EXAM #5: GERIATRIC PHARMACOLOGY

Question 1

What are four methods to achieve successful pharmacotherapy in the geriatric population/ prevent the prescribing cascade.

Answer 1

1) Avoid prescribing new drugs until tests confirm diagnosis
2) Start low and titrate up
3) Avoid starting or changing multiple medications at once
4) Reach TD before switching or adding new agents

Question 2

What are the tools used to evaluate appropriate medication use in the elderly?

Answer 2

1) Beers List
2) STOPP
3) START

• STOPP= Screening Tool of Older Persons’ potentially inappropriate Prescriptions
• START= Screening Tool to Alter doctors to Right Treatment

Question 3

What body composition changes in the elderly can result in altered pharmacokinetics?

Answer 3

1) Decreased TBW
2) Decreased lean body mass
3) Increased body fat

Question 4

What cardiovascular changes in the elderly can result in altered pharmacokinetics?

Answer 4

1) Decreased sensitivity to B-adrenergic stimulation
2) Decreased baroreceptor activity
3) Decreased CO
4) Increased TPR

Question 5

What liver changes in the elderly can result in altered pharmacokinetics?

Answer 5

1) Decreased hepatic size

2) Decreased hepatic blood flow

Question 6

What renal changes in the elderly can result in altered pharmacokinetics?

Answer 6

1) Decreased GFR
2) Decreased RBF
3) Decreased filtration fraction
4) Decreased tubular secretory function
5) Decreased renal mass

Question 7

What happens to first pass metabolism with aging?

Answer 7

Less first pass metabolism

Question 8

What happens to drug distribution with aging?

Answer 8

Differences in body composition lead to altered distribution

Question 9

What happens to drug metabolism and clearance with aging?

Answer 9

Reduced liver and kidney function/ blood flow impairs metabolism and clearance

Question 10

What are the implications of less first pass metabolism in the geriatric population?

Answer 10

1) LOWER dose requirements for drugs INACTIVATED by first pass metabolism
2) HIGHER dose requirements for PRODRUGS that require first pass metabolism for activation

Question 11

What does a large Vd indicate?

Answer 11

Most of the drugs DISTRUBUTES to the extravascular compartment

Question 12

How is Vd altered in the elderly? What will happen with the adminstration of a lipophilic drug?

Answer 12

High fat mass and low lean body mass INCREASE the Vd

Thus, there is an increased Vd in the elderly–especially with lipophillic drugs

Question 13

What is the effect of lower TBW in the elderly in regards to water soluble drugs?

Answer 13

Less TBW= lower Vd (more drug stays intravascular)

Question 14

How does a large Vd affect the half-life of a lipid-soluble drug? Give an example of a drug that follows this pattern.

Answer 14

A large Vd INCREASES the half-life

*Digoxin

Question 15

How does a low Vd of a water soluble drug alter the loading dose? Give an example of a drug that follows this pattern.

Answer 15

Loading dose would be DECREASED to prevent toxicity

*Genatmicin

Question 16

What is drug clearance? What is the equations for clearance?

Answer 16

Rate of elimination of a drug

CL= Q (flow) x E(extraction)

Question 17

What are the two major organs are involved in drug clearance?

Answer 17

Liver

Kidneys

Question 18

How is hepatic clearance altered in elderly patients?

Answer 18

1) Decreased flow to liver
2) Decreased liver metabolism/ extraction
- Phase I enzymes have REDUCED activity (CYP p450)

Thus, reduced drug clearance

Question 19

Which phase of liver metabolism is most affected by aging?

Answer 19

Phase I i.e. CYP p450

Question 20

What is a capacity-limited drug? What are the implications in the elderly?

Answer 20

Rate-limiting step in clearance is liver enzymes (vs. flow)

There will be decreased clearance of a capacity-limited drug if metabolized by Phase I enzymes

Question 21

What is a flow-rate limited drug? What are the implications in the elderly?

Answer 21

Rate-limiting step in clearance is hepatic blood flow

All drugs that are flow limited will have decreased clearance in the elderly

Question 22

What are the implications of less drug clearance on maintenance dosing the the elderly?

Answer 22

Generally, less maintenance doses are needed to maintain a steady state drug concentration

Question 23

What is the exception to changes in maintenance doses seen in the elderly?

Answer 23

No change seen in capacity-limited, phase II metabolized drugs

Question 24

Why is renal excretion decreased in the elderly?

Answer 24

1) Decreased GFR

2) Polypharmacy causes competition at tubular transporters

Question 25

Generally, what is the marker used to determine GFR?

Answer 25

Creatinine

Question 26

What is creatinine directly proportional to?

Answer 26

Lean muscle mass

Question 27

How does creatinine change in elderly patients?

Answer 27

Less lean body mass= less creatinine

Question 28

What is the Cockcroft and Gault equation?

Answer 28

Equation that accounts for decreased muscle mass in elderly when calculating GFR based on creatinine

Question 29

How do decreased hepatic and renal drug clearance in elderly patients alter the T1/2? What type of drug will see the largest change?

Answer 29

• Decreased clearance INCREASES half-life

- Lipophilic drugs have further increases in half-life b/c of increased Vd

Question 30

What do you need to keep in mind about NSAIDs in the elderly?

Answer 30

Elderly patients are highly susceptible to toxicity of NSAIDs

Question 31

Explain how NSAIDs can lead to renal damage in the elderly.

Answer 31

• RBF is reduced in elderly
• PGs are secreted to maintain blood flow/GFR
• NSAIDs BLOCK PGs

Question 32

What can the effects of anticholinergic drugs lead to in the elderly?

Answer 32

Overall functional decline from:

1) Falls
2) Impaired congnition

Question 33

What drug classes have anticholinergic activity that may lead to functional decline in the elderly?

Answer 33

Anticonvulsants 
Antidepressants 
Antihistamines 
Antipsychotics 
CV 
GI/GU antispasmodics
H2 antagonists 
Muscle relaxants 
PD drugs 
Vertigo