geriatrics: drugs and polypharmacy Flashcards
what is polypharmacy?
taking 5 or more medications, but starting to mean even 1 drug inappropriately prescribed (basically taking many drugs at once)
what are complications of polypharmacy?
adverse drug reactions
→ falls, cognitive loss, delirium, dehydration, incontinence, depression, loss of functional capacity, poor QoL
describe the relationship between ADRs and polypharmacy?
common iatrogenic drug reactions
anticholinergics: confusion, dry mouth, constipation, blurred vision, urinary retention and orthostatic hypotension
tricyclics: confusion, unsteady gait
benzodiazepines: CNS toxicity
digoxin: toxicity
narcotics: confusion
healthcare provider factors that contribute to polypharmacy
- no med review on regular basis
- presumes that patient wants meds
- prescribes without sufficiently investigating clinical case
- drug to drug interactions
- ordering automatic refills
what is pharmacokinetics?
what the body does to the drug
what is pharmacodynamics?
what the drug does to the body
describe changes to pharmacokinetics in older age
absorption
distribution
metabolism
excretion
what are changes to absorption in old age?
rate of absorption is changed but not the extent from GI tract
causing delayed onset of action
what are changes to distribution in old age?
body composition changes
- reduced muscle mass
- increased adipose tissue: increased distribution for fat soluble drugs
- reduced body water – decreased distribution for water soluble drugs
protein binding changes
- decreased albumin: increased serum levels of acidic drugs
increased permeability across BBB
what are changes to metabolism in older age?
hepatic metabolism: decreased liver mass and blood flow
→ toxicity
→ reduced first pass metabolism
what are changes to excretion in older age?
renal function decreases
→ reduced clearance
→ increased half-life
→ toxicity
what are pharmacodynamic changes in old age?
increased sensitivity to particular medications due to
change in receptor binding, number and translation
principles of prescribing in older people?
low does (or reduced frequency of administration)
keep regiments as simple as possible
where can drug information be found?
BNF
prescribing tools:
- Beers criteria: list of inappropriate drugs for older people
- START-STOPP criteria: advice on medical optimisation
- NHS Scotland polypharmacy guidance
