Introduction Flashcards
What is defined as senior? What is this age conventionally used?
Conventionally age 65 in Canada
- Age when many Canadians begin to receive social services
- Former age of mandatory retirement
Organization for Economic Cooperation and Development (OECD) also uses this definition
Is there a debate between researchers on the age for defining “senior” or “older adult”?
With increased longevity, 65y is still relatively young
Encompasses a lot of heterogeneity – 65 y vs 100+y
Define the aging process?
Aging is a very heterogeneous process
heterogeneity varies more as we age
What is the relationship and implication of aging and diversity?
Because of this ↑ diversity with age, protocols and guidelines are less useful in geriatric care than for younger ages
Care, including drug therapy, must be individualized
What are some other factors that affect health in older ages?
Genetics
Socioeconomic status
Education
Social engagement and support
Lifestyle: Exercise, diet, smoking and alcohol use
Define “Life Expectancy” Is it the same throughout life?
To what proportion of the maximum age a person may live
Life expectancy changes throughout the course of life
Define health span
Number of years that are spent free from functional limitations, morbidity, and pain
What is the major goal of geriatric models of care?
Goal of most geriatric models of care -> prolong the health span
Define functional capacity. What are the categories?
Indicator of ability to carry out everyday tasks
1) Activities of Daily Living (ADLs)
2) Instrumental Activities of Daily Living (IADLs)
Define ADL’s
A term used to collectively describe fundamental skills required to independently care for oneself
Things to do to get up and get up in the morning essentially
Define IADLs
Things you do every day to take care of yourself and your home
Supportive taks to. achieve independence butnot required
What are some examples of ADL’s
Dressing, toileting, eating, bathing, walking
What are some examples of instrumental activities of daily livings?
Instrumental Activities of Daily Living (IADLs)
Shopping, housekeeping, food preparation, medication management, financial management
Define the Clinical Frailty Scale
1-3 –> Not considered frail
4-5 –> Mildly frail (some evidence but still mostly able to mange independently)
Define frailty
Accumulation of functional impairments
Define functional reserve
Body systems generally have capabilities beyond what is needed for everyday activities (functional reserve)
When does impairment in function occur in geriatrics?
Impairment in function = demands exceed functional capacity
Describe the functional reserve compared to younger adults? Example?
Older adults have ↓ functional reserve compared to younger adults
↑ risk of decline when faced with illness or injury
E.g. older adult with dementia is more likely to experience post-operative delirium
Define functional decline
Reduction in ability to perform ADLs and IADLs due to decreased physical and/or cognitive function
What is age a factor for? Is it the only one? Explain.
Age is a factor in functional decline and health resource utilization, but not the only factor
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
Describe the basics of the pharmacokinetics
ADME
Heterogenous
Most PK studies in relatively healthy adults < 80 years
–> Limited data in oldest-old, frail
What PK changes occur in the Gastrointestinal system in geriatrics? What type of drug dosing is effected?
↓ gastric acid secretion
Slower gastric emptying
Delayed intestinal transit
↓ blood flow
Describe some exceptions for oral absorption pharmacokinetic changes in geriatrics? Examples? Management?
↓ gastric acid secretion may decrease the extent of absorption of some medications:
Iron supplements
Ketoconazole/intraconazole (anti-fungals)
Calcium carbonate
Suggestions to combat:
Empty stomach with iron supplements
Use citrate form of calcium
Describe the percutaneous absorption changes in geriatric patients. Examples?
Aged skin tends to be drier, lower lipid content
↓ rate of percutaneous absorption of lipophyllic medications
Fentanyl
Testosterone
Estradiol
Overall extent generally remains the same
Describe the distribution pharmacokinetic changes that occur in geriatrics
Changes in body composition with aging:
25-30% ↑ body fat
25-30% ↓ muscle mass/body water
Gradual progression over time
¼ of body mass will change from muscle to fat
What are some medications with altered distribution in older adults? Clinical Effects?
Highly lipophilic: increased distribution, increase dose (diazepam, amiodarone) - More in the fat
Highly hydrophilic: decreased distribution, decrease dose (lithium, aminoglycosides) - More in blood
Describe the pharmacokinetic changes in distrubution reagrading protein binding in geriatrics. Examples and management?
