Flashcards in older adults Deck (44):
why is the study of pharmacology critical in older patients
because they have the highest percentage of prescriptions, there are many off-label uses, there are many interactions.
does the bioavailibility change with age
does the peak serum concentration change with age
yes. could be lowre or delayed.
what must be kept in mind when considering the serum concentration of an older person
drugs that have first pass effect. their bioavailability may increase because there is less liver and blood flow. this is contradictory to the above card.
what can the affect the absorption of drugs
divalent cations, enteral feedings, increased gastric pH, drugs that effect GI motility.
what drug is specifically affected by cation
what drug is specifically affected by enteral feedings
what are the effects of aging of distribution
decreased body water means lower VD for hydrophilic drugs.
decreased lean mass means lower VD for muscle bound
increased fat stores means higher VD for lipophilic
decreased plasma protein means a higher percentage of the drug is unbound
why would metabolic clearance by the liver be decreased
aging decreases the blood flow, size, and mass of liver,
what are the phase I paths
oxidation, hydroxylation, dealkylation, reduction.
what does the phase I do
converts drugs to metabolites with greater, lesser or the same effect as the parent compound
phase II paths
convert drugs to inactive metabolites that do not accumnulate.
what phase metabolism drugs are preferred for older patients
phase II drugs.
examples of protein bound drugs
warfarin, barbiturates, phenytoin, carbamezapine
examples of phase I drugs
long acting benzodiazepam
examples of water soluble drug
exampes of lipid soluble drugs
can gender effect the metabolism of a drug
what is the half-life
time for serum conc to decline by 50%
what is the clearance
volume of serum for which the drug is removed per unit time
where do most drugs exit the body
kidney . if there is reduced elimination there is accumulation and toxicity. aging can impair function
what are the effects of aging o n the kidneyh
decreased size, blood flow, number of functioning nephrons, renal tubular secretion. the result is lower GFR
does the serum Cr reflect the clearance in an older person
no. there is decreased lean mass, and decreased GFR so the range will stay in the normal masking changes.
how do we calculate the Cr clearance
need 24 hr collection to be accurate and cockroft and Gault equation.
what is the pharmacodynamics
time course and intensity of the pharmacological effects of a drug.
do the pharmacodynamics change with age
yes. likely by reduced clearance.
what are the most common medications that cause ADE
cardiovascular, CNS, MSK. meds that have a narrow therapeutic window.
what are the risks for ADE
6 or more concurrent chronic conditions
12 or more doses of drugs/day
9 or more meds
prior adverse reaction
low body weight or BMI
older than 85
what are ADE misinterpreted as
new medical conditions
what are the risks for drug-drug interactions
increased number of medications consumed esp high risk, multiple prescribers, multiple pharmacies, physiologic and pharmacokinetic changes
what are the most common drug-drug interactions
cardiovascular and psychotropic
what are the key facts of drug drug
absorption can up or down, drugs with similar or opposite effects can result in changes in effect, drug metabolism can be induced or inhibited. herbals!
most common adverse affects of drug drug
confusion, cognitive impairment, arterial hypotension, acute renal failure.
ACEi and diuretic risk
hypotension and hyperkalemia
ACEi and potassium risk
antiarrhythmetic and diuretic risk
electrolyte imbalance and arrhythmias
benzo and antidepressant, antipsychotic, or benzo
confusion, sedation, falls,
CCB and diuretic or nitrate
digatalis and antiarrhythmetic
bradycardia and arrhythmia
what is a drug-disease interaction
when a drug interacts with aberrant physiology of the patient
what is the interaction between obesity and lipophilic drugs
there is a greater VD.
what disease can affect hydrophilic drugs
what can dementia do to drugs
increase the sensitivity induce paradoxical reactions