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Ph 4 > Parkinsonism > Flashcards

Parkinsonism Flashcards

0
Q

What are the two systems?

A
  1. Pyramidal system: VOLUNTARY motor movement. It track nerve fibers that start in cerebral cortex that sends axons through the center of brain and crossing over then the spinal.
  2. Extrapyramidal System: INVOLUNTARY. There cerebellum puts the muscle into useful sequence. Dysfunction causes ataxia. The corpus striatum is involved in parkisonism, It is the highest level of organization in the extrapyramidal system, DOPAMINE and ACETYLCHOLINE are the main neurotransmitters here. DOPAMINE is affected by parkinson.
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1
Q

What is motor activity?

A

It is activity that encompasses ALL body movement, controlled movement and skeletal muscle movement.

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2
Q

What happens to dopamine neurons in parkinson?

A

Dopamine neurons cell bodies are located in the substantia nigra with their axons going into the corpus striatum. With parkinson, there is a loss of dopamine neurons from the substantia nigra leading to loss of dopamine within the corpus striatum (HYPODOPANERGIC EFFECT)

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3
Q

Is parkinson a neurogenerative disease?

A

YES because dopamine neurons die.(Affects 1% of adults over 65years, cause unknown)

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4
Q

When is parkinsonism diagnosed?

A

Once dopamine levels in corpus striatum drops to 20% (loss of 80% of dopamine levels)

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5
Q

What parkinson clinical syndrome?

A
  • Bradykinesia
  • poverty of movement
  • muscle rigidity
  • resting tremor
  • impaired postural balance
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6
Q

What are the goals of therapy?

A

-To replace dopamine lost by giving dopamine, dopamine receptor agonist and metabolizing enzyme inhibitors.
Reverse loss of dopamine neurons

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7
Q

What are structural differences of BBB and how it affected dopamine?

A

It causes blockage of some drugs in the brain. It has tight junctions in brain vessel. Drugs would need a special transported to get accross BBB. Dopamine can NOT cross BBB.

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8
Q

What is LEVODOPA?

A

A drug that replaces dopamine. It is actually a precursor for dopamine.

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9
Q

Does LEVODOPA cross BBB?

A

Yes, via the aromatic amino acid trasporter for levodopa

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10
Q

How does LEVODOPA convert to dopamine?

A

It converts by AAD (Aromatic Amino Acid Decarboxylase) enzyme. AAD is found in corpus striatum of brain.

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11
Q

Does LEVODOPA have activty by itself?

A

NO, it exerts all effect based on becoming dopamine.

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12
Q

How LEVODOPA administered?

A

ORALLY, it is rapidly absorbed, 95% metabolize to dopamine before reaching the brain, 1-5% gets into brain (which alleviate parkinson symptoms)

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13
Q

What happens to 95% LEVODOPA that does not reach the brain?

A

The 95% in the periphery increases dopamine levesl outside the brain which causes orthostatic hypotension, fainting and nausea.

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14
Q

What is the problem of LEVODOPA?

A

Rapid peripheral metabolism by AAD

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15
Q

What drug is the solution to the rapid metabolism of LEVODOPA outside the brain?

A

CARBIDOPA- given WITH Levodopa.

16
Q

How does CARBIDOPA work?

A

It works by INHIBITING AAD enzyme.

17
Q

What is the drug combination of LEVODOPA + CARBIDOPA called?

A

SINEMET

18
Q

Does CARBIDOPA cross BBB?

A

NO, it does NOT cross BBB. It only works outside the brain (inhibiting peripheral AAD only). Which is good, you not want to inhibit AAD in brain.

19
Q

What are few benefits of using CARBIDOPA?

A
  • It allows the use of lower doses of LEVODOPA than with LEVODOPA by itself.
  • SINEMET is effective because it decrease LEVODOPA side effects. It is standard of current treatment of parkison.
20
Q

What is another problem with LEVODOPA?

A

It is metabolize by Catechol-O-Methyl transferase (COMT), which is found in the liver and GI tract.

21
Q

What is the solution to COMT metabolism?

A

Drugs TOLCAPONE and ENTACAPONE: which inhibit COMT.

22
Q

Can ENTACAPONE cross BBB?

A

No, it can NOT cross BBB (just periphery, outside brain)

23
Q

Can TOLCAPONE cross BBB/

A

Yes, it CAN cross BBB. It is inside and outside the brain.

24
Q

What is effect of SINEMET and a COMT inhibitor?

A

It increases effect of LEVODOPA. These 3 drugs reduced the “WEARING OFF” Phenomenon.

25
Q

What are limitations of LEVODOPA therapy?

A

1.”Wearing Off” Phenomenon: initially when given, leveodopa parkison symptoms are treated well, after sometime and before the next dose parkinson symptoms reappear. This is due to levodopa short 1/2 life of about 2 hrs.

This can be fixed with 1. an increase dose of LEVODOPA, 2. decrease time in interval between doses 3. Add COMT inhibitor 4. a sustain release formula (such as SINEMENT CR)

26
Q

Can LEVODOPA adversely accelerate the disease?

A

Yes, the metabolism of dopamine produces free peroxide radicals that contribute to death of the dopamine neurons in the corpus striatum by oxidated stress (this is an unwanted reaction).

27
Q

Should you start patients with LEVODOPA therapy?

A

No, start with another neuroprotective drug therapy and save levodopa therapy for later (after nothing else works).

*Also patients become less responsive to LEVODOPA due to death of dopamine neurons causing lost of AAS enzyme that is needed for levodopa in dopamine conversion.

28
Q

What drugs are Dopamine Receptor AGONIST?

A
  • PramipexOLE

- RopinirOLE

29
Q

How are these Dopamine Receptor agonist drugs better than levodopa?

A
  1. They bind to the same receptors as dopamine
  2. they cross the BBB
  3. they avoid free radicals caused by dopamine metabolism
  4. Suggested in early stages of parkinson (to protect neurons)
  5. They don’t depend on dopamine neurons in corpus striatum
  6. Has great affinity for D3 receptors thant D2 and D1 . These increase motor function.
  7. Longer half life than Levodopa which reduces “Wearing off” in comparison to levodopa
  8. Possess desirable neuroprotective properties.
30
Q

What does MonoAmine Oxidase Type B do?

A

These metabolize dopamine and are found in nondopaminegic and presynaptic dopamine neurons

31
Q

What drug is MAO type B INHIBITOR?

A

SELEGILINE- it INHIBITS MAO-B, which reduces symptoms of parkinson.

32
Q

What are the benefits SELEGILINE?

A
  1. Keeps dopamine levels high
  2. Enhances therapeutic effect of LEVODOPA(can be given together)
  3. Neuroprotective ability (prevents oxidative stress)
  4. Used in new diagnosed parkison patients
  5. Slow progress of parkinson
  6. When used alone, it delays the start of levodopa therapy because it keep dopamine levels high by itself
  7. Dopamine release increase due to selegline being metabolize as amphetamine and methamphetamine which cause increase release of dopamine vessicles in axon terminals.
33
Q

What are NON-PHARMacologic treatment?

A

After 10 years on drug or drugs, they develop a reduced effect and are less effective.

  1. A surgical approach is Neuroablative techniques and Deep brain stimulating electrodes implantation.
    2,Experimental approach is gene transfer techniques, using cannula to inject into them (Glial Derived Neurotropic Factor-GDNF)

Ph 4 (7 decks)

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