42 Neuro Drugs (Parkinsons) Flashcards by Yvonne Little

How do Dopaminergic Agents treat Parkinsons?
How do Anticholinergic Agents treat it?

Is there a cure for Parkinsons?

Dopaminergic Tx:
Restore or enhance dopamine activity

Anticholinergic:
Prevent activation of cholinergic receptors

No, and no treatment to slow progression

Just manage symptoms

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What can be used to replace dopamine in the CNS and why?

Replace dopamine with L-Dopa. L-Dopa can X BBB and dopamine can not. Once L-dopa crosses over, it will be converted to dopamine.

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What symptoms does L-Dopa reduce?

Rigidity
Tremors
Bradykinesia
Gait (impaired walking)
Hypomimia (reduced facial expression)
Microphagia (small cramped writing)

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Why do you have to give large amounts of L-dopa? How can this be prevented? What SEs are large doses assoc’d with?

Large amounts needed bc L-dopa gets converted in the PERIPHERY by:
PERIPHERAL DOPA DECARBOXYLASE (DDC)

This can be prevented if L-Dopa administered with CARBIDOPA which is a peripheral DDC Inhibitor

L-Dopa ALWAYS given with Carbidopa (or a DDC Inhibitor)

Benserazide is also a DDC Inhibitor

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Does Carbidopa X BBB?
What is its goal?
What does it reduce?

No it doesn’t

Goal: Prevent breakdown of L-Dopa BEFORE it X BBB

Reduces: L-dopa dose by 70% therefore also reducing N/V and cardiac arrythmias

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What is Benserazide?

It is a Peripheral DDC Inhibitor

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In addition to DDCs, what else breaks down L-Dopa? What is it broken down to?

COMT (catechol-O-methyl transferase)

Broken down to 3-O-Methyldopa (3-OMD)

When DDCs are inhibited, COMT takes over L-Dopa breakdown

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In addition to Carbidopa, what else should be added to L-Dopa to prevent its breakdown?

COMT Inhibitors

Improves the delivery and action of L-Dopa`

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What are some COMT inhibitors prescribed for Parkinsons and what stages of Parkinsons?

ENTACAPONE
Tolcapone
Stalevo (L-Dopa + Carbidopa + Encatapone in one pill)

Moderate to severe Parkinsons

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What are the SEs of COMT Inhibitors?

DIARRHEA

N/V, 
sleep disturbances, 
dizziness, 
urine discoloration
HypoTN
Hallucinations
May worsen L-dopa SEs

Tolcapone (NOT ENTACAPONE) has caused severe liver disease, so monitor renal function while on this

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What is the plasma 1/2 life of L-Dopa?
What is it when carbidopa and L-dopa given together

How is L-Dopa formulated?

1/2 Life ~ 50 mins
L-Dopa and carbidopa together is 1.5 hours

Formulated in a single pill with DDC Inhibitor w or w/o a COMT inhibitor

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What are the initial SEs of L-Dopa? Long Term?

Initial:
Peripheral effects, i.e. GI upset, Dizziness, fainting, Restlessness, drowsiness or sudden sleep
- can reduce this by reducing carbidopa or other DDCs

Long Term:
After like 5 or 10 years get MOTOR COMPLICATIONS and DECREASED EFFECTIVENESS

Behavioral disturbances, mood swings, anxiety, psychosis

Cardiac effects, i.e. arrythmias

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What are the MOTOR complications of L-Dopa over time?

Delayed Onset 
Dose Failures
End of Dose (Wearing Off)
On/Off Phenomena
Dyskinesias

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What are the DELAYED ONSET AND DOSE FAILURES OF MOTOR complications of L-Dopa over time?

Delayed:

Medication takes longer to start working. May be worsened by high protein diet
bc AAs compete with L-Dopa for transporters in the gut wall ( so no absorption) and in the BBB (so brain levels are reduced)

Dose Failures:
Immobility bc the dose didn’t work

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What are the End of Dose MOTOR complications of L-Dopa over time?

How can it be fixed?

Daily fluctuations in control of mvmt. Drug feels like its wearing off. This worsens over time. Like have total control, then less control

Can fix by adjusting to an extended duration dose and supplement with more frequent dosing, and add additional drugs like COMT Inhibitors

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What are the On/Off MOTOR complications of L-Dopa over time?

Periods of normal mvmt when they are on, then times when it feels like the drug not working at all, then they cannot move, i.e. walk. This is the off.

Changes in mobility may be sudden and unpredictable.

UNRELATED TO DOSE TIMING…so its not like you need to decrease the time btwn doses. won’t help

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What are the Dyskinesias MOTOR complications of L-Dopa over time?

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Periods of drug induced dyskinesias and dystonia that usu develops after years of taking L-Dopa
-May be a striatal compensatory mechanism to drug and disease progression

Most often a peak dose effect in ON period.

How can the drug induced dyskinesias be fixed? How can it be avoided in younger PD patients?

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Reduce the L-Dopa dose to lessen dyskinesias and dystonias

but the symptoms reappear
Can switch to or add other drugs such as DA agonists or MAO-B Inhibitors, glutamate antagonists, or antipsychotics

Can avoid this by starting younger patients on other DA increasing drugs (they stimulate dopamine production and release)

Switch to L-Dopa when these stop working
This delays the development of Dyskinesias

How do dopamine agonists work?
What are they good at controlling?
How is it better than L-Dopa?
How is it worse?

