 3 examples of oral Dopamine Receptor Agonists
Bromocriptine, Ropinirole and Pergolide
Name an example of a sub-cutaneous Dopamine Receptor Agonist
Apomorphine
What is the mechanism of action of Dopamine Receptor Agonists?
Bind and agonise D2 dopamine receptors in the neostriatum.
Name a Monoamine Oxidase Type B Inhibitor used in treatment of Parkinsons
Selegiline
How does selegiline work?
Inhibits MAOb enzyme which breaksdown dopamine.
Name a Catechol-o-methyl Transferase Inhibitor and state when it would be used
Entacapone, and used to as an L-DOPA adjuvant to lower the required dose of L-DOPA and decrease it’s ADRs
Name 2 common ADRs of Catechol-o-Methyl Transferase Inhibitors
Abdominal pain and diarrhoea
What is a contraindication of entacapone use?
Phaeochromocytoma
How does entacapone work?
Inhibits Catechol-O-Methyl Transferase, which is an enzyme that breaks down dopamine.
Name some anticholinergics used in Parkinsons treatment
Benzatropine, Procyclidine, Orphenadrine
How do anticholinergics reduce Parkinsons symptoms?
Antagonise muscarinic receptors which are responsible for mediating striatum cholinergic excitation/activity.
What are ADRs of anticholinergics?
Memory loss, episodes of acute confusion, dry mouth and blurred vision.
What will happen if anticholinergics are rapidly withheld?
Worsening of Parkinsons
How does Amantidine work?
Stimulates neuronal dopamine release and inhibits it’s reuptake, as well as having some mild muscarinic antagonism, reducing striatum cholinergic activity.
What are some ADRs of Amantidine?
Anorexia, nausea and hallucinations.
How long is amantidine effective for in reducing Parkinsons symptoms?
6 months
