SCRIPT: prescribing in older people

Question 1

Problems prescribing in the elderly.

a) Pharmacokinetics
b) Pharamacodynamics
c) Adherence
d) Adverse events

Answer 1

a) - Reduced total body water leads to increased concentration and toxicity of water-soluble drugs (eg. paracetamol, digoxin, alcohol, gentamicin, lithium, thiazides)
- Increased total body fat leads to prolonged effects of lipid-soluble drugs (eg. diazepam)
- Kidneys: reducing GFR with age leads to accumulation of water-soluble drugs; lower dose or increased interval between dosing required
- Liver: reduced CYP450 activity and reduced liver perfusion leads to reduced first-pass metabolism and increased concentrations of certain drugs (eg. morphine, nifedipine)

b) - Increased frailty leads to increased sensitivity/ susceptibility to the effects of certain drugs
- Reduced baroceptor response leads to increased risk of postural hypotension
-

c) Poor adherence in the elderly due to:
- Cognitive impairment
- Forgetting which drugs to take when
- Polypharmacy
- Side effects
- Poor dexterity
- Unable to collect prescriptions

d) Increased adverse events in the elderly due to:
- Polypharmacy - increased drug-drug and drug-disease interactions
- Multimorbidity
- Increased susceptibility and drug accumulation

Question 2

Digoxin.

a) Pharmacokinetics and how it applies to the elderly
b) Therapeutic range
c) Usual dose for AF and heart failure in younger adults and the elderly
d) STOPP criteria for digoxin

Answer 2

a) Eliminated via the kidneys
- the elderly/ those with reduced renal function will require a lower dose

b) 0.5–2 ng/m
- sample taken 6 hours post-dose
- should also take U+Es
- should also review other meds to check for any interactions or other drugs to START/STOPP

c) - AF: 125 - 250 micrograms (reduced in the elderly: 62.5 - 125 micrograms)
- Heart failure: 62.5 - 125 micrograms (reduce in the elderly)

d) - Dose > 125 micrograms if GFR < 30
- In HFPEF (HF with normal systolic function)*

*Note: useful for patients with AF + systolic HF

Question 3

Falls in older people.

a) Intrinsic risk factors
b) Extrinsic risk factors - drugs

Answer 3

a) - Comorbidities, eg. diabetes, PD, osteoporosis
- Poor mobility
- Cognitive impairment
- Poor vision

b) - Antihypertensives
- Diuretics
- Sedatives - hypnotics, benzos, opioids
- Beta-blockers
- Nitrates

Question 4

Drugs affecting cognition in the elderly

Answer 4

• Anticholinergics
• Antihistamines (particularly if sedating, eg. chlorphenamine)
• Beta-blockers
• Hypnotics
• Opioid analgesics
• Tricyclic antidepressants
• Hypoglycaemics - through hypoglycaemia
• Diuretics - through electrolyte imbalances
• Alcohol - intoxication, chronic effects (Wernicke’s encephalopathy) or withdrawal

Question 5

Managing delirium.

a) Non-pharm
b) Drug management
c) Cautions/ contraindications to these drugs

Answer 5

a) - Well-lit environment, continuity, orientation, etc.
- Management of underlying cause

b) - 1st line: low-dose haloperidol (0.5 mg - 1 mg initially, then may titrate up to max 5 - 10 mg)
- 2nd line: low-dose lorazepam* (0.5 - 2 mg)

*Risk of respiratory depression - consider patient risk factors. Also, lorazepam preferred to diazepam as not subject to the same ‘hangover effect’

c) - Haloperidol: Parkinson’s, prolonged QT (do ECG), Lewy Body dementia
- Lorazepam: respiratory depression, pulmonary insufficiency, CNS depression, reduced GCS or compromised airway

Question 6

Antimuscarinics

a) Common adverse effects
b) Can exacerbate which condition
c) Drugs with antimuscarinic effects

Answer 6

a) Memory loss
Urinary retention
Constipation
Dry eye
Dry mouth 

b) Exacerbation of glaucoma

c) - Oxybutynin
- TCAs

Question 7

NSAIDs

a) common adverse effects
b) contraindications
c) cautions

Answer 7

a) - Peptic ulcers and GI bleeding
- Nephrotoxicity
- Fluid and salt retention

b) - Active GI bleed or ulceration
- Previous NSAID-related GI bleed or ulceration
- Severe heart failure

c) - Asthma
- Crohn’s/UC
- Renal disease

Question 8

STOPP drugs: examples

a) CNS drugs - eg. amitryptilline, antipsychotics
b) CV drugs
c) Antiplatelets/AC - aspirin, warfarin
d) Gastrointestinal drugs - eg. metoclopramide

Answer 8

a) Tricyclic antidepressants (e.g. amitriptyline) prescribed to a patient with narrow angle glaucoma

b) - Digoxin prescribed long-term at a dose of greater than 125 micrograms daily to a patient with an eGFR < 30 ml/minute/1.73m2.
- Verapamil prescribed to a patient with NYHA Class III or IV heart failure

c) - Warfarin prescribed for > 6 months in a patient with first deep vein thrombosis and no continuing provoking factors
- Aspirin at long-term dose > 160 mg per day, or in patient with previous PUD without PPI adjunct

d) - Metoclopramide prescribed to a patient with Parkinsonism.

Question 9

START drugs: examples

a) CNS
b) CV
c) MSK
d) Vaccines

Answer 9

a) - L-Dopa or dopamine agonist in PD with functional impairment

b) - Statin therapy in patients with a documented history of coronary, cerebral or peripheral vascular disease should be considered, unless the patient is for end-of-life care or aged > 85 years
- Beta-blocker in patients with ischaemic heart disease

c) - Bisphosphonates in patients taking long-term systemic corticosteroids

d) - Pneumococcal vaccination at least once
- Annual flu vaccine

Question 10

Drugs to avoid in Parkinson’s

Answer 10

• Antipsychotics (other than quetiapine and clozapine)
• Dopamine-antagonist* antiemetics (metoclopramide, prochlorperazine)

*Note: domperidone is a dopamine antagonist but does NOT cross the blood-brain barrier so is safe in PD

Question 11

Patient falls out of bed in the morning. She takes citalopram 20 mg at night and zopiclone 7.5 mg at night.
a) What could you change to reduce risk of falls in this patient?

Answer 11

a) - Change citalopram to morning dose*
- Then zopiclone may be reduced or stopped
- Reduces risk of hypnosis and falls

*SSRIs taken at night can interfere with sleep. If taken in the morning, the patient will have less problems with insomnia and may not require zopiclone