Geriatrics Flashcards by Amanda D

In the absence of specific information, it is generally prudent to do what when administering drugs to aged patients?

“Start low and go slow”

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Aging has been described as a progress I’ve loss of…

Physiologic processes necessary to maintain homeostasis

Death being the ultimate failure of these mechanisms

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In the elderly passive gastric absorption is

Not markedly altered

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Drugs that inhibit intestinal motility have greater effect than

Age

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Due to erratic absorption and a tendency to develop sterile infiltrates, IM and SQ injections are generally recommended or not in the elder patients?

Not!

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Total Body water is decreased by what % in elderly?

10-15%

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Due to decreased thirst, elder patient may be

Dehydrated

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A decrease in TBW, in combination w/changes in the distribution of CO, results in a

Decreased central compartment volume

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Initial plasma concentrations following rapid IV admin may be increased b/c of the decreased size of the central compartment, yet the steady state distribution vol is?…. and why?

May be larger d/t increased body fat

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Body fat increases and muscle mass decreases in the elderly by what%?

How does this impact lipophillic drugs?

20-40%

So lipophillic drugs will have a large vol of distribution

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Even in healthy and exercising elderly, what is lost?

Muscle mass

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Failure to adjust for weight raises concern for this?

Over medication

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Are plasma protein levels a major concern in geriatric pharmacology?

No - not been identified

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Hepatic blood flow declines how much?

Liver mass reduces?

20-53% while liver mass is reduced 11-36%

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Tell me about hepatic function of the elderly in regards to:

Endoplasmic reticulum
Hepatic extracellular space
Bile flow

Endoplasmic reticulum is diminished
Hepatic extracellular space increased
Bile flow decreased

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What phase of liver metabolism is effected in the elderly? Why?

Phase I - which is catalyzed mainly by microsomal CYP450 enzymes may be decreased.

Enzyme activity is relatively preserved.

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Are phase II reactions affected in old age?

Appears to be unaltered

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Generally, age reduces clearance of flow-limited drugs by what ___%? Similar to the decrease in hepatic BF, but there’s is no alteration for _______ drugs.

30-40%

Capacity limited

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How much does GFR decrease per yr?

1ml/yr

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What’s the overall consensus generally about renal function and aging?

In the absence of disease

Although there is a small decrease in GFR, it probably decreases less than once thought.

Aging doesn’t appear to diminish renal drug excretion significantly

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In the elderly what happens to CO?

With coexisting disease, what happens to circulation time?

CO is maintained.

With coexisting dx - circulation times appear to increase

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Due to increased circulation times and the delay of initial drug effects, what is a prudent action to reduce overdose and adverse CV impact?

Slower bonus injections

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Opioid elimination occurs mainly by

Hepatic metabolism with renal excretion of metabolites and some parent drugs

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What factors influence opioid metabolism?

Genetics
Gender
Age
Environmental Factors
Current medications
Diet
Disease

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Name three opioids with active metabolites:

Codeine, Morphine, Meperidine

The metabolites of some opioids that are active account many side effects as well as

Persistent analgesia

The primary risks of opioids with the elderly

Respiratory depression The incidence is increased with age

Respiratory depression was more problematic with _____ vs meperidine. What is seen in pts receiving fentanyl?

Morphine And no resp depression in pts receiving fentanyl

Fentanyl is a highly selective:

Mu receptor agonist

Fentanyl is metabolized by

CYP3A4 to inactive and nontoxic metabolites

Early studies suggested what regarding fentanyl? What was the conclusion?

Early - elimination 1/2 life was prolonged in the elderly as no change in vol of distribution was found. Concluded that clearance was decreased and that fentanyl last longer in the elderly

Later studies found aging had minimal influence on fentanyl pharmacokinetics with what exception?

A transient concentration increase following the start of drug infusion Attributed tod decreased rapid intercompartmental clearance

Aging effects pharmacodynamics or pharmacokinetics greater?

Pharmaco-Dynamics “DEF” “Dynamics effect fentanyl”

Elderly pts are more sensitive to fentanyl and should receive reduced doses. What should be similar to that of young pts?

The offset of drug effect (despite smaller doses)

With oral transmucosal fentanyl, what impact did aging have on the pharmacokinetics?

