Therapeutics- Prescribing in Special Groups- Old People

Question 1

What is physiological ageing?

Answer 1

Time-related loss of functional units within an organ system (e.g. nephrons, neurones)

Question 2

What is frailty?

Answer 2

Progressive physiological decline in multiple organ systems results in loss of physiological reserve and increased vulnerability to death and disease

Question 3

What is polypharmacy?

Answer 3

Concurrent use of multiple medications- typically defined as more than 4

Question 4

What changes affect the absorption of drugs in the elderly?

Answer 4

Decreased gastric motility
Decreased gastric blood supply and regional blood supply
Decreased saliva production
Increased gastric pH

Question 5

How does first pass metabolism change in the elderly?

Answer 5

Decreases due to reduced hepatic blood flow

Question 6

How does body fat change with age?

Answer 6

It increases- causing the Vd for lipid soluble drugs to increase
Diazepam is an example of a lipid soluble drug

Question 7

How does body water change with age?

Answer 7

It decreases- causing the Vd of water soluble drugs to decrease so concentrations can increase

Question 8

How does plasma protein concentration change with age?

Answer 8

Plasma protein concentration reduces- meaning the concentration of free drug can be higher. E.g. Phenytoin (used for epilepsy)

Question 9

How does drug metabolism change with increasing age?

Answer 9

Reduced activity of cytochrome P-450 reduces the metabolism of some drugs. This causes reduced metabolic clearance and reduced activation of pro-drugs

Question 10

How does elimination change with increasing age?

Answer 10

Renal function reduces with age so there is reduced clearance of renally excreted drugs

Question 11

What are the geriatric giants?

Answer 11

Instability
Immobility
Impaired Intellect/Memory
Incontinence

Question 12

What is the STOPP/START Criteria?

Answer 12

Used to decide wether to add or remove medications for elderly people

Question 13

What drugs should be avoided with renal impairment?

Answer 13

NSAIDs
Amino glycosides- Gentamicin
Metformin- Increased risk of lactic acidosis
Nitrofurantoin- Not effective if eGFR<45mls/min
Potassium supplmentation/potassium sparing diuretics- risk of hyperkalaemia
Lithium- renally excreted with a narrow therapeutic index

Question 14

Which drugs should be avoided in hepatic impairment?

Answer 14

Any drugs that precipitate hepatic encephalopathy
Sedatives
Diuretics- can cause hypokalaemia
Drugs that cause constipation