Digoxin

Question 1

Class

Answer 1

Cardiac stimulant

Question 2

Actions

Answer 2

Slows heart
Slows AV conduction
Prolongs AV node
refractory period
Increases force of
contraction in failing
heart

Question 3

Adverse effects

Answer 3

Dysrhythmias
Yellow vision
Nausea
Vomiting

Question 4

Clinical use

Answer 4

Atrial fibrillation

Heart failure

Question 5

Mechanism of action

Answer 5

Inhibits Na+/K+ ATPase in
plasma membrane
Increased intracellular
Na+ reduces Ca2+
extrusion thus increasing
Ca2+

Question 6

use of Digoxin now

Answer 6

used in Atrial Fibrillation, but now very much third line treatment option. Rarely used in heart failure as much better drugs available.

Question 7

use of Digoxin

Answer 7

used to treat congestive heart failure, and supraventricular arrhythmias

Question 8

Digoxin mode of action

Answer 8

inhibition of the Na-K-ATPase membrane pump, resulting in an increase in intracellular sodium. This causes in turn the sodium calcium exchanger (NCX) to extrude the sodium and pump in more calcium.

Question 9

what happens as a result of altered calcium concentration

Answer 9

is thought to promote activation of contractile proteins (e.g., actin, myosin)

Question 10

how does digoxin affect the hearts electrical activity

Answer 10

increases the slope of phase 4 depolarization, shortening the action potential duration, and decreasing the maximal diastolic potential.