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Pharmacology I > 1 - CNS Part I > Flashcards

1 - CNS Part I Flashcards

1
Q

How many neurotransmitters are used in the PNS?

How many are used in the CNS?

A

PNS: 3

CNS: 21

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2
Q

The motor symptoms of parkinson disease result from damage to the:

A

Extrapyramidal system: a complex neuronal network that helps regulate movement

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3
Q

What are dyskinesias?

A

disorders of movement

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4
Q

In PD, neurotransmission is disrupted primarily in:

Why?

A

the striatum

Degeneration of neurons in the substantia nigra that supplies dopamine to the striatum

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5
Q

Two neurotransmitters balance striatal neurotransmission:

A

Dopamine inhibits GABA release

Acetylcholine excites GABA release

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6
Q

What happens when dopamine is absent in the striatum?

A

Overactivity of GABAergic neurons

contributes to the motor symptoms

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7
Q

To treat PD, two types of drugs are used:

A
  1. Dopaminergics (indirectly activate dopamine receptors)
  2. Anticholinergics (block receptors for Ach)
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8
Q

Long term treatment with levodopa or a dopamine agonist is associated with two types of motor fluctuations:

A
  1. “Off” times where symptom relief is lost
  2. Drug-induced dyskinesias
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9
Q

What is the most effective drug for PD?

A

Levodopa

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10
Q

How long is Levodopa effective?

A

Works well for the first two years, but by the end of year 5 its function may deteriorate

THIS IS DUE TO DISEASE PROGRESSION, NOT TOLERANCE

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11
Q

What is Levodopa’s MOA?

A

Converted to dopamine in the remaining dopaminergic nerve terminals of the striatum

via the enzyme decarboxylase

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12
Q

Why isn’t PD just treated with dopamine?

A

Dopamine can’t cross the BBB

Dopamine has an extremely short half life

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13
Q

When and with what foods should levodopa be taken?

A

on an empty stomach

amino acids compete with Levodopa for absorption, so high protein foods reduce therapeutic effects

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14
Q

What should you warn patients about before starting Levodopa?

A

It will takes weeks to months to start working

Possibility of “off” times

N/V is improved by taking the drug with low fat, low protein foods (fruits and veggies)

Watch out for drug-induced dyskinesias

Watch out for cardiac s/s

May have orthostatic hypotension initially

May have vivid dreams or psychoses. If so, need to see you immediately

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15
Q

What percentage of patients taking levodopa develop drug-induced dyskinesias?

A

80% within the first year

Develop just before or soon after optimal dosage has been achieved

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16
Q

What are some options for dealing with drug-induced dyskinesias 2/2 levodopa?

A
  1. Adjust the dose of levodopa (reduce)
  2. Amantadine
  3. Surgery and/or electrical stimulation
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17
Q

A patient taking levodopa tells you his urine is dark. What should you say?

A

This is a normal effect of the drug and is harmless

18
Q

Why is a thorough skin assessment wise for a patient on levodopa?

A

It can activate malignant melanoma (Maybe, no one is sure)

19
Q

Which drugs increase the beneficial effects of levodopa?

A

Carbidopa (inhibits decarboxylation)

Entacapone (inhibits COMT breakdown)

Apomorphine (stimulates dopamine receptors directly)

Amantadine (promotes release of dopamine)

Anticholinergics (help restore balance between dopamine and Ach by blocking Ach)

20
Q

Which drugs decrease the beneficial effects of levodopa?

A

First generation antipsychotics

(chlorpromaxine, haldol)

They block receptors for dopamine in the striatum

21
Q

Can you use seroquel in a patient with PD?

A

Yes! Seroquel and clozapine do not block dopamine receptors in the striatum

21
Q

Can you use seroquel in a patient with PD?

A

Yes! Seroquel and clozapine do not block dopamine receptors in the striatum

22
Q

Why is it essential that patients taking levodopa not take MAOIs?

A

Levodopa can cause a hypertensive crisis:

  1. It elevates neuronal stores of dopamine and NE by promoting synthesis of both
  2. MAO inactivates dopamine and NE ordinarily, but in patients on MAOIs they build up unchecked
  3. Release of both agents in the blood stream causes massive hypertension
23
Q

What is Sinemet?

A

Levodopa/Carbidopa

24
Q

What does Carbidopa do?

A

Inhibits decarboxylation of levodopa in the intestines and peripheral tissues

25
Q

What is the first choice drug for a patient with very mild PD symptoms?

A

A dopamine agonist

26
Q

List the dopaminergic drugs and their actions:

A
  1. Levodopa (increases dopamine synthesis
  2. Carbidopa (blocks levodopa destruction)
  3. Pramipexole (binds to dopamine receptors directly)
  4. Entacapone (Inhibits COMT)
  5. Selegiline (Inhibits MAO-B)
  6. Amantadine (Promotes dopamine release)
27
Q

What is Requip?

A

Nonergot dopamine agonist

28
Q

What is unique about apomorphine?

A

dopamine agonist used for acute hypomobility during off episodes

Cannot be given by mouth and is not used for routine treatment

It’s a derivative of morphine but has none of the opioid effects

29
Q

What should patients be warned about before beginning a dopamine agonist?

A
  1. N/V canbe reduced by taking with food. Apomorphine may require tigan.
  2. Orthostatic hypotension
  3. Movement disorders may occur
  4. can cause hallucinations
  5. can cause sleep attacks
  6. may harm a developing fetus
30
Q

What is the benefit of adding an MAO-B inhibitor with levodopa?

A

Reduces the wearing off effect of levodopa

MAO-B is the enzyme that inactivates dopamine in the striatum

31
Q

A patient taking Selegiline is feeling shaky in the OR. Which drug should NOT be given?

A

Demerol

32
Q

What is amantadine?

A

It’s actually an antiviral drug that was discovered to be effective against PD

Helpful in managing dyskinesias caused by levodopa

33
Q

In PD, anticholinergics can improve _____ and _____, but not ______

A

tremor and rigidity

NOT bradykinesia

34
Q

What are some of the autonomic symptoms associated with PD?

A

constipation, urinary incontinence, drooling, orthostatic hypotension, cold intolerance, ED

Sleep disturbances

Depression

Dementia

Psychosis (usually caused by the drugs taken)

35
Q

There are two drug types that are used to reduce symptoms of AD:

A

Cholinesterase Inhibitors (Aricept)

NMDA receptor Antagonists

36
Q

How effective are cholinesterase inhibitors in treating AD symptoms?

A

Only benefits 1 in 12 patients, and improvements are modest and short lived

37
Q

What are some adverse effects of cholinesterase inhibitors?

A

they elevate Ach in the periphery:

N/V/D

Dizziness and headache

Bronchoconstriction

Symptomatic Bradycardia

38
Q

Which cholinesterase inhibitors used to treat AD are reversible? which are irreversible?

A

Reversible: Donepezil (Aricept), Galantamine (Razadyne)

Irreversible: Rivastigmine

39
Q

What NMDA receptor antagonist is used to treat AD?

A

Memantine

40
Q

What is the major excitatory transmitter in the CNS?

A

Glutamate

41
Q

How does Memantine impact AD symptoms?

A

Modulates the effects of glutamate at NMDA receptors

It blocks calcium influx when extracellular glutamate is low, but permits calcium influx when extracellular glutamate is high

It’s basically a plug in the pathologic absence of a magnesium plug

Pharmacology I (29 decks)

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