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Mimic dopamine at DA receptors

Can control most motor symptoms of early Parks
-ie slowness and stiffness

Better: Lower response fluctuations and dyskinesias
Worse: Not as effective, more SEs

What are the DA agonists at D2 Receptors?

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PR for the BRA

Pramipexole
Ropinirole

Bromocriptine
Rotigotine
Apomorphine

What is Ropinirole?

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D2 agonist with some effect at D3/D4

What is Pramipexole?

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D2-4 agonist

What is Rotigotine?

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D2-3 agonist in skin patch. Transdermal sys

What is Bromocriptine? Who is it more toxic than?

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D2 agonist
Ergot Derivative
More toxic than Pramiprexole, ropinirole, rotigotine (all these are the other D2 agonists)

What is Apomorphine? This has a special use (hint its a subcu injectable)? Whats the SE here?

Non selective for either D1 or D2 agonist Short acting rescue treatment of L-Dopa in the OFF episodes High incidence of N/V

What are the peripheral and motor SEs of DA agonists?

``` Heart and CV: Postural HypoTN Periph Edema Cardiac Arrythmias Increased risk of heart failure with PRAMIPEXOLE ``` GI: N/V (so take these with meals) Dyskinesias may occur. if they do, reduce the dose

What drug has a FDA 2012 warning that said there was an increased risk of heart failure?

Pramipexole

What are the CNS SEs of DA agonists?

``` CNS: CNS disturbances like sudden excess sleepiness, so be cautious when driving Confusion Compulsive Behaviors -gambling, overating, hypersexed -D3, symptoms stop if med stopped ``` Psychiatric: Delusions, hallucinations -esp with high doses, but stop if drug is stopped

What are the uses of DA agonists?

First line therapy for newly diagnosed and younger patients - wanna delay the use for L-Dopa as long as possible Can give alone or with L-Dopa L-Dopa rescue during Off phenomena

What other condition is DA agonist used in? Which ones specifically?

Restless Legs Syndrome Take before bedtime, and helps improve sleep Pramipexole, Ropinirole, & Rotigotine

How can MAO Inhibitors be used to treat Parks?

DA is metabolized by MAO-B, so if you inhibit it, you can keep DA around

Name some MAO-B inhibitors for Parks? | Who are they commonly used for?

Selegiline Rasagiline Used for mild or early Parks May delay L-Dopa for up to a year Can be given with L-Dopa to make it more efficacious

What is Selegiline? What is it a derivative of? What about its metabolism What can chronic exposure of metabolites lead to?

First gen MAO-B Inhibitor Amphetamine. Undergoes FIRST PASS metab to L-meth & L-amphetamine Chronic exposure to metabolites induce cardiac and pyschiatric effects

What is Rasagiline?

2nd generation MAO-B Inhibitor More potent than selegiline, NO AMPHETAMINE METABOLITES

What are SEs of MAO-B Inhibitors?

Well tolerated but... N/V, orthostatic HypoTN, insomnia, confusion, HA. hallucinations DO NOT USE IN COMBO WITH: ANTIDEPRESSANTS MEPERIDINE CIPRO (antibiotic)

``` What is Amantadine? What can it directly fix in Parks? How is it helpful with L-Dopa medication? When can it be used? What other drugs can it be used with? SEs? ```

Promotes Dopamine release. also NMDA glutamate receptor antagonist Directly fixes the tremor, rigidity and bradykinesia (modestly) L-Dopa: treats the dyskinesias that this produces Used alone in the EARLY stages of Parks -but wears off after a few months in half of ppl can be used with ANTICHOLINERGIC drugs or L-Dopa SEs: Cognitive, Insomnia, Mottled skin, edema, agitation, hallucinations

How are Anticholinergic drugs used to treat Parks?

Restores balance btwn Ach and DA in striatum Musc Receptor Antagonist Helpful for tremor and rigidity (muscle stiffness)

What are the Anticholinergics used in Parks? Benefits? What is not effective for? SEs?

The Musc Receptor Antagonists - Benzotropine - Trihexyphenidyl Modest benefit bc only half are helped for the tremor and rigidity for a short time Not effective for bradykinesia SEs - Anticholinergic syndrome so everything dry... - dry mouth, constipation, urinary retention, blurry vision (mydriasis) memory loss, hallucinations, confusion

What are Benztropine & Trihexyphenidyl?

These are anti-muscarinics used in Parks

What is the second most common form of Parks? What legal drugs cause it? Can it be reversed?

Drug Induced Metoclopramide Amoxapine Can't tell this from reg Parks, and has at least two of the following: - tremor, rigidity, bradykinesia Reversible if stop meds...but takes months to years or can reduce dose, switch to atypical antipsychotic, use AMANTADINE and maybe a anti-muscarinic

What causes chemical toxin induced Parks? What is it metabolized by? How does it cause Parks? How can you protect against it?

MPTP... Meperidine contaminated with MPTP Metabolized by MAO-B into MPP+ - toxic and accumulates and causes death of DA neurons Protect against this with MAO-B Inhibitors so that the metabolite isn't made.

42 Neuro Drugs (Parkinsons) Flashcards

(41 cards)