Geriatric drugs Flashcards by tcarlso 3

What is the definition of polypharmacy?

Greater than 5 drugs/week

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What are the two leading causes of death in ages over 65?

Heart disease

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What is the “prescribing cascade”?

Prescribing a drug, which causes an adverse effect, and prescribing another b/c you interpreted the new symptom is a new problem, rather than a side effect

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What are the ways to prevent the prescribing cascade?

Avoid prescribing until confirm dx
Titrate slowly
Add one drug at a time

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In is inadequate monitoring?

A medical problem is being treated with the correct dru, but the pt is not monitored for complications, efficacy, or both

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What is it called when a medical problem that requires drug therapy is being treated with a less than optimal drug?

Inappropriate drug selection

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What is it called when a patient is taking a drug for no medically valid reason?

Inappropriate treatment

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What is Beer’s criteria?

List of medications likely to cause adverse effects in the elderly

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What are the three criteria that are used in the Beers criteria?

Drugs problematic is most older pts
Problematic for certain diseases
Drugs to be used with caution

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What are the three major physiological functions that decline with age, and are relevant to pharmacokinetics?

Glomerular filtration rate
Max breathing capacity
Cardiac index

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What happens with weight as we age?

Goes down, but fat mass goes up

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What happens to total body water with age?

Decreases

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What happens to lean body mass with age?

Decreases

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What happens to myocardial sensitivity to beta adrenergic stimulation?

Decreased

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What happens to baroreceptor sensitivity with age?

Decrease

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What happens to CO with age? TPR?

Lower CO

Increased TPR

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What happens to liver size with age? Hepatic blood flow?

both Decrease

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What happens to pulmonary function in general with age? Renal function?

Decrease

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What are the four components of pharmacokinetics?

Absorption
Distribution
Metabolism
Clearance/elimination

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What is the parameter of drug pharmacokinetics that is least affected by aging?

Absorption

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Why is first pass metabolism reduced with aging?

Reduced liver function and blood flow

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What is bioavailability?

Fraction of drug reaching the systemic circulation (IV dose = 100%)

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What is the relative dose needed for a prodrug in the elderly? Why?

Increased dose d/t lower metabolism by the liver

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What is the equation for the volume of a drug’s distribution?

Amount of drug in body (mg) / plasma [drug]

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A large Vd indicates what?

Most of the drug is in the extravascular compartment

How does a lipophilic drug distribution change in the elderly? Why?

Increase since there is a higher fat mass and lower lean muscle mass

What happens to the Vd in the elderly with water soluble drugs, or drugs that bind to muscle? Why?

Lower since elderly have lower body water and muscle content

What is the equation for half--life of a drug?

t(1/2) = ln(2) x Vd/CL

Would a highly lipid soluble drug have an increase or decrease t1/2 in an elderly patient compared to a younger patient?

Increased

What happens to the t1/2 with a decreased Vd with water soluble drugs? Why?

Decreased Vd of water soluble drugs leads to less of an increase in half life since this tends to be balanced by a reduction in clearance by the kidneys

What is the equation for the loading dose?

Vd * target [c] / bioavailability

Would the loading dose of a highly water soluble drug be larger or smaller in an elderly pt when compared to a younger one?

Lower

What happens to Vd with water soluble drugs with aging? What is the effect of this on the half life? Loading dose?

Lower Vd Lower half life Lower loading dose

What happens to Vd with lipid soluble drugs with aging? What is the effect of this on the half life? Loading dose?

Higher Vd Increased half life Higher loading dose

What is the equation for drug clearance?

CL = QxE: Q = flow rate to organ, E = extraction ratio

What is the CL(total)?

CL (liver) + CL (renal) + CL (other)

What is the extraction ratio?

Relative efficiency of an organ to eliminate drugs from the systemic circulation

What are the phase I enzymes? What do these do?

p450s | Oxidize/reduce

What are the phase II enzymes? What do these do?

Conjugation

What is the effect of aging on phase I and II enzymes?

I - decrease | II - same

What is a capacity limited drug?

A drug whose hepatic clearance rate-limiting step is liver enzyme function.

What happens to clearance of a drug in the elderly if it is primarily metabolized by phase 1 enzymes? Phase 2?

I - decrease | II - same

What is a flow rate limited drug?

A drug whose rate-limiting hepatic clearance step is flow rate

What happens to drugs that are flow rate limited in the elderly?

Reduced hepatic clearance

To keep the drug at a steady state, the maintenance rate of drug administration must equal what? What is the significance of this in the elderly?

The rate of clearance at the steady state Lower maintenance doses needed, unless phase II

How much does GFR decrease with age?

15-40%

What happens to tubular secretion in polypharmacy?

Increases the risk of drugs competing for active transporters

What is the substance that measures GFR?

Creatinine

What is GFR?

sum of all filtration rates of nephrons

What is the equation for creatinine clearance?

Cc = (Ucm x V) / Pcm

Why is it that GFR in the elderly can be normal, despite reduced renal function?

Lower muscle mass = lower creatinine

What is the reason for the Cockcroft and gault equation?

Account for creatinine differences in older people, different weights, and in different sexes

Why do lipophilic drugs have an increase in half life in elderly pts?

Increased fat and increase Vd

What happens to the volume of distribution and bioavailability of water soluble drugs in the elderly?

Decreased Vd | Increased plasma concentration

What happens to the Vd and half life for lipophilic drugs in the elderly?

Increased

What happens to the sensitivity to anesthetic agents in the elderly?

Increased

What happens to the sensitivity to beta adrenergic agents in the elderly? Why?

Decreased | Beta receptors are less responsive

What happens to the blood pressure changes in the elderly with Ca channel blockers?

Lower response

NSAIDs are primarily cleared by what organs? What is the significance of this in the elderly?

Kidney | Lowers the kidney's ability to compensate for the loss of nephrons in the elderly

What is the MOA of NSAIDs?

Cox inhibition

What are the elderly susceptible to with NSAIDs? Why?

Renal damage | Loss of the kidney's ability to compensate for the loss of nephrons in the elderly

What are the major side effects of anticholinergic agents in the elderly?

``` Hypotension Blurred vision (both lead to falls) ```

What are the meds that have high anticholinergic properties? (11)

``` Anticonvulsants Antidepressants (TCAs) Antihistamines Antipsychotics Cardio GI antispasmodics H2 antagonists Muscle relaxants Parkinson Urinary antispasmodics Vertigo ```

What happens to the rate of first pass extraction in the elderly? How does this relate to the bioavailability of the drug?

Decreases Increased bioavailability

Geriatric drugs Flashcards

(64 cards)