None. However study in healthy older pts; so add co-morbidities and that could change

Fentanyl plasma concentrations depend on the rates of release and

Penetration through the skin layers

The mean half time (time for plasma concentrations to double after patch application) in younger (24-38yrs) and elderly (64-82) where?

Young: 4.2 and elderly 11.1 hours

In the elderly, integumentary system factors increased absorption of fentanyl overa. Longer period of time. Despite this absorption delay, what is significant about the subcutaneous fat in elderly?

It acts as a secondary reservoir — prolonging release even after removal of patch

Morphine is metabolized by what? It’s metabolites are?

Glucuronidation to morphine-3-glucoronide and to Morphine-6-glucuronide (M6G)

Tell me about M6G Can it pass BBB? Is it effective as an analgesic? Eliminated by?

BBB crosses extremely slowly It is an effective analgesic Eliminated by the kidney

What is seen in pts with elevated creatinine concentrations with morphine administration? Peak?

Accumulation of both morphine glucuronides Peak effect approx. 90min after a bolus dose

Meperidine is a relatively weak mu-agonist. It has approx ___% effectiveness of morphine

10%

Half life of meperidine is

~3hrs

Meperidine is metabolized in the liver to normeperidine. It’s half life is? What can it cause in high concnetrations?

15-30hours Causes agitation and seizures at high conc.

Meperidine has complex pharmacology... explain some of it

Local anesthetic activity negative inotropic effects Intrinsic anticholinergic props — may increase HR

When combined with MAOI’s, meperidine is associated with

Severe serotonergic reactions

Normeperidine likely accumulates in elderly due to reduced renal excretion with ..

Repeated doses

Aside from tax for post op shivering, meperidine is not a good drug in the elderly. It’s associated with this post op complication

Post op delirium

Why do we want to stop shivering?

Increased myocardial o2 demand

Remifentanil undergoes rapid hydrolysis by

Nonspecific tissue and plasma esterase

Due to its rapid hydrolysis, after a 4 hour infusion, context sensitive half life of remifentanil remains at

4 mins

Is remifentanil good in elderly populations?

Yes. Onset and offset are slower in elders but blood concentrations are similar to younger pts

After bolus injection; Peak drug effect of remifentanil Young vs old

90s vs 2-3 mins in elder

It’s recommended that elder subjects need about half the bolus dose of remifentanil than younger pts. How does this impact the effect of the drug?

Same drug effect

Remifentanil has an increased pharmacokinetic or pharmacodynamic impact?

Pharmacodynamic

Remi gtts need to be reduced about what of younger pts?

1/3 of younger pts

Remi infusion rates are about one-third that of younger patients because of:

Combined impact of INCREASED sensitivity and DECREASED clearance

Primarily b/c the elderly are more sensitive, opioid doses should be

Reduced by 50%

Propofol pharamacodynamics are significantly altered with aging. Loss of consciousness EC 50 values for 25, 50, and 75 yrs were?

25: 2.35 mcg mL-1 50: 1.8 75: 1.25 Nearly a 50% decrease

Age related changes were found in both induction and infusion doses of propofol. Pts older than 70 reached deeper EEG stages than younger pts. They needed more time to reach the deepest EEG stage and....

Needed more time until a lighter EEG stage was regained

In general - elderly need less propofol. Current literature suggests what % of reduction for induction bolus?

20%

Tell me the dose range for propofol that may be appropriate for elderly?

0.8-1.2 mg/kg

Propofol infusion rates to achieve a persistent level of moderate sedation are ______ in the elderly

Lower

Recent data indicates that propofol clearance is altered more by what in females than in males.

Age

This factor has not effect on BIS rate with increasing propofol concentration

Age

Goal BIS monitoring number

50 (40-60); Less than 40 = stage 4

With increasing age what is known to decrease to a greater degree than BIS - but more slowly?

Systolic blood pressure

Midazolam has been found to have significantly different _____ in elderly

Kinetic

Midazolam Clearance is reduced in the elderly by what % from that of young adults.

As much as 30%

Midazolam clearance reduction in the elderly is due to what two reasons:

1. Loss of functional hepatic tissue | 2. Decrease in hepatic perfusion

Midazolam undergoes significant metabolism, primarily to:

Hydroxymidazolam

Hydroxymidazolam is the primary metabolite of? Is it active or inactive?

Midazolam Active

Hydroxymidazolam (pharmacologically active) is excreted: May accumulate in patients with?

