Geriatrics Introduction Flashcards
What is the definition of “senior” or “older adult”?
conventionally age 65 in Canada
-age when many Canadians begin to receive social services
-former age of mandatory retirement
some debate among researchers
-with increased longevity, 65y is relatively young
What is a good age to start re-evaluating for meds that can cause problems?
65
True or false: old = sick
false
aging is a very heterogenous process
Why are protocols and guidelines less useful in geriatric care compared to younger patients?
because of the increasing diversity with age
-care must be individualized
What are some factors affecting health in older age?
genetics
socioeconomic status
education
social engagement and support
lifestyle: exercise/diet/smoking/alcohol
What is the definition of life expectancy?
To what proportion of the maximum age a person may live
-changes throughout life
-important when considering potential benefits of meds
What is the definition of health span?
Number of years that are spent free from functional limitations, pain, and morbidity
-goal of most geriatric models —> prolong the health span
What is functional capacity an indicator of?
Ability to carry out everyday tasks
Differentiate ADLs and IADLs.
ADLs: things you need to do to get up and going for the day
-toileting, walking, dressing, eating, bathing
-changes in ADLs need higher levels of care
IADLs: supportive tasks to maintain independence
-shopping, food preparation, medication management, financial management, house keeping
-functional impairments often show up in the IADLs before ADLs
What is functional reserve?
body systems generally have capabilities beyond what is needed for everyday activities
How does the functional reserve of an older adult compare to younger adults?
older adults have decreased functional reserve
-demands will exceed reserves
-increased risk of decline when faced with illness or injury
What is the definition of functional decline?
reduction in ability to perform ADLs and IADLs due to decreased physical and/or cognitive function
Is age the only factor in functional decline and health resource utilization?
age is a factor but not the only one
-older seniors (75+) did not always report higher healthcare use than younger seniors
-higher healthcare utilization was reported among those with more chronic medical conditions regardless of age
Which population has seen the most PK studies done?
healthy adults < 80 yrs
-limited data in oldest-old, frail
What are some GI system changes seen with age?
decreased gastric acid secretion
slower gastric emptying
delayed intestinal transit
decreased blood flow
Generally speaking, what is the impact of age on absorption of drugs?
decrease rate of absorption (first-dose, prn’s)
no change in extent of absorption
What is the caveat to the “no change in extent of absorption” with age?
decreased gastric acid secretion may decrease the extent of absorption of some meds
-iron supps
-ketoconazole/itraconazole
-calcium carbonate
What are some strategies to combat decreased acid secretion in the old for meds that require acidity?
iron supps on empty stomach
use citrate form of calcium
What is the impact of aged skin on percutaneous absorption?
aged skin tends to be drier and lower lipid content
decreased rate of percutaneous absorption of lipophilic meds, overall extent stays the same
-fentanyl, estradiol, testosterone
What are the typical changes in body composition with aging?
25-30% increase in body fat
25-30% decrease in muscle mass/body water
What are some medications with altered distribution in older adults?
highly lipophilic (accumulation = longer t1/2)
-diazepam
-amiodarone
highly hydrophilic (increased effect)
-lithium
-aminoglycosides
What is the impact of decreased albumin levels in older adults?
decreased albumin levels in frail/malnourished older adults results in decreased protein binding of highly protein bound drugs
-warfarin
-phenytoin
over time, increased metabolism/elimination compensate for this increased free fraction
start low, go slow
What is the typical change seen with the liver in older adults?
liver size and blood flow decrease significantly with age
-20-40% decrease in liver mass
-35% decrease in hepatic blood flow
mainly concerned about 1st pass effect
What kind of drugs will have increased bioavailability in older adults?
drugs with high 1st pass effect
-morphine
-metoprolol, propranolol, labetalol
-verapamil
-amitriptyline
-levodopa
Which phase of metabolism sees changes with aging?
reduction in phase I metabolism (CYP 450-mediated) with aging
no change in phase II metabolism (conjugation) with aging
What is the consequence of the reduction in phase I metabolism with aging?
longer half-lives - decreased dose requirements or increase dosing interval
What are the impacts of age on elimination?
decreased renal size, blood flow, GFR, and tubular secretion
-10% decline in GFR per decade after age 30
Is serum creatinine reliable on its own to estimate renal function?
no
-muscle mass tends to decline with age, so SCr may be falsely low
-does not account for the effect of age on kidney function
What are the available equations to estimate kidney function?
CKD-epi
MDRD
Cockfroft-Gault
What is the use of CKD-EPI?
what the SHA labs use to generate eGFR
some drugs have dosage adjustments recommended based on eGFR
What is the use of MDRD?
used more so for the staging of kidney disease
Describe some important points about the Cockroft-Gault equation.
incorporates SCr, age, gender, and weight to estimate CrCl
the equation drug-dosing recommendations are generally based on
underpredicts renal function for those weighing less than IBW
overpredicts renal function for those weighing more than IBW
What is the result of pharmacodynamic changes with age?
changes in medication response
-due to changes in receptor sensitivity or altered homeostatic mechanisms
What are the pharmacodynamic changes seen with the CV system with aging?
decreased BP-lowering response to BB
decreased arterial compliance and decreased baroreceptor reflex
increased stiffness of large blood vessels –> ISH
increased susceptibility to QT prolongation
What are the pharmacodynamic changes seen with the CNS with aging?
increased permeability of BBB
increased susceptibility to CNS AEs (benzos, antichols, dopaminergic meds)
decreased dopaminergic neurons in substantia nigra - increased susceptibility to EPS of DA blocking meds
What are the pharmacodynamic changes seen with fluid and electrolytes with aging?
decreased thirst response
decreased GFR
decreased response to ADH
decreased response to aldosterone
more susceptible to:
-hyperkalemia
-hyponatremia
-dehydration
-SIADH
What is the pharmacodynamic change seen with hematopoietic reserve with aging?
decreased hematopoietic reserve
-increased risk of hematological toxicity associated with chemotherapeutic drugs
What is the pharmacodynamic change seen with antiepileptic drugs with aging?
increased response at lower serum concentrations
-also increased susceptibility to AE’s
What is the pharmacodynamic change seen with immunosenescence with aging?
reduced ability to fight infections
reduced immune response following vaccinations
increased susceptibility to malignancy
What is the pharmacodynamic change seen with the gastric mucosa with aging?
decreased regenerative capacity of gastric mucosa
-increased risk of GI bleeds
What occurs to the therapeutic window with aging?
it narrows
-drugs are less forgiving
