parkinson drug Flashcards
what does levodopa do? MOA
It is a dopamine precursor, converted to dopamine in cns. After conversion, it acts as neurotransmitter dopamine which relieves PD symptoms.
adverse effects of levodopa
Short term: n/v, postural hypotension
Long term: motor fluctuations, dyskinesia ( too much dopamine, no good regulation of it) 10% increase risk per year, it will stay even if u stop taking levodopa, usual episode is 40 mins:(
indication of parkinson
Increase dopamine synthesis
what is 2 in 1 preparation
-”2 in 1” preparation with peripheral decarboxylase inhibitors to help Levodopa to be converted to dopamine only in the brain, helps levodopa to cross the blood brain barrier easily. Eg. levodopa + carbidopa=sinemet. Or madopar.
examples of Catechol-O-methyltransferase (COMT) inhibitors,
*Entacapone
Tolcapone
indication of COMT, entacapone, tolcapone
inhibit dopamine breakdown
MOA of entacapone, tolcapone
COM Blocks an enzyme that converts levodopa into an active form. By inhibiting COM, more levodopa is available to enter the brain
Increases duration of levodopa, beneficial in treating ‘wearing off” responses.
side effects of COMT
-dyskinesia
-n/v
-urinary discolouration (orange brown/ rust coloured)
-visual hallucinations
-daytime drowsiness, sleep disturbances
*Tolcapone- liver dysfunction
Are entacapone, tolcapone effective when taken alone?
no , -it is only effective when taken with levodopa
indication of Selegiline
mild parkinson activity
example of MAO-B inhibitors,
Selegiline
MOA of selegiline, MAO B I
Inhibits enzyme monoamine oxidase B, which interferes with breakdown of dopamine. MAO-B I may delay the nigral brain cell degeneration.
adverse effect of MAO- B I
-heartburn
-LOA
-nausea
-constipation
-dizziness
-anxiety, palpitation
-headache
-insomnia, nightmares
-confusion
-visual hallucination
Can selegiline be taken alone?
*It is effective as a symptomatic monotherapy and may be used in early stages of parkinson’s disease
example of Anticholinergic medication
trihexyphenidyl
Adverse effects of trihexyphenidyl
-dry mouth
-constipation, urinary retention
-sedation, delirium, confusion, hallucination
what is trihexyphenidyl effective for?
controlling tremors, sialorrhoea
can anticholinergic trihexyphenidyl be used alone?
- may be used as symptomatic monotherapy or adjunct to levodopa to treat tremors and stiffness in PD.
side effects of dopamine agonist
– similar to levodopa
– ‘ergot’ derivative - fibrosis
– pedal edema
– somnolence with ropinirole, pramipexole
– arrhythmia
– Pergolide - restrictive valvular heart disease
Can dopamine agonists be taken alone?
Dopamine agonists are efficacious as
symptomatic monotherapy. Dopamine agonists
may also be used as an adjunct to levodopa in
the treatment of Parkinson’s disease
should younger patients focus on taking levodopa or dopamine agonist?
In younger Parkinson’s disease patients,
therapy should commence first with dopamine
agonists rather than levodopa.
