CNS Meds: Parkinson's Disease

Question 1

Describe how Parkinson’s disease (PD) affects the body

Answer 1

• 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.

Question 2

Recall the effects of dopamine in the brain

Answer 2

• reward
• pleasure, euphoria
• motor function **
• compulsion
• perservation

Question 3

Explain the role of the striatum in the brain

Answer 3

Corpus striatum is a part of the basal ganglia of the brain and coordinates movement of the body

Question 4

Recite 2 parts of the brain that send information to the striatum

Answer 4

Striatum receives information from 2 sources:

neocortex & substantia nigra

Question 5

Identify the part of the brain that delivers dopamine to the striatum

Answer 5

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!

Question 6

Describe the non-motor symptoms that a dopamine deficit causes

Answer 6

autonomic disturbances (quite a lot!)
depression
psychosis and dementia
flat affect

Question 7

Discuss the neurotransmitter imbalance that leads to the symptoms of Parkinson’s disease

Answer 7

Parkinson’s is essentially imbalance!

Imbalance between dopamine (DOPA) and acetylcholine (Ach) in the brain –> not enough dopamine

Question 8

Why dopamine is not directly given to Parkinson’s patients

Answer 8

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!!!

Question 9

Explain how monoamine oxidase type B (MAO-B) inhibitors help restore dopamine levels

Answer 9

There will be less MAO-B
–> we can conserve dopamine in the brain

Question 10

Explain how N-methyl-D-aspartate (NDMA) glutamate inhibitors help restore dopamine levels

Answer 10

NMDA-type glutamate blocker will block the action of glutamate to increase dopamine release

Question 11

Explain how dopamine agonist inhibitors help restore dopamine levels

Answer 11

mimic dopamine and binds to dopamine receptors of neurons

Question 12

Explain how dopamine prodrugs help restore dopamine levels

Answer 12

Levodopa (prodrug) can cross BBB and replaces missing dopamine in the brain

Question 13

Explain how carbidopa decarboxylase inhibitors help restore dopamine levels

Answer 13

Carbidopa works by preventing levodopa from being broken down before it reaches the brain

Question 14

Explain how catechol-O-methyltransferase (COMT) inhibitors help restore dopamine levels

Answer 14

COMT inhibitors act by blocking the action of enzymes that break down levodopa and extending the duration of its action in the brain

Question 15

Explain how anticholinergics help restore dopamine levels

Answer 15

Anticholinergics block the activity of Ach

Question 16

Select the best drug class for treating mild PD symptoms

Answer 16

MAO-B inhibitor

***conserve what you already have!

Question 17

Select the drug class that is most effective for more severe PD symptoms

Answer 17

L-DOPA (combined with carbidopa)

Dopamine agonist

***when the symptoms get severe, we want to make more dopamine available!

Question 18

How to manage times when medications “wear off” in Parkinson’s disease

Answer 18

“Off times” can be reduced with:

• dopamine agonists
• COMT inhibitors
• MAO-B inhibitors

Question 19

Explain how levodopa increases dopamine levels in the brain of patients with Parkinson’s disease (PD)

Answer 19

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

Question 20

Describe how carbidopa can maximize the effect of levodopa

Answer 20

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%

Question 21

Tell how the effects of levodopa and carbidopa change over time

Answer 21

Sadly, they are effective for the first 2 years, then decline after 3-5 years

Question 22

Recall a common side effect of levodopa and carbidopa use

Answer 22

Patients can develop dyskinesia…

Question 23

What do you need to teach patient and family when taking levodopa and carbidopa

Answer 23

Not to eat high protein meals with the medication

***dietary protein compete for protein transport across BBB

Question 24

List CNS side effects of PD meds

Answer 24

• anxiety, agitation
• difficulty with memory or higher level thinking
• difficulty sleeping
• psychosis, hallucination

Question 25

List behavioral side effects of PD meds

Answer 25

- impulsiveness - loss of moral compass - gambling, over-eating, alcohol abuse, etc.

Question 26

List cardiovascular side effects of PD meds

Answer 26

risk of orthostatic hypotension (take adequate fluid and salt!) irregular heartbeat or "fluttering (palpitation)"

Question 27

Tell how levodopa affects the gastrointestinal (GI) tract

Answer 27

nausea and vomiting **dopamine receptors on medulla get activated

Question 28

Recall how levodopa and carbidopa affect the genitourinary (GU) system and skin

Answer 28

It can darken saliva, sweat, or urine Also, it can active malignant melanoma --> patients should be screened for skin cancer regularly

Question 29

List ways in which PD medication side effects can be reduced

Answer 29

- working with healthcare provider to adjust dosage - take amantadine - deep brain stimulation

Question 30

List two dangerous drug interactions of levodopa, as well as its beneficial drug interaction

Answer 30

Dangerous: first generation antipsychotics, MAO inhibitors Beneficial: anticholinergic medication

Question 31

Describe the reasons it can be dangerous to administer 1st-generation antipsychotics with levodopa

Answer 31

FGA will block dopamine receptors in the striatum --> decrease therapeutic effects of L-DOPA.

Question 32

Identify the potential risk of combining levodopa with monoamine oxidase inhibitors (MAOIs)

Answer 32

risk of developing hypertensive crisis