CNS Agents Flashcards
what drugs are a part of CNS pharmacology?
opioids
anti-parkinsonism meds
psychopharmacology
antiepileptic meds
anti-spasmodic meds
PD causes a decrease in ___ and an increase in ____ influence
dopamine, acetylcholine
what happens with damage to the substantia nigra?
death of dopamine producing cells (PD)
t/f: in PD the amount of ACh is not increased, but it’s relative influence is increased
true
pharmacology for PD increases ____ or takes away ____
dopamine, Ach
what are the 3 classifications of anti-parkinson agents?
carbidopa/Levodopa 25/100 (Sinemet 25/100): dopamine replacement
pramipexole (Mirapex): dopamine agonist
rasagiline (Azilect): monoamine oxidase-B (MOAB) inhibitor
what is Levodopa (l-dopa)?
dopamine replacement
precursor to dopamine
attempts to increase dopamine levels in the basal ganglia
what kind of drug is carbidopa/Levodopa?
a dopamine replacement
what kind of drug is pramipexole?
dopamine agonist
what kind of drug is rasagiline?
monoamine oxidase-B (MOAB) inhibitor
why can’t dopamine be used to treat PD?
bc dopamine can’t cross the blood brain barrier (BBB)
what converts L-dopa into dopamine?
DOPA (decarboxylase)
why is carbidopa given with l-dopa?
bc l-dopa can be converted into dopamine in the periphery before it reaches the brain, so it still won’t be able to cross the BBB.
carbidopa prevents the premature transformation of L-dopa to dopamine before crossing the BBB by inhibiting decarboxylase in the periphery
what pill combines L-dopa and carbidopa?
Sinemet
what is pramipexole?
a dopamine agonist that binds and activates dopaminergic receptors in the striatum
boosts the action of available dopamine
given earlier in disease progression
what drugs fall under the category of promipexole (Mirapex)?
Rotigotine (Neupro)
Apomorphine (Apokyn)
what is Rasagiline (Azilect)?
a MOAB inhibitor that reduces the breakdown of dopamine, resulting in increased levels of dopamine in the brain
often used with L-dopa
will Rasagiline (azilect) be effective if the brain is depleted of all dopamine?
no
t/f: the use of Rasagiline with L-dopa can decrease the dose of L-dopa required
true
why is it beneficial that Rasagiline with L-dopa can reduce the dose of L-dopa required?
bc L-dopa has a lot of side effects and if a long-term drug
t/f: Rasagiline has a lot of side effects
false, Rasagiline has relatively few side effects
what is Selegiline (Eldepryl)?
a non-selective MAOI
also used as an antidepressant bc it can stop the breakdown of other NTs like serotonin
what is the desired therapeutic effect of carbidopa/Levodopa (sinemet)?
more dopamine in the brain–> more movement
what is the desired therapeutic effect of pramipexole (Mirapex)?
activate dopamine receptors in the brain–>more movement
what is the desired therapeutic effect of rasagiline (azilect)?
less dopamine broken down in the brain–>more movement
when is the peak plasma concentration of carbidopa/Levodopa (sinemet)?
0.5-2 hours
when is the peak plasma concentration of pramipexole (mirapex)?
1-3 hours
when is the peak plasma concentration of rasagiline (azilect)?
0.5-1 hour
what is the half life of carbidopa/Levodopa (sinemet)?
1.5 hours
what is the half life of pramipexole (Mirapex)?
8-12 hours
what is the half life of rasagiline (azilect)?
1.5-3.5 hours
t/f: carbidopa/Levodopa (sinemet) has minimal hepatic metabolism
true
t/f: pramipexole (Mirapex) has minimal hepatic metabolism
true
t/f: rasagiline (azilect) has minimal hepatic metabolism
false, it has extensive hepatic metabolism
what are common side effects of carbidopa/levodopa (sinemet)?
orthostatic hypotension, confusion, movement disorders, nausea, hallucinations
what are common side effects of pramipexole (mirapex)?
inappropriate urges (sexual, gambling, etc), edema (usually peripheral below the knees)
t/f: pramipexole (mirapex) can be used to treat restless leg syndrome
true
what are common side effects of rasagiline (azilect)?
headache, nausea, joint pain, upset stomach, depression, falls, constipation, orthostatic hypotension, dry mouth, rash, hallucinations, vomiting, and difficulty moving
t/f: there are a lot of movement and behavioral side effects of meds targeting dopaminergic receptors
true
t/f: meds with overlapping side effects make those side effects more likely
true
what is a very common side effect of PD meds
dyskinesia (unwanted movement)
t/f: orthostatic hypotension is already a symptom of PD, so PD meds may make it worse as it is a common side effect
true
are hallucinations associated with PD meds usually visual or auditory?
visual
t/f: hallucinations from PD meds can cause psychosis like symptoms
true
what are serious side effects of carbidopa/levodopa (sinemet)?
dyskinesia
orthostatic hypotension
MI
arrhythmias/depression
what are serious side effects of pramipexole (mirapex)?
hallucinations, vision changes, SOB/chest pain
ongoing safety review regarding possible risk of heart failure
why is it especially important to monitor cardiac symptoms if a pt is on pramipexole (mirapex)?
bc there is a risk for heart failure
what are serious side effects of rasagiline (azilect)?
