Geriatric Pharmacotherapy Flashcards
what is a “prescribing cascade?”
develops when ADE is misinterpreted as a new medical condition and new meds are Rx
what 4 components are involved in pharmacokinetics?
absorption
distribution
metabolism
excretion
how the drug moves through the body
what is pharmacodynamics
individuals response to a drug
effects of drug on its target/nontarget site
pharmacokinetics: what is the effect of age on absorption?
not significantly altered
factor in time to peak plasma concentration
age related change: epidermis thins and decr’d subq body fat
topical absorption increases
pharmacokinetics: what is the effect of age on distribution?
lower body water –> higher serum levels (ie. digoxin)
higher fat stores –> higher Vd –> prolonged half-life (Diazepam)
what is the MC site of drug metabolism? and the effect of age?
liver
metabolic clearance may be reduced
pharmacokinetics: what is the effect of age on metabolism?
MOST affected w/age
elderly have decr’d phase I metabolism
CYP3A4
pharmacokinetics: what is the effect of age on excretion?
Aging and common geriatric disorders can impair kidney function
Reduced elimination –> drug accumulation and toxicity
pharmacokinetics: CHF and excretion
impairment of clearance
incr’d plasma concentrations of drugs
Effect of aging on kidneys
lower GFR, even w/out kidney dz
What are some predictors of ADE’s?
6 or more concurrent chronic dz’s, 9 or more meds, 12 or more doses/day, prior ADE, low BMI, age 85 or older, est. eGFR <50 (stage 3 = 30-50)
what tool can help provide guidelines for potentially inappropriate meds use in older adults?
BEERS CRITERIA
- avoid
- avoid d/t interactions
- use caution
effective dosing and the elderly
“start low and go slow”
ie. Hydrochlorothiazide - cut pill in half for starting dose
renal and hepatic fx, pt’s age, comorbid conditions, etc.
