Geriatrics: Drugs and Polypharmacy Flashcards
Polypharmacy
- Many drugs
- Even one unnecessary medication can place an elderly person at risk of an avoidable toxic reaction
What medication-related problems occur in older patients?
- Falls
- Cognitive loss/delirium
- Dehydration
- Incontinence
- Depression
What can be the end-result of medication related problems in older people?
- Loss of functional capacity
- Poor quality of life
- Nursing home placement
What adverse drug reactions can mimic the ageing process?
- Unsteadiness
- Dizziness
- Confusion
- Nervousness
- Fatigue
- Insomnia
- Drowsiness
- Falls
- Depression
- Incontinence
What is the prescribing cascade?
- Drug 1
- ADE interpreted as new medical condition so drug 2 is given
- ADE interpreted as new medical condition so drug 3 is administered and so on
How can medical conditions present differently in the young and old? Use hyperthyroidism as an example.
Young
- Tremor
- Anxiety
- Weight loss
- Diarrhoea
Elderly patient
- Depression
- Cognitive impairment
- Muscle weakness
- AF
- Heart failure
- Angina
What problems are there with over prescribing for hypertension in the elderly?
- Little evidence for tight control
- Can lead to low BP, instability and falls
- Increase in mortality
What healthcare provider factors contribute to polypharmacy?
- No medication reviews
- Presumes that patients expects meds
- Insufficient clinical investigation
- Evidence-based drug prescribing
- Provides unclear or incomplete instructions about how to take meds
- No effort to simplify med regimes
- Automatic refills
- Promotion of medications
- Lack of knowledge of geriatric pharmacology
How is absorption affected with age?
- Physiological changes occur that effect the rate but generally not the extent of absorption from the GI tract
- May lead to a delay in onset of action
How can saliva production affect GTN absorption?
A reduction in saliva production may result in a reduction in the rate of absorption of bucally administered drugs such as GTN
How is drug distribution affected by age?
Body composition changes
- Reduced muscle mass and increased adipose tissue. Fat soluble drugs: increase distribution, half-life and duration of action
- Reduced body water. Water soluble drugs: decrease distribution, increase serum levels
Protein binding changes
-Decreased albumin: decrease binding, increase serum levels of acidic drugs
Increased permeability across the blood-brain barrier
How is metabolism affected in the elderly?
Hepatic metabolism
- Decreased liver mass
- Decreased liver blood flow
What are the consequences of the changes in hepatic metabolism?
Toxicity due to reduced metabolism/excretion
Reduced first pass metabolism
- Increase in bioavailability with some drugs such as propranolol
- Can cause decrease in bioavailability of pro-drugs such as enalapril
How is excretion affected by age?
- Renal function decreases with age
- Reduces clearance and increases half-life of many drugs leading to toxicity
How is pharmacodynamics affected by age?
Increased sensitivity to particular medicines due to:
- Change in receptor binding
- Decrease in receptor number
- Altered translation of a receptor initiated cellular response into a biochemical reaction
Give examples of pharmacodynamics affected with age.
- Diazepam and increased sedation
- Warfarin and increased anti-coagulation
What drugs are most commonly implicated in ADR admissions?
- NSIADs
- Diuretics
- Warfarin
- ACEI
- Antidepressants
- B blockers
- Opiates
- Digoxin
- Prednisolone
- Clopidogrel
What are the principles for prescribing in older people?
- Where possible, be clear about the diagnosis to avoid prescribing a drug tp manage an adverse effect
- Consider whether drug therapy is the best therapeutic action
- Lower doses (or reduced frequency of administration) are generally needed
- Review drug
How can we improve patient compliance?
- Make regimes as simple as possible
- Consider possible compliance issues and address them
- Are they able to tolerate the medicine?
Why do benefits described in trial not always apply to the elderly population?
- Clinical trials are often performed in a younger population which may mean that benefits do not translate to an older age group
- However, they should not be denied on the basis of age
What prescribing tools and guides are there?
Beer’s criteria
- List of ‘inappropriate’ drugs for older people
- Updated occasionally but many weaknesses
STOPP-START criteria
- Advice on medical optimisation
- A lot to remember, so mostly research tool
NHS Scotland Polypharmacy Guidancce
What can using the STOPP-START criteria result in?
Reduction of ADRs and length of stay
Why do we de-prescribe drugs?
To reduce, substitute or discontinue a drug because:
- Adverse drug reaction
- Drug-drug interaction
- Drug-disease interaction
- Better alternative
- Not effective
- Not indicated
- Not evidence-based
- Minimise polypharmacy
What is pro-active deprescribing?
Systematic review of medication withdrawal trials in people aged >65