Renally excreted Accumulate in patients with diminished renal function

Why are elderly patients significantly more sensitive to Midazolam than younger patients?

Primarily b/c of a pharmacodynamic difference

The recommended Midazolam dose reduction from the 20 yr old to the 90 yr old?

75%

Paradoxical reactions are

When pts become agitated rather than sedated

How do you tx paradoxical reaction to midazolam ?

Flumazenil may reverse the episode

NMBD’s inhibit transmission at the NMJ and exert their effect

Postsynaptically

In the elderly, the average muscle mass decrease is

25-35%

Beyond the avg muscle loss, some elderly pts have significant muscle loss and weakness. This resulting state is defined as

Frail

Aging is associated with structural changes at the NMJ. What is one of the intriguing alterations in elderly muscle?

The presence of extrajunctional acetylcholine receptors .... have no known impact on NM function

Young vs old patient; ED95 for NMBD?

Essentially the same

With age, The pharmacokinetics of muscle relaxants are

Significantly altered

Onset of NMBD’s is dependent on a number of factors including

Muscle mass CO — that may be altered in elderly

Hepatically metabolized drugs

Vec and Roc

Vec & Roc (hepatic metabolized) manifest

Prolonged recovery

With Vec, in elderly vs younger pts; what is seen in regards to E 1/2t, clearance and recovery time?

Spontaneous recovery time was longer - E1/2 t was prolonged - plasma clearance was reduced

Are their differences b/w young and old with the pharmacokinetics of atracurium and cisatracurium?

Minor

Clearance of anticholinestearse in the elderly

May be prolonged. .... may be beneficial given clinical applications

Geriatric pts appear more susceptible to what SE associated w/the reversal of NMBlockade?

Cardiac arrhythmias

NMBD doses in elderly?

Are not altered. But the clinician must wait longer for the full effect (pump is slower)

Is the dose of anicholinesterase reversal drugs altered by aging?

The principal physiologic mechanisms involved in the uptake and distribution of volatile anesthetics are

Minute ventilation and CO

MV, CO and the blood/gas partition coefficient of the drug determine the rate of equilibration b/w

1. The alveolar partial pressure and | 2. The inspired anesthetic partial pressure

Senescence is associated with majors changes to what functions? However in healthy elderly pts, their baseline CO is maintained

both CV and pulmonary

MV is typically controlled during anesthesia. So what is the cause for the decreased volatile dose concentration in elderly?

Pharmacodynamic

In volatiles; this is a majore modifier of anesthetic action

Age

Two analyses found a MAC reduction of

6% per decade of life (after 1 yr age) Also seen in MAC-awake

Is the MAC reduction found with aging consistent in all, some, or none of the gases? Name them?

Consistent across all. Halothane, enflurane, isoflurane, sevo, des and N2O

On avg. volatile anesthetic MAC decreases what % per decade?

6.7% per decade

MAC for Nitrous decreases what % (and over what time period?)

7.7% per YEAR

MAC awake decreases with age

Proportionate to MAC

Monk et al study reported that what two factors were significant independent predictors of increased mortality:

1. Cumulative deep hypnotic time | 2. Intraoperative hypotension

Should we avoid volatiles in elderly patients?

There is no compelling evidence

Increase in body fat and decrease in muscle mass means for lipophillic drugs:

They’ll have a large vol of distribution

A decrease in total body water, in combo w/changes in the distribution of CO =

A decreased central compartment volume

Does aging diminish renal drug excretion?

Not significantly

Opioid doses in elderly should be reduced by

About 50%

Pharmacokinetic changes are important only when

Long term infusions are contemplated (opioids?)

Do you adjust the dose of Narcan with the elderly? If so, how

No alteration

The primary risk with increased incidence in the elderly of opioids is:

Respiratory depression

Sedative hypnotics should be SIGNIFICANTLY decreased in elderly. To minimize hemodynamics consequences, Induction doses should be

Infused more slowly

What’s one anesthetic that appears to have both pharmacokinetic and pharmacodynamic differences b/w young and old recipients?

Propofol

Elderly patients may be most sensitive to what drug? What kind of reactions may occur?

Midazolam -may have paradoxical reactions

Biggest take aways regarding NMBDs with the elderly?

Doses don’t need to be altered But the clinician must wait longer for full effect

MAC of volatiles in the elderly

Significantly reduced

Geriatrics Flashcards

(116 cards)