Elderly- Polypharmacy Flashcards
What does polypharmacy mean?
Many drugs
As the number of drugs a patient takes increases, what also increases?
The chance of adverse drug reactions
What are common Medication related problems/ ADRs in older people?
- Falls
- Cognitive Loss /delirium
- Dehydration
- Incontinence
- Depression
- Unsteady- dizziness and confusion
Why older people take so many drugs?
- More acute and chronic illnesses
* Prescribing cascade- drugs given to counteract the side effect of another drug
What are symptoms of ADR that can be confused with old age?
Unsteady, dizzy, confusion, falls, depression, incontinence
What is the prescribing cascade?
- Given a drug that causes an ADR
- ADR interpreted as a new condition
- Given another drug to treat the ADR
What changes as people get older?
Pharmacokinetics
How does absorption of a drug change as a person gets older?
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 does the distribution of a drug change as a person gets older?
Body composition changes
• Reduced muscle mass
• Increased adipose tissue
• Reduced body water
How do changes in distribution affect fat soluble drugs?
Increased volume of distribution
Increased half-life
Increased duration of action
How do changes in distribution affect water soluble drugs?
Decreased volume of distribution
Decreased half-life
Decreased duration of action
How does protein binding change as a person gets older?
There is a decrease in albumin
Decreased binding leads to increased serum levels acidic drugs e.g. furosemide
Increased permeability across blood brain barrier
How does metabolism change as a person gets older?
Hepatic metabolism is affected by
• Decreased liver mass
• Decreased liver blood flow
What are the consequences of decreased hepatic metabolism?
- Toxicity due to reduced metabolism/excretion
- Reduced first pass metabolism
- Increase in bioavailability with some drugs e.g. propranolol
- Decreased bioavailability of pro-drugs e.g. enalapril (pro-drugs are drugs that have to pass through the liver to be metabolised to work)
How does excretion change with increasing age?
- Renal function decreases with age
* Reduces clearance and increases half-life of many drugs leading to toxicity
Why is there increased sensitivity to particular medications?
- Changes in receptor binding,
- Decrease in receptor number,
- Altered translation of a receptor initiated cellular response into a biochemical reaction.
What are the 3 main principles of prescribing in older people?
- Review prescriptions regularly
- Try to keep regimes simple
- Consider compliance issues in older people
What is deprescribing?
To reduce, substitute or discontinue a drug
What are most adverse drug events from?
Anticholinergics and Sedatives
What effect can benzodiazepines have on elderly people?
Falls and confusion
What effect can anti-psychotics have on elderly people?
Postural hypotension, stroke, confusion, movement disorders
What is the problem with anti-depressants in elderly people?
They are less effective and more dangerous
What is the problem with opioids in the elderly?
Older people are more sensitive to effects, so lower doses needed
What effects can NSAID’s have in the elderly?
Can cause renal impairment and GI bleeding
What is the problem with digoxin in the elderly?
Increased toxicity so lower doses needed
What is the problem with anti-hypertensives in the elderly?
- May have exaggerated effects on BP and HR
- More likely to be issues with postural hypotension
- Renal adverse effects
What is the problem with anticoagulants in the elderly?
More sensitive to warfarin so greater risk from warfarin i.e. GI bleeding, falls
What adverse effects can antibiotics have on the elderly?
- Diarrhoea and c. diff infection
- Blood dyscrasias (trimethoprim, co-trimoxazole)
- Delirium (quinolones)
- Seizures
- Renal impairment (aminoglycosides)