HTN
MI
arryhthmias
dyskinesia
what is a potential drug interaction with carbidopa/Levodopa (sinemet)?
MAOI antidepressants with carbidopa/Levodopa can severely increase BP
protein with carbidopa/levodopa can have negative interactions
why should carbidopa/Levodopa (sinemet) be taken at least an hour after a meal (especially high protein meals)?
bc it can have negative interactions with protein
what are potential drug interactions with pramipexole (mirapex)?
acetaminophen, aspirin, caffeine, opioid analgesics can increase the side effects of pramipexole (mirapex)
what are potential drug interactions with rasagiline (azilect)?
antidepressants that increase serotonin levels can lead to serotonin syndrome
amphetamines (stimulants)
vasoconstrictors
interactions lead to an increased risk of CV events
what are the symptoms associated with serotonin syndrome?
arrhythmias, seizures, confusion, increased reflexes, dilated pupils, etc)
what is the on-off phenomenon?
motor symptoms fluctuate w/in dose cycle of PD meds
end-of-dose akinesia/dyskinesia
peaks (side effects) and valleys (no therapeutic effect)
decreased therapeutic window after prolonged drug use
what can we do for a pt experiencing symptoms of the on-off phenomenon?
decrease dosage, increase frequency
give dif drug with dif action
powder form of l-dopa can be inhaled for the off periods to get them through until the next dose (when in the valley)
what are other classes of drugs commonly used for PD?
anticholinergics
COMT inhibitors
NMDA receptor blockers
what do anticholinergic drugs do?
combat the increased influence of Ach
decrease excessive movement (rigidity and tremors and drooling)
what kind of drugs are Trihexyphenidyl (artane), Benztropine (cogentin), and Biperiden (Akineton)?
anticholinergic
what are the side effects of anticholinergic drugs?
dry mouth, blurred vision, photophobia, urinary retention, constipation
are the side effects of anticholinergic drugs related to sympathetic or parasympathetic overactivation?
sympathetic overactivation
anticholinergic drugs down regulate ____ and up regulate ____
parasympathetic, sympathetic
what is COMT (catechol-O-methyltransferase)?
an enzyme that breaks down L-dopa in peripheral tissues
what do COMT inhibitors do?
prevent L-dopa from breaking down in the periphery by blocking COMT
similar actions to carbidopa
what kind of drugs are Tolcapone (Tasmar) and Entacapone (Comtan)?
COMT inhibitors
t/f: COMT inhibitors can be combined with l-dopa and carbidopa
true
what drug is a combo of COMT inhibitors, L-dopa, and carbidopa?
Stalevo
what are the side effects of COMT inhibitors?
abdominal pain, back pain, constipation, nausea, diarrhea, and hematuria (blood in urine)
NMDA receptors are a subtype of ___ receptors, which are ___?
glutamate, excitatory
what do NMDA receptor blockers do?
the exact mechanism is unknown but it is believed to increase dopamine release or decrease glutamate influence
what type of drug is Amantadine (symmetrel, Gocoril)?
NMDA receptor blockers
t/f: Amantadine is an antidyskinetic agent, NMDA antagonists, dopamine agonist, and anticholinergic
true
what does NMDA receptor blockers treat?
tremors and dyskinesia
t/f: NMDA receptor blockers are given in conjunction with Levodopa in pts with excessive movements like tremors
true
what are the side effects of NMDA receptor blockers?
orthostatic hypotension, depression, confusion, rashes
what are the PT implications of CNS agents?
scheduling of PT
recognize synergistic effects of physical rehab and drug therapy
pt education
pt safety
advocacy
when should PT be scheduled for a pt with PD?
30-60 minutes after meds are taken
may see pts in off periods
what can we educate pts on?
dosing schedule
keeping an hourly log of symptoms
what pt safety risks should we keep in mind?
OH, falls, syncope
how can we advocate for our pts?
document responses and side effects to med changes
communicate with the pt and neurologist for optimizing meds
