Anti-parkinson medications Flashcards
What is the neurologic target of parkinson’s medications ?
Nigrostriatal pathway.
What is the enzyme responsible for converting Levadopa to dopamine ?
DOPA decarboxilase
Why is levodopa is contraindicated in patients with psychosis ?
It can augment positive symptoms of psychosis such as hallucinations and delusions.
What is the main side effect of chronic levodopa use ?
Dyskinesia due to nigrostriatal neurons progressive lose of the capacity to store and recycle dopamine.
What are the peripheral side effects of dopamine agonists due to the presence of the enzyme DOPA decarboxilase ?
Nausea, vomiting, anorexia, and orthostatic hypotension.
How does dopamine agonists cause tachycardia and arrhythmias ?
These are due to the enzymatic peripheral conversion of dopamine into other catecholamines such as epinephrine.
How can we prevent the cardiac side effects of Levodopa ?
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.
What are the dopamine analogues or agonists used in PD ?
Bromocriptine, Pramipixole, Ropinirole. They have short half life and are used alone or with levodopa.
What are the side effects of dopamine agonist Bromocriptine ?
Nausea, vomiting, somnolance, and pulmonary fibrosis. Therefore, Pramipixole and Ropinirole are preferred over bromocriptine as they only cause somnolence.
what are the Catechol-o- Methyletransferase (COMT) inhibitors that prevent the breakdown of dopamine in the CNS ?
Entacapone and Tolcapone.
The enzyme COMT converts dopamine to _________
3- Methoxythyramine.
The enzyme COMT converts levodopa to _________
3-o-methyldopa.
What is the only COMT inhibitor that can prevent the degradation of endogenous dopamine ?
Tolcapone
What are the side effects of COMT inhibitors ?
Nausea, orthostatic hypotension, confusion, and hallucination.
Why is Tolcapone the last option for treating PD?
because of liver toxicity and if used hepatic enzymes should be checked regularly to monitor liver function.
What is the MOA of the enzyme MAO-B on dopamine ?
It breaks down dopamine to 3,4-Dihydroxyphenylacetic acid (DOPAC).
What are the MAO-B inhibitors used in PD ?
Selegiline and Rasagiline and are used to treat mild symptoms in early stage PD.
What is the effect difference of various MAO-B inhibitors & Levodopa co-administration ?
- Rasagaline and levodopa reduces motor symptoms.
- Selegilne and levodopa increases motor symptoms.
Why does selegiline cause symptoms such as insomina, excitement and anxiety ?
It gets converted to Amphetamine
What is the antiviral used to treat PD ?
Amantadine which is thought to increase dopamine release and reduce dopamine re-uptake. It is best used to treat mild PD.
Osmosis link to PD drugs
https://www.osmosis.org/learn/Anti-parkinson_medications?from=/pa/foundational-sciences/pharmacology-and-pharmacotherapeutics/neurologic-system/neurodegenerative-disease-medications/parkinson-disease
