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drug dosing in the critically ill patients Flashcards

1
Q

what are the 4 phases of critical illness

A

rescue (fluid resuscitation, vasoactive drugs)
optimization (preserve organ & tissue function)
stabilization (clinical improvement)
de-escalation (weaning of support)

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2
Q

what are the ideal characteristics of a medication in the ICU

A

predictable bioavailability
fast onset
rapid titratability
wide therapeutic window

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3
Q

which route is most common in the ICU

A

IV (100% bioavailability)

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4
Q

which routes have high/low bioavailability?

A

IV has 100%

IM, SQ, transdermal, sublingual, enteral have lower bioavailability

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5
Q

what are some patient factors in the critically ill that will affect ABSORPTION

A

gastric pH
GI motility
regional blood flow
peripheral or gut edema

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6
Q

what things DECREASE absorption

A

perfusion abnormalities
GI motility
altered gastric pH
bowel wall edema
drug- nutrient interactions

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7
Q

what are some examples of commonly used ICU drugs that are affected by changes in ABSORPTION

A

itraconazole- needs an acidic medium
phenytoin- drug/nutrient interactions
enoxaparin- incompletely absorbed in the setting of pressors and edema

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8
Q

a drug’s distribution depends on both ___ and ___

A

the patient’s physiology (blood flow, protein, body composition)
AND
the properties of the drug (protein binding affinity, solubility, molecular weight, etc)

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9
Q

what are some contributors to changes in Vd?

A

fluid shifts, tissue perfusion, changes in plasma protein binding

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10
Q

hydrophilic drugs have a ______ Vd and are thus dependent on ______

A

smaller
tissue perfusion & blood volume
(reduced tissue perfusion will decrease the distribution of hydrophilic drug)

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11
Q

what are some factors that can INCREASE Vd

A

large volume resuscitation
capillary leak syndrome
ascites
mechanical ventilation
hypoalbuminemia

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12
Q

what are some drugs affected by hypoalbuminemia

A

albumin-bound drugs
amiodarone
ceftriaxone
midazolam
morphine
phenytoin
propofol
valproic acid
warfarin

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13
Q

what are some drugs affected by: large volume resuscitation, capillary leak, ascites, mechanical ventilation

A

hydrophilic drugs
aminoglycosides
beta lactams
daptomycin
hydromorphone
morphine
vanco

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14
Q

what would DECREASE Vd

A

decreased alpha l-acid glycoprotein

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15
Q

drugs affected by decreased alpha l-acid glycoprotein

A

medications bound to alpha l-acid glycoprotein
azithromycin
carvedilol
fentanyl
lidocaine
olanzapine
phenobarbital

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16
Q

_____ is the primary site for drug metabolim

A

LIVER

17
Q

why might hepatic drug elimination be altered during critical illness?

A

changes in blood flow & intrinsic enzyme activity
(liver is highly perfused, 30% of cardiac output, when CO decreases it will impact drug clearance)

18
Q

what are some factors that may INCREASE metabolism

A

hepatic enzyme induction
augmented hepatic blood flow

19
Q

drugs affected by increased metabolism?

A

flow dependent drugs (high extraction drugs)
propofol
midazolam
morphine
metoprolol

20
Q

what are some factors that may DECREASE metabolism

A

hepatic enzyme inhibition
decreased hepatic blood flow

21
Q

drugs affected by decreased metabolism?

A

flow-independent medications (low extraction drugs)
warfarin
diazepam
phenytoin

22
Q

______ are the primary organ responsible for drug elimination

A

kidneys

23
Q

what are some factors that can INCREASE clearance

A

augmented renal clearance
extracorporeal removal

24
Q

drugs affected by INCREASED clearance

A

renally eliminated medications
beta lactams
vancomycin
enoxaparin
gabapentin
levetiracetam

25
Q

what are some factors that can DECREASE clearance

A

AKI

26
Q

drugs affected by AKI

A

nephrotoxic meds
aminoglycosides
NSAIDs
antivirals
contrast

27
Q

creatinine lags by ___ from the onset of kidney damage

A

48 hours

(as much as 50% of kidney function is lost before detectable changes in SCr occur)

28
Q

____% of critically ill patients experience AKI

A

20-50%

29
Q

affects on drugs in CKD

A

decreased clearance
increased half life
accumulation of active metabolites (morphine)
decreased kidney drug metabolism
altered drug distribution (protein binding)

30
Q

dosing considerations for hemodialysis

A

give dose after hemodialysis
supplemental doses after hemodialysis
consider the dialyzer
dialysis times

31
Q

dosing considerations for peritoneal dialysis

A

timing of dose (random compared to hemodialysis recommendations, look up specific drug)
route of admin: IV vs peritoneal
residual urine output

32
Q

drug removal in dialysis depends on?

A

size of drug molecule
other factors like protein binding, Vd, solubility, flow rates, etc

advanced nephrology (7 decks)

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