Parkinsonism

Question 1

Describe effect of carbidopa co-adminstered with L-dopa

Answer 1

Decreases dose by 75%as it prevents peripheral dopa decarboxylation, & decreases preipheral side effects. Without it 97-99% of L-dopa would be decarboxylated peripherally.

Question 2

Mention adverse effects of L-dopa

Answer 2

Peripheral: GIT disturbance, postural hypotension, arrhythmias
Central: dyskinesia (choreoathetosis), confusion, hallucinations
Fluctutations: on-off effet (swings from bradykinsia to mobility) & end of dose akinesia

Question 3

Mention drug of choice in L-dopa nausea & why?

Answer 3

Domperidone
Does not cross BBB, blocks D2 in CTZ but not in BG thus does not interfere with L-dopa

Question 4

Describe mechanism of action & adverse effects of ropinirole

Answer 4

Direct D2 agonist less fluctuation due to rapid absorption & long t1/2
Similar to L-dopa:hallucination, dyskinesia, nausea, postural hypotension, impulse control disorder, day time sleepiness.

Question 5

Mention a side effect specific to bromocriptine

Answer 5

Vasospasm & cardiac & retroperitoneal fibrosis

Question 6

Describe mechanism of action & adverse effects of amantadine

Answer 6

Inc DA release (mild), NMDA receptor blocker, used in combination with other drugs as tolerance develops rapidly
Livido reticularis, ankle edema, insomia, hallucination

Question 7

Describe mechanism of action & adverse effects of selegiline

Answer 7

Insomnia, hallucination, very low risk of cheese reaction

Question 8

Describe mechanism of action & adverse effects of entacapone

Answer 8

COMT inhibitor, dec L-dopa peripheral metabolism, inc bioavailability & prolongs its action, dec flutuations
AE, related to L-dopa/carbidopa (hallucination, dyskinesia, nausea, postural hypotension), orange urine

Question 9

Indications of apomorphine

Answer 9

Rescue therapy in patients having sudden akinetic episode
Given intermittently subcutaneously to decrease off-time in advanced parkinson’s

Question 10

Mention anticholinergics in used parkinson’s

Answer 10

Benztropine
Trihexphenidyl

Question 11

Mention uses of anticholinergics

Answer 11

1. Drug induced parkinson since dopaminergic agents cannot be given in antipsychotic induced parkinsonism as it may worsen psychosis
2. Adjuvants to dopaminergic drugs in cases presenting with tremors & to control sialorrhea especially in young patient

Question 12

GR: Anticholinergics should be used cautiously invelderly

Answer 12

As they increase memory loss& hallucination, urine retention in enlarged prostate

Question 13

…..is most effective against motor complications

Answer 13

L-dopa

Question 14

To avoid L-dopa related motor complications other agents are used first in….&…

Answer 14

Mild cases
When tremor is only symptom

Question 15

…..inc peripheral decarboxylation of L-dopa

Answer 15

Pyridoxine

Question 16

Describe optimum diet for parkinson

Answer 16

Low in protein as aminoacids interfere with L-dopa metabolism
Fibers & fluid for constipation