↓ albumin levels in frail/malnourished older adults
↓ protein-binding of highly-protein-bound medications:
Phenytoin
Warfarin
Over time, increased metabolism/elimination compensate for this increased free fraction
Start low, go slow
Describe the metabolism changes in PK in geriatrics? (Liver changes)
Liver size and blood flow decrease significantly with age
20-40% ↓ liver mass
~35% ↓ hepatic blood flow
What is a major change that occurs in metabolism and its effect on medications?
Major change here is first pass effect
Meds with significant first pass effect –> less first pass effect, increased F, increased effect
Describe the first-pass PK changes in metabolism in geriatrics? Examples? Management?
Describe the changes in phases of metabolism. Examples?
No change in Phase II metabolism (conjugation) with aging
Medication examples:
Acetaminophen
Lorazepam, oxazepam, temazepam
Zaleplon
Valproic acid
Describe the PK changes in elimination in geriatrics?
↓renal size, blood flow, glomerular filtration rate, and tubular secretion with aging
~10% ↓ GFR per decade after age 30
Describe the key points in kidney function in geriatrics
Serum creatinine alone not reliable
–> Muscle mass tends to ↓ with age, so SCr may be falsely low
–> Does not account for the effect of age on kidney function
What equations can be used to estimate kidney function?
Several equations available to estimate kidney function
CKD-epi
MDRD
Cockcroft-Gault
Describe the CKD-epi equation
What the Sask Health Authority labs currently use to generate the quoted eGFR
Some drugs have dosage adjustments recommended based on eGFR
MDRD Equation
Used more for the staging of kidney disease
Describe the Cockgroft - Gault Equation
Estimates CrCl
The equation drug-dosing recommendations are generally based on
Underpredicts renal function for those weighing less than their ideal body weight (IBW)
Overpredicts renal function for those weighing more than their IBW
If overweight/obese – use IBW to calculate CrCl
What causes some pharamcodynamic changes that occur in geriatrics? What does this lead to?
Changes in medication response associated with aging
Due to changes in receptor sensitivity, or altered homeostatic mechanisms
- Causes a narrowing of the “therapeutic window”
Describe some pharmacodynamic changes in the cardiovascular system in geriatrics?
↓ blood pressure-lowering response to beta-blockers
↓ arterial compliance and ↓ baroreceptor reflex
Predispose to orthostatic hypotension (fall risk in adults)
↑ stiffness of large blood vessels -> isolated systolic hypertension
↑susceptibility to QT prolongation (older women are a high risk group)
Describe the pharmacodynamic changes in the CNS in geriatrics?
↑ permeability of blood-brain-barrier with age
↑ susceptibility to CNS adverse effects of medications
Anticholinergics
Benzodiazepines
Dopaminergic medications
↓dopaminergic neurons in substantia nigra - ↑ susceptibility to extrapyramidal side effects of dopamine-blocking medications (FGA’s, Metoclopramide)
Describe the pharmacodynamic changes in fluid and electrolyte homeostasis?
↓ thirst response
↓ glomerular filtration rate
↓ response to antidiuretic hormone
↓ response to aldosterone
Fluid and electrolyte homeostasis: Geriatric patient is more susceptible to:
Dehydration
Hyponatremia
SIADH (Syndrome of inappropriate secretion of antidiuretic hormone)
Hyperkalemia
Describe the hematolgical pharamcodynamic changes
↓ hematopoietic reserve (cell producing bone marrow)
↑ risk of hematological toxicities associated with chemotherapeutic drugs
Anti-epileptic use in geriatrics: Pharmacodynamic changes?
↑ response to antiepileptic drugs at a lower serum concentration
Also ↑ susceptibility to adverse effects
Describe immunosenescene
Immunosenescence refers to aging-related changes to the immune system
What are some pharmacodynamic immune system changes in geriatrics?
Reduced ability to fight infections
Reduced immune response following vaccination
↑ susceptibility to malignancy
↓ regenerative capacity of gastric mucosa
↑ risk for GI bleeds
Describe an overall concept of the pharmacodynamic changes in geriatric patients
As frailty increases, difference between therapeutic effect and toxicity (adverse effects) becomes more narrow
