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Anti-Parkinson Drugs - Updated
Pharm Assessment 11
33
Pharmacology
Graduate
01/08/2012

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Cards

Term
What are the 4 main clinical features of Parkinson's?
Definition
Bradykinesia
Muscular rigidity
Resting Tremor
Postural Instability and impaired gait
Term
What is the Hallmark pathophysiologic feature of parkinson's disease?
Definition
selective loss of the pigmented neurons in the substantia nigra pars compacta
Term
Describe the Direct pathway of the Basal Ganglia.
Definition
SNpc -> Dopamine -> D1 -> activates striatal neurons ---> SNpr/MGP -> Thalamus -> Cortex
Term
Describe the Indirect pathway
Definition
SNpc -> Dopamine -> D2 -> Inhibits striatal neurons -> LGP -> STN -> SNpr -> Thalamus -> Cortex
Term
Under Normal conditions what pathway is favored?
Definition
Direct Pathway
Term
In Parkinson's Disease what pathway predominates?
Definition
Indirect pathway
Term
What is the single most effective treatment for PD?
Definition
L-DOPA
Term
What are the DA replacement therapy agents?
Definition
L-DOPA
L-DOPA/carbidopa
Term
What is the mechanism of DA replacement therapy?
Definition
DA cannot cross BBB, precursor L-DOPA is used to replenish DA stores in Striatum
L-DOPA -> DA by L-AAD in periphery and Brain
Term
Why is L-DOPA co-administered with carbidopa?
Definition
can not cross BBB, prevents coversion of L-DOPA -> DA in periphery.
reduces amount of L-DOPA needed to be administered, and reduces side effects caused by peripheral DA
Term
What is carbidopa?
Definition
a L-AAD inhibitor
Can Not cross BBB
Term
What adverse effects come primarily from L-DOPA monotherapy?
Definition
GI - anorexia, nausea, vomiting
Cardiovacular - arrhythmias, ventricular extrasystoles, A. Fib, orthostatic hypertension
Term
What adverse effects occure in response to combination therapy of L-DOPA and carbidopa?
Definition
Behavioral effects
Dyskinesias
Term
What vitamin increases L-DOPA metabolism? What is needed because of this?
Definition
Vitamin B6
(pyridoxine)

Decarboxylase inhibitor also needed
Term
What agents should be avoided when taking L-DOPA, due to risk of hypertensive crisis?
Definition
MAO-A inhibitors
Term
Why should L-DOPA be given before meals?
Definition
due to competition with L-amino acids in food for transporters in GI tract
Term
How long is L-DOPA therapy effective?
Definition
3-5 years

often delayed until symptoms of PD yield functional impairment
Term
What are the Dopamine Receptor Agonists?
Definition
Bromocriptine
Pergolide
Pramipexole
Term
What is the rationale for Dopamine Agonist therapy?
Definition
to principally activate D2 receptors to reduce activation of the indirect pathway
Term
What are the advantages to DA receptor agonist therapy?
Definition
Does not need to be converted to active compound
No Toxic metabolites
No competition for GI absorption or crossing BBB
More selective = less side effects
Term
What is the preferred therapeutic stratey for early PD?
Definition
DA agonists
Term
Which DA agonist is a D2 agonist/D1 partial agonist?
Definition
Bromocriptine
Term
Which DA agonist appears more effective than Bromocriptine and is a D1/D2 agonist?
Definition
Pergolide
Term
Which DA agonist is D2 selective and also acts as a free radical scavenger?
Definition
Pramipexole
Term
Why is use of L-DOPA controversial in PD treatment?
Definition
thought that L-DOPA may exacerbate progression of PD due to generation of free radicals

(use with Pramipexole?)
Term
What drug is a selective inhibitor of COMT?
Definition
Entecapone
Term
What does inhibition of COMT do?
(Entacapone)
Definition
inhibits conversion of L-DOPA -> 3OMD, which does not cross BBB
Prolongs actions of L-DOPA, Increases bioavailability of L-DOPA
Term
What is Entacapone indicated for?
Definition

- Prolong bioavailability and action of L-DOPA by inhibiting DA metabolism by COMT

- Reduce fluctuation responses to L-DOPA

Term
What COMT inhibitor is strictly peripheral?
Definition
Entacapone
Term
What muscarinic antagonists are used in the treatment of PD?
Definition
Benztropine Diphenhydramine
Term
What are the Muscarinic Antagonists used for?
Definition
To block cholinergic activation in the striatum.
Term
When are Muscarinic Agents used in the treatment of PD?
Definition
Early PD
Prior to L-DOPA therapy
or as adjunct to L-DOPA
Term
What adverse effects do the muscarinic antagonists have? (Benztropine, Diphenhydramine)
Definition
Drowsiness mental slowness delusions hallucinations Anticholinergic Effects
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