Principles of prescribing and deprescribing in the elderly

Question 1

Does increasing in age alter drug pharmacokinetics?

Answer 1

Yes

Question 2

As age increases, how is absorption of drugs generally affected?

Answer 2

As age increases, drug absorption decreases

Question 3

Why does reduced intestinal blood flow decrease drug absorption?

Answer 3

Less drugs can be absorbed into systemic bloodstream/circulation

Question 4

Define gastrointestinal (GI) motility

Answer 4

Coordinated contractions and relaxations of the muscles of the GI tract necessary to move contents from the mouth to the anus

Question 5

As age increases, how is GI motility affected?

Answer 5

Reduced GI motility

Question 6

Which route of drug administration is most affected by GI motility?

Answer 6

Oral

Question 7

What gastric mechanism is regulated by GI motility, that is the major factor as to why GI motility reduces drug absorption in elderly people?

Answer 7

Gastric emptying rate

Slow rate means that drug stays in stomach for longer so much less of drug will be absorbed

Question 8

Give 3 reasons why having a slow gastric emptying rate reduces drug absorption?

Answer 8

Stomach has much smaller surface area than bowels, which is where drug absorption is high

Lower gastric pH which can decrease solubility of drugs

Stomach lining coated with thick mucus so less diffusion of drug into bloodstream occurs

Question 9

How does gastric emptying rate change as age increases, and what is the general overlying reason?

Answer 9

As age increases, gastric emptying rate decreases

Because gastric emptying rate is regulated by GI motility, which is reduced by old age

Question 10

Define drug distribution (pharmacokinetics)?

Answer 10

Movement of drug into body tissues

Question 11

As age increases, how does the concentration of plasma proteins that can bind to drugs change, and how can this lead to drug toxicity?

Answer 11

Concentration decreases

So more unbound/active drugs in bloodstream, so can be distributed more easily: increased effects and drug toxicity

Question 12

As age increases, why are more lipid-soluble and less water-soluble drugs distributed to body tissues?

Answer 12

Reduced total water volume, so less water-soluble drugs are distributed

More total body fat, so more lipid-soluble drugs are distributed

Question 13

What metabolic process is reduced due to decreased hepatic blood flow as age increases, and why?

Answer 13

As age increases, hepatic blood flow decreases so less active drugs can be transported from GI tract to liver to allow first-pass metabolism

Question 14

Other than reduced hepatic blood flow, why is first-pass metabolism decreased as age increases?

Answer 14

Liver enzyme function decreases as age increases

Less first-pass reactions can be catalysed

Question 15

How can decreased first-pass metabolism of liver cause drug toxicity, in elderly people?

Answer 15

First-pass metabolism decreases, so more active drugs absorbed into circulation with high bioavailability, which can increase toxicity

Question 16

Why is drug excretion decreased as age increases, and what harmful effect does this have?

Answer 16

Renal function decreases with age (usually after 40 yrs old)

which can lead to build up of toxic levels of drugs

Question 17

After which age does renal function tend to decrease?

Answer 17

After 40 years old

Question 18

How are drug pharmacodynamics affected by increasing age?

Answer 18

As age increases, drug pharmacodynamic effects are larger/smaller

Question 19

Give 4 physiological causes why altered drug pharmacodynamics result from increasing age?

Answer 19

Drug-receptor interaction

Post receptor events

Adaptive homeostatic responses

Pathologic changes in organs (in frail patients)

Question 20

Which 3 body systems most commonly have altered pharmacodynamic effects of drugs, as age increases?

Answer 20

CNS
GI
Cardiovascular

Question 21

What problem can occur when using drug dosage for younger patients to determine the correct dosage of that drug to prescribe to an elderly patient?

Answer 21

Drug dosages for young patients not accurately extrapolated, so elderly patients are prescribed dosage that can be toxic

Question 22

Define polypharmacy?

Answer 22

simultaneous use of multiple medicines by a patient

Question 23

Why is polypharmacy more common in elderly patients, and what 2 interactions due to polypharmacy have increased risk in elderly patients?

Answer 23

Increased prevalence of co-morbidities which often results in polypharmacy

increases drug-disease and drug-drug interactions

Question 24

Define drug-disease interaction, and what problem it can commonly lead to in elderly patients?

Answer 24

Pharmacotherapy used to treat a disease causes adverse effect of another disease in a patient

Causes prescription cascade: New drug prescribed to treat adverse effect of a disease, as the adverse effect is misinterpreted as a symptom of a new disease

Question 25

Define prescription cascade?

Answer 25

New drug prescribed to treat adverse effect of a disease, as the adverse effect is misinterpreted as a symptom of a new disease

Question 26

Give 3 reasons why less concordance with treatment due to decreasing patient adherence can occur, especially in elderly patients?

Answer 26

Reluctance due to :
pre-existing polypharmacy

not understanding drug mechanisms

cognitive impairment

Question 27

What pharmacological therapy framework was produced by the Department of Health, to safely prescribe for elderly patients?

Answer 27

Medicines for Older People document

From: National Service Framework for Older People

Question 28

Give 2 guidance tools that can be used to prevent drug-drug and drug-disease interactions, to safely prescribe for elderly patients?

Answer 28

A-Z interactions in BNF

STOPP (Screening Tool of Older Persons’ potentially inappropriate Prescriptions) criteria

Question 29

What does STOPP criteria mean, and what is its function?

Answer 29

Screening Tool of Older Persons’ potentially inappropriate Prescriptions

Evidence-based criteria to prevent drug-drug and drug-disease interactions

Question 30

What does START criteria mean, and what is its function?

Answer 30

Screening Tool to Alert to Right Treatment

Evidence-based criteria to prevent omissions of indicated, appropriate medicines in older patients with specific conditions

Question 31

How should you start and adjust drug dosage, to safely prescribe for elderly patients?

Answer 31

Start with lowest effective dose and uptitrate if needed

Question 32

How can you increase concordance with treatment and patient adherence, to safely prescribe for elderly patients?

Answer 32

Provide clear instructions to patient on how to administer drug, purpose

avoid confusion by pointing out similar names of other drugs

Question 33

Define deprescribing, and its 2 general purposes?

Answer 33

Safe withdrawal of medicines that are no longer appropriate, beneficial or wanted (patient preference)

to improve quality of life and reduce unnecessary treatments

Question 34

In which type of care is deprescribing especially used?

Answer 34

Palliative care

Question 35

To safely deprescribe for elderly patients, who needs to review the changing needs of the patient?

Answer 35

Regular review with all specialties to meet needs of patient as they change

Question 36

To safely deprescribe for elderly patients, is patient consent needed?

Answer 36

Yes

Agree with patient and their important contacts to taper medications that are not providing symptomatic benefit, causing harm or are unnecessary⁽