Digoxin

Question 1

What is digoxin?

Answer 1

a cardiac glycoside used to support CO in late stage CHF

Question 2

What are the symptoms of Stage I CHF?

Answer 2

none

Question 3

What is the clinical presentation of Stage I CHF?

Answer 3

low ejection fraction (less than 50%)

Question 4

What is the preferred treatment for Stage I CHF?

Answer 4

ACEI or ARB, BB

Question 5

What are the symptoms of Stage II CHF?

Answer 5

moderate exertion

Question 6

What is the clinical presentation of Stage II CHF?

Answer 6

dyspnea on exertion, edema

Question 7

What is the preferred treatment for Stage II CHF?

Answer 7

diuretic, ACEI or ARB, BB

Question 8

What are the symptoms of Stage III CHF?

Answer 8

minimal exertion

Question 9

What is the clinical presentation of Stage III CHF?

Answer 9

dyspnea, orthopnea, PND, edema

Question 10

What is the preferred treatment for Stage III CHF?

Answer 10

Digoxin, diuretic, ACEI or ARB, BB, spirolactone

Question 11

What are the symptoms of Stage IV CHF?

Answer 11

at rest

Question 12

What is the clinical presentation of Stage IV CHF?

Answer 12

refractory edema

Question 13

What is the preferred treatment for Stage IV CHF?

Answer 13

Above plus combo diuretics, IV vasodilators, transplant/assistance devices

Question 14

How is digoxin an inotrope?

Answer 14

because it increases the intracellular availability of calcium, thus increasing the force of contraction

Question 15

Where does digoxin bind in a cell?

Answer 15

the Na/K pump on the myocyte surface that pumps 3Na+ out for every 2K+ in using ATP. This pump is BLOCKED by digoxin, leading o a greater intracellular level of sodium. The increase in sodium then drives the increase of calcium in the cell via Na/Ca2+ exchange pumps

Question 16

Interpose such as digoxin acting alone really only function to increase what?

Answer 16

SV, and thus CO, BUT congestive symptoms still exist

Question 17

What is the effect of digoxin when added to a diuretic or vasodilator?

Answer 17

shift down of the frank-sterling curve and relieve congestive symptoms

Question 18

How is digoxin given?

Answer 18

two preparations;
Lanoxin- tablets
Lanoxicaps- capsules

Question 19

How well is digoxin absorbed?

Answer 19

55-60% PO (tablets) and 100% capsule absorption

Question 20

How is digoxin excreted?

Answer 20

unchanged in urine (reduce in renal disease)

Question 21

What are some of the side effects of digoxin?

Answer 21

• atrial/vent arryhthmias
• visual changes (blurring, yellow-green halo)
• headache,fatigue, drowsiness
• seizures

Question 22

How can digoxin ‘toxicity’ be neutralized?

Answer 22

digibind, an Ab to digoxin

Question 23

What does quinidine do to digoxin levels?

Answer 23

increases by decreases elimination or by increasing Gi absorption (Amiodarone has the same effect)

Question 24

What does verapamil do to digoxin levels?

Answer 24

can cause slowing of HR and increase digoxin toxicity

Question 25

T or F. Digoxin has a VERY small therapeutic window

Answer 25

T. Levels vary greatly from people to people for therapeutic response

Question 26

What patients benefit most from digoxin?

Answer 26

those with an ejection fraction less than 25% or with cardiac enlargement- late stage failure patients (class III or IV)