Parkinson's Drugs Flashcards
(28 cards)
Why does levodopa lose it’s effect later in the progression of Parkinson’s disease?
Taken up by dopaminergic neurones in the substantia nigra.
These neurones graduallt die off during the course of Parkinson’s, so can’t work with levodopa.
Why shouldn’t levodopa be taken with high-protein meals?
Competes for absorption with amino acids
What is the MoA of DOPA decarboxylase inhibitors?
Inhibit DOPA decarboxylase to reduce the conversion of levodopa to dopamine in the gut and peripheries.
Why are levodopa and DOPA decarboxylase inhibitors often prescribed together as one tablet?
Increases the amount of levodopa reaching the brain, and reduces systemic side effects of excess dopamine in the body
Name two drugs containing a combination of levodopa and DOPA decarboxylase inhibitor
- Co-careldopa (sinemet)
- Co-beneldopa (madopar)
What is ‘wearing off’?
When pts feel like they need another dose before thier next dose is due
State two motor and two systemic adverse effects of levodopa
- Wearing off
- Dyskinesia
- Spasms
- Freezing
- On/of
- Nausea and anorexia
- Dry mouth
- Hypotension, tachycardia
- Impulse control disorders,
- Paranoia, hallucinations
What effect does VitB6 have on levodopa?
Increases the peripheral breakdown
Name a monoamine oxidase (MAOI) type B inhibitor
Selegiline
Rasagaline
What is the mechanism of action of MAOI type B inhibitors?
Inhibits the breakdown of dopamine in the gut and the brain to increase the action of levodopa
MAOI type B inhibitors can be used alone to smooth the motor response
Name a COMT inhibitor
Entacapone
What is the MoA of COMT inhibitors?
Prevents the peripheral breakdown of dopamine to increase the duration of action of levodopa
Why are COMT inhibitors ineffective without levodopa?
Acts peripherally
Which three drug classes does Stalevo consist of?
Levodopa
DOPA decarboxylase inhibitor
COMT inhibitor
Name two dopamine receptor agonists and their administration routes
Rotigotine - patch
Apomorphine - SC
Ropinirole - tablet
Pramipexole - tablet
How do dopamine receptor antagonists compare to levodopa?
- Less effective
- Fewer motor complications
- Impulse control disorders e.g. pathological gambling, hypersexuality
- Hallucinations more common
- Sedation and confusion
Name an anticholinergic
Procyclidine
Orphenadrine
Trihexyphenidydyl
What are anticholinergics used for in Parkinson’s?
Tremor
What does deep brain stimulation involve?
Stimulation of the subthalamic nucleus
Used in pts who can’t tolerate levodopa, or levodopa doesn’t have much effect anymore
What does cutting the thalamus treat?
Tremor
What does cutting the globus pallidus internus treat?
Dyskinesia
Name two drugs that can exacerbate myasthenia gravis
Beta-blockers, ACEIs, CCBs Chloroquine Succinylcholine Magnesium Aminoglycoside and quinilone antibiotics
What is a myasthenic crisis?
Acute exacerbation when the pt is on no/little treatment
What is a cholinergic crisis?
Overtreatment leading to too much ACh in the neuromuscular junction. Causes a depolarising block.
Pt presents with the same symptoms as a myasthenic crisis
