Anti- Parkinson Drugs Flashcards
What is the effect of a lesion in the extra pyramidal motor path?
Tremor at rest; Rigidity
What is the pathogenesis of Parkinson’s?
Loss of dopamine-secreting cells in the pars compact of the substantia nigra.
What are some iatrogenic causes of Parkinson’s?
Drugs that reduce dopamine activity.
Why do haloperidol and phenothiazines cause PD?
They block DA receptors.
Why do reserpine and tetrabenzine cause PD?
They deplete brain monoamines from storage sites.
Why does manganese poisoning cause PD?
It accumulates in the substantial nigra and interferes with enzyme systems. Oxidizes DA.
True or false: In PD the DA system is severely compromised and the cholinergic system operates unopposed?
True. Treatment thus involves restoring balance.
What does L-DOPA do?
It is a dopaminergic drug (precursor of DA) that increases DA activity.
Can L-DOPA cross the BBB?
Yes.
What is the response rate to L-DOPA and is it safe to use?
Response rate is high; Generally safe.
What are the adverse effects of L-DOPA?
Nausea, confusion
What does Carbidopa do?
Inhibits decarboxylase activity in the periphery. This prevents conversion of L-DOPA to DA.
Can Carbidopa cross the BB?
No.
How does Entacapone work?
It is a COMT inhibitor. Adjunct with L-DOPA. Entacapone prolongs L-DOPA action. Acts peripherally to reduce L-DOPA metabolism.
How does Tolcapone work?
COMT inhibitor. Acts peripherally and centrally.
What are the adverse effects of Tolcapone?
Can be hepatotoxic.
How does Amantadine work?
Enhances endogenous DA. It acts on release/synthesis/reuptake.
True or false: Amantadine is also an anti-viral agent for the A2 influenza.
True.
How does Bromocriptine work?
Agonist to D2 and partial antagonist to D1 receptors.
True or false: Bromocriptine has a longer duration of action that L-DOPA.
True.
When is Bromocriptine used?
Used as an adjunct in late treatment. Combats on/off effect.
How does Pergolide work?
Agonist to D1 and D2 receptors. More potent than Bromocriptine.
True or false: Pergolide has a longer duration of action that L-DOPA and less on/off effect.
True.
How does Pramipexole work?
It is a DA agonist (D3). Used as adjunct with L-DOPA.
When is Pramipexole used?
When the PD is mild.
True or false: Pramipexole is possibly neuroprotective.
True. It scavenges H2O2.
How does Ropinrole work?
It is a DA agonist (D2). Smoothes fluctuations in response to L-DOPA treatment.
When is Ropinirole used?
When the PD is mild.
What are the toxic side effects from L-DOPA mainly due to?
The conversion of L-DOPA to DA in the periphery.
What are the toxic side effects of L-DOPA?
Nausea/vomiting, orthostatic hypotension, dyskinesia, mental effects.
How does vitamin B6 reduce L-DOPA activity?
It increases dopa decarboxylase activity.
What is the effect of MAO inhibitors?
They increase DA activity. MAOb breaks down DA. MAOa breaks down NE and 5HT in the CNS.
Why can a high protein meal affect PD treatment?
It can interfere with the absorption of L-DOPA from the gut.
True or false: Benserazide inhibits decarboxylase activity in the periphery and has a longer duration of action that carbidopa.
True.
How does Selegiline work?
Increases DA activity by inhibiting MAO-B activity.
Benzotropine, Biperiden, Orphenadrine, Procyclidine, and Trihexyphenidyl are what kind of drugs?
Anti-cholinergic drugs. They decrease Ach activity.
What is the mechanism of action of the anti-cholinergic drugs?
They are all Ach (muscarinic) blockers.
What is MPTP?
A drug that causes PERMANENT PD. It is a neurotoxin to substantia nigra cells.
What does a Thalamotomy procedure do?
Reduces tremor.
What does a Pallidotomy do?
Lessens motor fluctuations permanently.
What dose Pallidal stimulator do?
Lessens fluctuations. Can be regulated.
