Prescribing in the Elderly

Question 1

What environment is required for an acidic drug to be absorbed?

Answer 1

Acidic environment

pH < 7.35

Question 2

What are 3 examples of acidic drugs?

Answer 2

Phenytoin
Aspirin
Penicillin

Question 3

What environment is required for a basic drug to be absorbed?

Answer 3

Basic environment

pH > 7.35

Question 4

What are 3 examples of basic drugs?

Answer 4

Diazepam
Morphine
Pethidine

Question 5

How does gastric pH change with age?

Answer 5

Gastric pH rises with ageing.

Question 6

Why is gastric acidity lost with ageing?

Answer 6

Degeneration occurs of the parietal cells that produce HCl in the stomach.

Small bowel surface area also lost.

Question 7

In which individuals is the natural loss of gastric acidity an issue?

Answer 7

Those with previous GI surgery
Those with feeding that bypasses the stomach
Those with transdermal patches or with oedema present

Question 8

Are older patients at greater-risk of drug side-effects?

Answer 8

Yes,if the drug is basic - they absorb this more easily.

Question 9

Which molecule binds to acidic drugs?

Answer 9

Albumin

It itself is a basic molecule.

Question 10

Which molecule binds to basic drugs?

Answer 10

Alfa-1-acid glycoprotein

It itself is an acidic molecule.

Question 11

What are albumin levels usually like in elderly patients?

Answer 11

Usually low.

Question 12

What are alfa-1-acid glycoprotein levels usually like in elderly patients?

Answer 12

Usually raised.

Question 13

Is muscle mass greater in the elderly?

Answer 13

No, fat mass is greater.

Question 14

What does the increased fat mass of elderly people do for lipophilic drugs?

Answer 14

Increases their volume of distribution.

Question 15

What is volume of distribution?

Answer 15

A theoretical volume into which a drug is fully dissolved in the plasma.

Indicates how long a drug will stay in the body.

Question 16

What is half-life?

Answer 16

The time-taken for drug concentration to fall to half of its maximal concentration.

Question 17

Do lipophilic drugs have a long half-life in elderly people?

Answer 17

Yes, as they have more fat, meaning the drug will stay around for longer.

Question 18

What is first-pass metabolism?

Answer 18

Where a drug is greatly reduced prior to reaching circulation due to processing within the liver.

This is where most drugs are metabolised.

Question 19

How does ageing affect first-pass metabolism?

Answer 19

Ageing reduces the ability of first-pass metabolism.

Question 20

How does ageing affect GFR?

Answer 20

GFR drops.

Caused by decreased tubular secretions, size and renal bloodflow.

Question 21

Is serum creatinine a reliable measure?

Answer 21

No, only indicates muscle mass.

Use creatinine clearance instead.

Question 22

How is therapeutic index calculated?

Answer 22

50% of lethal dose/50% of effective dose

Question 23

What should be given alongside opioids prophylactically, in order to prevent constipation?

Answer 23

Laxatives

Question 24

What should not be given alongside levothyroxine?

Answer 24

Calcium supplementation - will impact absorption.

Question 25

Is paracetamol as effective as NSAIDs in treating mild pain?

Answer 25

Yes

Question 26

What are side-effects of NSAIDs in the elderly?

Answer 26

Reduced effectiveness of diuretics and antihypertensives
Increased risk of GI haemorrhage
Reduced GFR

Question 27

Should NSAIDs be given in the elderly?

Answer 27

No, avoid where possible.

Question 28

How should opioids and benzodiazepines be prescribed in the elderly?

Answer 28

Give at the lowest dose possible for the shortest period of time.

Question 29

What are side-effects commonly seen in opioids and benzodiazepines?

Answer 29

Psychomotor dysfunction resulting in falls and confusion.

Question 30

What are the 4C’s of c.difficile?

Answer 30

Ciprofloxacin
Co-amoxiclav
Clindamycin
Cephalosporins