Geriatric Pharmacology ARS Session Flashcards
Geriatric patients make up ___ of the population and yet receive ___ of prescription drugs
13% of population taking 30% of the total prescription drugs
1 take home from this lecture
D/C the amytriptyline
What does not change much with advancing age?
Absorption - bioavailability does not change, but peak serum concentrations may be lower or delayed
Exceptions to which drugs aren’t as bioavailable in older people
Drugs with extensive first-pass effect - eg nitrates so serum concentration may be higher because less drug is extracted by a smaller liver
Factors that affect drug absorption
- Food taken with the drug (SA carbidopa/levodopa)
- Comorbid illness (diabetic gastroparesis)
- Enteral feedings (phenytoin)
- Drugs that increase gastric pH or affect GI motility may affect absorption ( PPIs and iron)
Hypertensive woman is switched from atenolol to propanolol - becomes despondent and confused. This is due to what?
Lipophilia
Effects of aging on VD
- Decreased body water –> lower VD for hydrophilic drugs
- Decreased lean body mass –> lower VD for drugs that bind to muscle
- Increased fat stores –> higher VD for lipophilic drugs and lipid soluble more likely to get into brain
- Decreased plasma protein –> higher % of drug that is unbound
Aging and metabolism
- Liver is most common site of drug metabolism
- Metabolic clearance of drug by liver may be reduced because of decreased flow, size etc
Phase I vs Phase II metabolism in aging
Phase I - convert drugs to metabolites
Phase II - pathways convert drugs to inactive metabolites that do not accumulate
Drugs metabolized by phase II is preferred/safer for older patients
Recall: The Old Liver
Which pharmacokinetic factor changes accounts for most change in drug effects with age
Elimination
Since you have to use Cockroft-Gault… what kind of rough estimate can you use to estimate aging effects on renal function?
10 ml/decade decline
With ___ age and ___ body weight, the serum creatinine becomes less reliable
advancing age, decreasing body weight
How come serum creatinine does not reflect creatinine clearance?
Decreased lean body mass means less creatinine made, and therefore less to clear
Pharmacodynamics
What the drug does to the body
Pharmacokinetics
What the body does to the drug
Why are elderly at greater risk for bleeding at any given INR?
They have additional problems that increase the risk (friable stomach, more likely to fall & suffer head trauma)
Adverse Drug Event
Any noxious, unintended and undesired effect of a drug, excluding therapeutic failures, poisoning or abuse
Most common cause of adverse drug reactions in the elderly is:
Number of medications prescribed
What percent of ambulatory older adults receive at least one potentially inappropriate drug?
20%
Sphincter that controls the bladder is under what kind of control?
Alpha 1 adrenergic
To hold it, you gotta inhibit parasympathetic
When to be cautious about medication withdrawal
- Sudden cessation of amytriptyline may cause a cholinergic rebound syndrome (agitation, borborygmi diarrhea)
- Sudden withdrawal of clonidine may cause rebound hypertension but less likely with dose less than 1 mg daily
What kinds of drugs can induce parkinsonism
Metoclopramide, valproic acid, prochlorperazine
Why is digoxin no longer a geriatric staple
Absence of LV systolic dysfunction or Afib with RVR means dig can be d/c
In aFib with RVR, slows rate at rest but not with exertion
We have better drugs.
RR, AR, or NNT?
AR reduction and NNT are the most important things when deciding whether or not to give someone a drug.
Parsimony
Prescribe as few drugs as possible
Look at definitions of ARR and RRR
RRR: (incidence control- incidence Rx)/
incidence control
ARR: (incidence control-incidence Rx)
NNT: 100/ARR
Silo thinking
“Silo thinking”: failure to account for impact of multiple chronic diseases on medication efficacy and safety
Deprescribing
Deprescribing is the process of tapering or stopping drugs, aimed at minimizing polypharmacy and improving patient outcomes
Principles of management of elderly with multiple chronic diseases
- Choose treatments that have clinical impact within life expectancy of patient and fewest adverse effects
- Choose treatments that may have benefit for more than one chronic disease
