Cardiac glycosides Flashcards

1
Q

digoxin pharmacokinetics

A

large Vd so in myocardium
long half life
renal elimination
low protein binding

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2
Q

antibiotic effects on digoxin

A

digoxin is metabolized by gut microflora so absorption can be altered by antibiotics
increased in potential toxicity

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3
Q

cardiac effects of dig

A
increased inotropy 
increased automaticity 
decreased rate of conduction 
shortened repolarization intervals
QT shortened 
scooping of the ST segment
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4
Q

dig effects on autonomic nervous system

A
parasym = increased release of acetylcholine 
sym = increased efferent sympathetic discharge
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5
Q

digoxin toxic dose

A

1mg in a child
3mg in an adult
>10mg in healthy subject = cardiac arrest
>3mg in child = cardiac arrest

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6
Q

digoxin toxic levels

A

> 2ng/mL

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7
Q

drug interactions

A

amiodarone (inhibits tubular secretion)
antibiotics
quinidine
verapamil

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8
Q

risk factors for toxicity

A
drug interactons
renal failure
MI
electrolyte imbalance
elderly
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9
Q

symptoms and signs of acute overdose

A
vomit
hyperkalemia
sinus bradycardia
sinoatrial arrest
second or third degree av block 
ventricular tachycardia/fibrillation 
intracellular myocardial hypercalcemia
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10
Q

symptoms and signs of chronic toxicity

A
visual disturbance - dychromatopsia
weakness
sinus bradycardia
afib
ventricular arrhythmia 
junctional tachycardia
paroxymal atrial tachycardia 
hypokalemia and hypomagnesemia from the use of diuretics
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11
Q

supportive measures for dig

A

protect airways, assist ventilation
treat hyperkalemia - insulin and glucose
bradycardia or heart block - atropine
treat ventricular tachyarrhythmias - lidocaine

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12
Q

management of intoxicated patient

A

gastric emptying
activated charcoal
MDAC
digoxin specific antibody fragments

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13
Q

monitoring of digoxin levels

A

monitor before giving antibodies bc thats what makes you decide you need to use them
dont monitor levels bc they will be increased due to presence of complexes redistributes drug from heart into plasma

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14
Q

when do you use digoxin specific antibody fragments

A

toxicity related to digoxin, digitoxin, natural cardiac glycosides

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15
Q

how does digifab work

A

bind to intravascular free digoxin

affinity for digifab greater than the affinity for the atpase

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16
Q

admin of digifab

A

infusion over 15min to 2hr

17
Q

time response for digifab

A

onset 19min

complete response 88min

18
Q

dose of digibind

A
vial = .5mg of digoxin 
# of vials = dig serum conc x wt /100
# of vials = amount ingested/.5
19
Q

empiric dosing acute ingestion

A

adult : 10-20 vial

child: 10-20 vial

20
Q

empiric dosing chronic ingestion

A

adult: 3-6 vial
child: 1-2 vial

21
Q

use digoxin specific antibody fragments for

A

life threatening cardiac glycosides toxicity
porgressive bradydysrhythmias
severe ventricular dyshrhythmia
potassium >5.5
acute ingestion >10mg adult, >4mg child
serum levels >10ng/mL
rapid progression of clinical signs and symptoms and rising potassium levels

22
Q

metabolic acidosis in cardioglycosides?

A

no

23
Q

labs to ask for

A
electrolytes
bicarb
creatinine
glucose
BUN
CPK
LDH
serum digoxin