Geriatric pharmacology Flashcards
what are four methods to prevent the prescribing cascade?
- wait to confirm suspected diagnosis
- start low and titrate up slowly
- avoid starting multiple medications
- reach therapeutic dose before switching or adding
what are three tools for medication decisions in older adults?
Beers Criteria
STOPP
START
what is STOPP used for?
to assess use of drug with specific patient with specific conditions
what is START used for?
to identify potential underuse of beneficial medications
what are the changes in body composition during the aging process?
decrease total body water
decrease lean body mass
increase body fat
what are the CV changes during the aging process?
decrease myocardial sensitivity to beta adrenergic stimulation
decrease baroreceptor activity
decrease CO
increase TPR
what are the liver changes during the aging process?
decrease hepatic size
decrease hepatic blood flow
what are the pulmonary changes during the aging process?
decrease respiratory muscle strength decrease chest wall compliance decrease total alveolar surface area decrease vital capacity decrease maximal breathing capacity
what are the renal changes during the aging process?
decrease GFR decrease renal blood flow decrease filtration fraction decrease tubular secretion function decrease renal mass
what are the skeletal changes during the aging process?
loss of skeletal bone mass
which variable of pharmacokinetics is least affected by aging?
absorption
which component of metabolism is decreased in the elderly?
first pass
in elderly patients with reduced first pass metabolism, should a higher or lower dose be used for a drug that is inactivated by first pass?
lower
in elderly patients with reduced first pass metabolism, should a higher or lower dose be used for a drug that requires activation by first pass?
higher
equation: volume of distribution
Vd = amount of drug in body / plasma drug concentration
what does a very large Vd indicate?
majority of drug distributes to the extravascular compartment
what does a small Vd indicate?
drug is retained primarily in the vasculature
gentamicin, a highly water soluble drug, will have what kind of Vd in the elderly? why?
decreased
less body water
would a highly lipid soluble drug have an increased or decreased half life in an elderly patient when compared to a younger patient? why?
no change in half life
decreased Vd of a highly water soluble drug tends to be balanced by a reduction in clearance
drugs bound to muscle have what kind of Vd in the elderly?
decreased
definition: clearance
rate of elimination of a drug from the body in relation to drug concentration
equation: clearance
CL = Q x E
in capacity limited clearance, what it the rate limiting step?
liver enzyme function
what is the rate limiting step in flow rate limited drugs?
how fast it can get to the liver cells (flow rate)
