DISORDERS ASSOCIATED WITH AGEING

Question 1

ADME - absorption/distribution in the elderly

Answer 1

• less body water means increased plasma concentration of water-soluble drugs (lithium, antibiotics)
• less lean body mass means lower binding and increased plasma concentration of highly muscle-bound drugs (digoxin)
• less plasma protein (albumin) so less binding and increased concentration of protein-binding drugs (phenytoin, warfarin)
• metabolism is reduced (smaller liver mass, less liver blood flow, enzyme function reduced)

Question 2

ADME - excretion in the elderly

Answer 2

• shrinkage in kidney size, less blood flow = reduced renal function
• normal creatinine concentrations possible in elderly with significant renal impairment (use GFR to estimate renal function)
• dosage adjustment required in renal impairment

Question 3

ADME - pharmacodynamics in the elderly

Answer 3

• changes in receptor binding/receptor numbers
• fewer neurons/post-receptor ‘events’ - affects responsiveness of the target organ
• increased sedation with BZs
• decreased effectiveness of beta-blockers

Question 4

CNS disorders associated with ageing

Answer 4

• loss of neurons and neurotransmitters (cognitive impairment/dementia/AD)
• vascular changes to the brain affecting blood/oxygen supply (i.e. stroke)
• PD (loss of dopaminergic cells)

Question 5

consequences of anticholinergic medication in elderly

Answer 5

• elderly experience more adverse effects i.e. constipation, urinary retention, dry mouth/eyes, sedation, confusion (misdiagnosed as dementia)
• increased risk of dementia associated with long-term/regular use of anticholinergic drugs

Question 6

other factors to consider in ageing

Answer 6

• psychological impact of physical ill health - side effects
• lifestyle - loneliness? esp. if living alone/loss of partner - social isolation
• retired - may lack routine, feelings of self-worth
• lower income - affordability of food/heating

Question 7

5 key patient groups in liaison psychiatry

Answer 7

1. self-harm
2. alcohol/drug misuse
3. dementia/delirium/depression
4. known chronic/severe mental illnesses
5. medically unexplained symptoms - psychological component to illness, Munchausen syndrome

Question 8

capacity

Answer 8

the ability to make and communicate a decision

Question 9

capacity/consent in mental health

Answer 9

staff must not give medication in a disguised form unless the pt has refused and their mental health is at risk because of this

ESSENTIAL MEDICATION ONLY

Question 10

drugs to avoid in elderly

Answer 10

• block a1 adrenoceptors
• have anticholinergic side effects
• are sedative
• have a long half-life
• are potent inhibitors of hepatic (CYP) enzymes

Question 11

prescribing principles in elderly

Answer 11

1. use drugs only when necessary
2. avoid certain drug groups/side effects
3. start with low dose and increase gradually
4. avoid treating side effects with another medication - consider non-pharmacological alternatives
5. keep it simple (few drugs, once daily dosing, similar formulations)
6. review routes of administration