Parkinson disease (paralysis agitans) (drugs that increase dopamine levels) Flashcards Preview

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Flashcards in Parkinson disease (paralysis agitans) (drugs that increase dopamine levels) Deck (23)
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1

Drugs for PD - 3 groups of drugs

Drugs that increase dopamine levels.
Dopamine receptor agonists.
Centrally acting ACh receptor antagonists.

2

Drugs that increase dopamine levels in PD - 7 drugs

Levodopa
Carbidopa
Amantadine
Selegiline
Rasagline
Tolcapone
Entacapone

3

When is levodopa effective in PD?

As long as there are dopaminergic neurons are still alive. Counteract all signs of parkinsonism.
Fluctuation in effectiveness: wearing-off effect and on-off effect.

4

Levodopa - indications

Idiopathic PD.
Postencephalitic parkinsonism.
Parksonian symptoms (CO poisoning, manganese intoxication, cerebral atherosclerosis).

5

Pts on .... for PD should not take which vitamin and why?

Levodopa.
Vit B6: enhance peripheral decarboxylation of levodopa.

6

Levodopa - adverse effects

Nausea, vomiting (80%).
Orthostatic hypotension (25%).
Psychotic symptoms (agitation, delirium, distorted thinking, hallucinations).
Dyskinesia, nightmares, vivid dreams, sedation. Euphoria. Arrhythmias

7

Levodopa - interactions

Antacids increase bioavailability.
Anticholinergic drugs reduce peak serum levels.
Antipsychotics decrease effects of levodopa. Nonselective MAOIs cause hypertensive crisis.
Dietary amino acids decrease bioavailability.
Vit B6: enhance peripheral decarboxylation of levodopa.

8

Which antipsychotic can be used in pts with PD and why is this a good choice?

Clozapine less likely to block dopamine receptors and decrease effects of levodopa

9

Levodopa - diet

Protein-restricted diet because dietary amino acids decrease bioavailability and levodopa uptake to the brain.

10

Carbidopa - MOA

Inhibits dopamine synthesis in peripheral tissues by blocking LAAD.
Increase the amount of levodopa that enters the brain.

11

Carbidopa - indications

Reduction in levodopa dosage (by 75 %).
Reduces GI and cardiovascular effects of levodopa.

12

Amantadine - Classification and MOA

Antiviral drug.
Increases dopamine release from nigrostriatal neurons, and inhibits reuptake of dopamine.

13

Amantadine - indications

Influenza.
Adjunct to levodopa in early or mild cases

14

Amantadine - adverse effects

Dry mouth.
Hypotension.
Livedo reticularis
Nausea
Restlessness, sedation, vivid dreams.
CNS adverse effects are more likely in elderly.

15

Amantadine - interactions

Benzotropine and trihexyphenidyl potentiate CNS effects

16

Selegiline, rasagline - MOA

Inhibits dopamine breakdown by inhibiting MAO-B, preventing oxidation of dopamine.
Decreases formation of hydrogen peroxide.

17

Selegiline - interactions

Meperidine/fluroxetine/other SSRI: severe reactions.
High doses: Interaction with foods containing thyramine.

18

Selegiline - indications

Single treatment for early/mild PD.
Adjunct to levodopa-carbidopa for advanced disease

19

Rasagline - indications

Monotherapy or adjunct for PD

20

Rasagline, selegiline - adverse effects

Confusion
Dyskinesias
Hallucinations
Hypotension
Insomnia
Nausea

21

Tolcapone and entacapone- MOA

Inhibits COMT and prevents conversion of levodopa to 3OMD.
Stabilizes dopamine levels in striatum. Increase efficacy of levodopa, reducing the dosage requirement.

22

Tolcapone - adverse effects

Diarrhea and nausea.
Rare but fatal hepatitis

23

Difference between entacapone and tolcapone

entacapone is more restricted to peripheral tissues, and causes no hepatic toxicity