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
