Anti-parkinson medications Flashcards

1
Q

What is the neurologic target of parkinson’s medications ?

A

Nigrostriatal pathway.

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2
Q

What is the enzyme responsible for converting Levadopa to dopamine ?

A

DOPA decarboxilase

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3
Q

Why is levodopa is contraindicated in patients with psychosis ?

A

It can augment positive symptoms of psychosis such as hallucinations and delusions.

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4
Q

What is the main side effect of chronic levodopa use ?

A

Dyskinesia due to nigrostriatal neurons progressive lose of the capacity to store and recycle dopamine.

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5
Q

What are the peripheral side effects of dopamine agonists due to the presence of the enzyme DOPA decarboxilase ?

A

Nausea, vomiting, anorexia, and orthostatic hypotension.

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6
Q

How does dopamine agonists cause tachycardia and arrhythmias ?

A

These are due to the enzymatic peripheral conversion of dopamine into other catecholamines such as epinephrine.

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7
Q

How can we prevent the cardiac side effects of Levodopa ?

A

These can be prevented by inhibiting the enzymatic conversion of levodopa to catecholamines by combing levodopa with carbidopa which is a dopa decaraboxilase inhibitor which prevents the conversion of Levodopa to dopamine outside the CNS.

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8
Q

What are the dopamine analogues or agonists used in PD ?

A

Bromocriptine, Pramipixole, Ropinirole. They have short half life and are used alone or with levodopa.

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9
Q

What are the side effects of dopamine agonist Bromocriptine ?

A

Nausea, vomiting, somnolance, and pulmonary fibrosis. Therefore, Pramipixole and Ropinirole are preferred over bromocriptine as they only cause somnolence.

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10
Q

what are the Catechol-o- Methyletransferase (COMT) inhibitors that prevent the breakdown of dopamine in the CNS ?

A

Entacapone and Tolcapone.

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11
Q

The enzyme COMT converts dopamine to _________

A

3- Methoxythyramine.

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12
Q

The enzyme COMT converts levodopa to _________

A

3-o-methyldopa.

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13
Q

What is the only COMT inhibitor that can prevent the degradation of endogenous dopamine ?

A

Tolcapone

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14
Q

What are the side effects of COMT inhibitors ?

A

Nausea, orthostatic hypotension, confusion, and hallucination.

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15
Q

Why is Tolcapone the last option for treating PD?

A

because of liver toxicity and if used hepatic enzymes should be checked regularly to monitor liver function.

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16
Q

What is the MOA of the enzyme MAO-B on dopamine ?

A

It breaks down dopamine to 3,4-Dihydroxyphenylacetic acid (DOPAC).

17
Q

What are the MAO-B inhibitors used in PD ?

A

Selegiline and Rasagiline and are used to treat mild symptoms in early stage PD.

18
Q

What is the effect difference of various MAO-B inhibitors & Levodopa co-administration ?

A
  • Rasagaline and levodopa reduces motor symptoms.
  • Selegilne and levodopa increases motor symptoms.
19
Q

Why does selegiline cause symptoms such as insomina, excitement and anxiety ?

A

It gets converted to Amphetamine

20
Q

What is the antiviral used to treat PD ?

A

Amantadine which is thought to increase dopamine release and reduce dopamine re-uptake. It is best used to treat mild PD.

21
Q

Osmosis link to PD drugs

A

https://www.osmosis.org/learn/Anti-parkinson_medications?from=/pa/foundational-sciences/pharmacology-and-pharmacotherapeutics/neurologic-system/neurodegenerative-disease-medications/parkinson-disease