pharmacology of parkinsons

Question 1

production sequence of dopamine

Answer 1

tyrosine -> Dopa -> dopamine

Question 2

enzyme that converts tyrosine to dopa

Answer 2

tyrosine hydroxylase

Question 3

enzyme that converts dopa to dopamine

Answer 3

L-amino acid decarboxylase

Question 4

2 pathways of dopamine metabolism

Answer 4

MAO-B

COMT

Question 5

enzyme that converts dopa into 3-o-methoxy dopa

Answer 5

catechol-o-methyl transferase

Question 6

PK of L-dopa

Answer 6

• very rapid onset

- benefits may exceed duration of the drug in plasma due to recycling

Question 7

MoA of L-dopa

Answer 7

gets taken up into dopamine neurons and converted to dopamine and then released

Question 8

too little dopamine being produced leads to

Answer 8

• wearing off

- on-off phenomenon

Question 9

too much dopamine being produced leads to

Answer 9

• dyskinesias

- hallucinations/psychosis

Question 10

when dopamine neurons are almost all degenerated how is dopamine still produced

Answer 10

• L-dopa is taken up into serotonin neurons
• aromatic amino acid decarboxylase can convert dopa to dopamine
• dopamine gets released abnormally

Question 11

where dyskinesias stem from

Answer 11

loss of dopamine neurons to reuptake dopamine so there is hyperexcitation of D1 receptors

Question 12

COMT inhibitor drugs

Answer 12

• entacapone

- entacapone + L-dopa + carbidopa

Question 13

MAO-B inhibitor drugs

Answer 13

• rasagiline

- selegiline

Question 14

COMT inhibitor MoA

Answer 14

prevent metabolic breakdown of dopa in the periphery so it can get to where it needs to be

Question 15

MAO-B inhibitor MoA

Answer 15

inhibits metabolism of dopamine in dopamine neurons to increase the amount that is available for release

Question 16

Dopamine agonists

Answer 16

• pramipexole
• ropinirole
• rotigotine

Question 17

dopamine agonist MoA

Answer 17

agonize D2 receptors in the indirect pathway

Question 18

antimuscarinic drugs

Answer 18

• trihexyphenidyl

- benztropine mesylate

Question 19

amantadine use

Answer 19

reduce dyskinesias

Question 20

amantadine MoA

Answer 20

• blockade of NMDA receptors and thus hyperactivity in subthalamic nucleus/internal Globus Pallidus pathway
• causes reduced release of glutamate in SN which ultimately increases activation of the cerebral cortex

Question 21

cofactor for L-amino acid decarboxylase

Answer 21

pyridoxal phosphate