CNS Meds: Parkinson's Disease Flashcards
Describe how Parkinson’s disease (PD) affects the body
- PD progressively affects a person’s ability to control movement
- PD also negatively impacts how a person feels, thinks, sleeps, and talks.
- Common symptoms
tremors, bradykinesia (slow movement), stiff muscles, stooped posture, etc.
Recall the effects of dopamine in the brain
- reward
- pleasure, euphoria
- motor function **
- compulsion
- perservation
Explain the role of the striatum in the brain
Corpus striatum is a part of the basal ganglia of the brain and coordinates movement of the body
Recite 2 parts of the brain that send information to the striatum
Striatum receives information from 2 sources:
neocortex & substantia nigra
Identify the part of the brain that delivers dopamine to the striatum
Substantia nigra
Substantia nigra neurons are an important source of dopamine for striatum
In PD, the neurons connecting the substantia nigra die – cutting off dopamine supply!
Describe the non-motor symptoms that a dopamine deficit causes
autonomic disturbances (quite a lot!)
depression
psychosis and dementia
flat affect
Discuss the neurotransmitter imbalance that leads to the symptoms of Parkinson’s disease
Parkinson’s is essentially imbalance!
Imbalance between dopamine (DOPA) and acetylcholine (Ach) in the brain –> not enough dopamine
Why dopamine is not directly given to Parkinson’s patients
Dopamine cannot cross the blood brain barrier
We can only give drugs that help increase dopamine levels in the brain or act like dopamine in the brain –> there are 6 types of Parkinson’s Drugs!!!
Explain how monoamine oxidase type B (MAO-B) inhibitors help restore dopamine levels
There will be less MAO-B
–> we can conserve dopamine in the brain
Explain how N-methyl-D-aspartate (NDMA) glutamate inhibitors help restore dopamine levels
NMDA-type glutamate blocker will block the action of glutamate to increase dopamine release
Explain how dopamine agonist inhibitors help restore dopamine levels
mimic dopamine and binds to dopamine receptors of neurons
Explain how dopamine prodrugs help restore dopamine levels
Levodopa (prodrug) can cross BBB and replaces missing dopamine in the brain
Explain how carbidopa decarboxylase inhibitors help restore dopamine levels
Carbidopa works by preventing levodopa from being broken down before it reaches the brain
Explain how catechol-O-methyltransferase (COMT) inhibitors help restore dopamine levels
COMT inhibitors act by blocking the action of enzymes that break down levodopa and extending the duration of its action in the brain
Explain how anticholinergics help restore dopamine levels
Anticholinergics block the activity of Ach
Select the best drug class for treating mild PD symptoms
MAO-B inhibitor
***conserve what you already have!
Select the drug class that is most effective for more severe PD symptoms
L-DOPA (combined with carbidopa)
Dopamine agonist
***when the symptoms get severe, we want to make more dopamine available!
How to manage times when medications “wear off” in Parkinson’s disease
“Off times” can be reduced with:
- dopamine agonists
- COMT inhibitors
- MAO-B inhibitors
Explain how levodopa increases dopamine levels in the brain of patients with Parkinson’s disease (PD)
Levodopa can cross BBB by active transport system in the brain
–> neurons in the striatum will uptake the levodopa
–> levodopa converted to dopamine in the striatum
Describe how carbidopa can maximize the effect of levodopa
Levodopa and carbidopa are like French fries & ketchup–they are better together!!
Although carbidopa cannot cross BBB, it can slow down the breakdown (decarboxylation) of levodopa in intestines
–> more L-DOPA can cross BBB, carbidopa reduces dosage of L-DOPA by 75%
Tell how the effects of levodopa and carbidopa change over time
Sadly, they are effective for the first 2 years, then decline after 3-5 years
Recall a common side effect of levodopa and carbidopa use
Patients can develop dyskinesia…
What do you need to teach patient and family when taking levodopa and carbidopa
Not to eat high protein meals with the medication
***dietary protein compete for protein transport across BBB
List CNS side effects of PD meds
- anxiety, agitation
- difficulty with memory or higher level thinking
- difficulty sleeping
- psychosis, hallucination
List behavioral side effects of PD meds
- impulsiveness
- loss of moral compass
- gambling, over-eating, alcohol abuse, etc.
List cardiovascular side effects of PD meds
risk of orthostatic hypotension (take adequate fluid and salt!)
irregular heartbeat or “fluttering (palpitation)”
Tell how levodopa affects the gastrointestinal (GI) tract
nausea and vomiting
**dopamine receptors on medulla get activated
Recall how levodopa and carbidopa affect the genitourinary (GU) system and skin
It can darken saliva, sweat, or urine
Also, it can active malignant melanoma –> patients should be screened for skin cancer regularly
List ways in which PD medication side effects can be reduced
- working with healthcare provider to adjust dosage
- take amantadine
- deep brain stimulation
List two dangerous drug interactions of levodopa, as well as its beneficial drug interaction
Dangerous: first generation antipsychotics, MAO inhibitors
Beneficial: anticholinergic medication
Describe the reasons it can be dangerous to administer 1st-generation antipsychotics with levodopa
FGA will block dopamine receptors in the striatum –> decrease therapeutic effects of L-DOPA.
Identify the potential risk of combining levodopa with monoamine oxidase inhibitors (MAOIs)
risk of developing hypertensive crisis
