Chapter 21 - Drugs for Parkinson's Disease

Question 1

Parkinson’s Disease - def

Answer 1

a disorder of the extrapyramidal system associated with disruption of neurotransmissions within the striatum.

Question 2

Parkinson’s results in….

Answer 2

Dyskinesias - a disorder of movement.

Question 3

Parkinson’s affects over ____ American.

Answer 3

one million.

Question 4

Symptoms of Parkinson’s -

Answer 4

tremors, rigidity, postural instability, bradykinesia (slowed movement), psychological disturbances (loss of cognitive ability, depression, impaired memory.)

Question 5

What is the cause of Parkinson’s?

Answer 5

Loss of dopaminergic neurons in substantia nigra.

Question 6

Dopamine and GABA are inhibitory or excitatory?

Answer 6

Inhibitory

Question 7

ACH is inhibitory or excitatory?

Answer 7

Excitatory.

Question 8

What is the therapeutic goal of Parkinson’s Treatment?

Answer 8

Improve activities of daily living, because drugs can’t cure it - just try and get rid of the seconds.

Question 9

Treatment strategy - Parkinson’s disease.

Answer 9

Regain balance of dopamine and ACH, by using agents that directly or indirectly activate dopamine receptors. You can also use agents that block ACH receptors.

Question 10

What are the two major categories of drugs that treat PD?

Answer 10

Dopaminergic agents and Anticholinergic Agents.

Question 11

Dopaminergic agents - def

Answer 11

promote activation of dopamine receptors. - Levodopa (Dopar.)

Question 12

Anticholinergic Agents - def

Answer 12

prevent activation of cholinergic receptors. - Benzotropine (Cogentin.)

Question 13

Dopaminergic Agents can….4

Answer 13

Promote dopamine synthesis, promote dopamine release, directly activate dopamine receptors, prevent dopamine degradation.

Question 14

Anticholinergic drugs can…1

Answer 14

Block muscarinic cholinergic receptors in the striatum.

Question 15

What are some Dopaminergic Drugs? (6)

Answer 15

Levodopa, Carbidopa, Amantadine, Selegiline, Bromocriptine, Bromocriptine, Pergolide

Question 16

Levodopa - what does it do?

Answer 16

increase synthesis of dopamine.

Question 17

Carbidopa - what does it do?

Answer 17

Inhibits peripheral decarboxylase enzyme, hence reduce degradation of Dopamine.

Question 18

Amantadine and Selegiline - what do they do?

Answer 18

Promote release of dopamine

Question 19

Bromocriptine and Pergolide - what do they do?

Answer 19

They activate dopamine receptors.

Question 20

Anticholinergic Drug - 1 - and what does it do?

Answer 20

Benzotropine - Blocks ACH receptors.

Question 21

What is a major side effect of Anticholinergic drugs?

Answer 21

Xerostomia - dry mouth.

Question 22

Are levodopa and carbidopa combined in treatment?

Answer 22

Yes.

Question 23

What is the drug of choice for PD treatment?

Answer 23

Levadopa.

Question 24

If a patient fails to respond to levodopa, then what should happen?

Answer 24

We should ask ourselves rather or not PD is the correct diagnosis.

Question 25

It only takes weeks to respond to levodopa - T/F?

Answer 25

FALSE. It may take months.

Question 26

How can we minimize the gradual loss/wearing off of Levodopa? 3

Answer 26

Shorten the dose interval, give drug that increases the half-life (tocapone) and give a direct acting dopamine agonist.

Question 27

We should eat a shit ton of protein with Levodopa - T/F?

Answer 27

NO! That could cause it! So avoid it!

Question 28

What’s the MOA for Levodopa ?

Answer 28

Enters brain by active transport –> taken up by the few remaining dopaminergic nerve terminals that remain –> converted to dopamine by enzyme decarboxylase, which is enhanced by pyridoxine - vitamin B6!! –> balance ACH

Question 29

Levodopa - Pharmacokinetics

Answer 29

Administered orally and rapidly from small intestine, and food delays absorption. Only 2% of dose reaches brain because decarboxylase enzyme metabolizes it.

Question 30

Levodopa - side effects.

Answer 30

Nausea, vomitting, Dyskinesias, Hypotension, Psychosis

Question 31

Drug interactions for Levodopa -

Answer 31

don’t mix it with antipsychotic drugs (drugs that block dopamine receptors), MAO inhibitors, anticholinergic drugs, or foods with high protein.

Question 32

Carbidopa has a ton of adverse effects - T/F?

Answer 32

False! None

Question 33

Why is PD not treated with straight up dopamine? 2 Reasons.

Answer 33

Dopamine cannot cross the Blood brain barrier and it has a short half life.