Digoxin Flashcards
What is digoxin?
a cardiac glycoside used to support CO in late stage CHF
What are the symptoms of Stage I CHF?
none
What is the clinical presentation of Stage I CHF?
low ejection fraction (less than 50%)
What is the preferred treatment for Stage I CHF?
ACEI or ARB, BB
What are the symptoms of Stage II CHF?
moderate exertion
What is the clinical presentation of Stage II CHF?
dyspnea on exertion, edema
What is the preferred treatment for Stage II CHF?
diuretic, ACEI or ARB, BB
What are the symptoms of Stage III CHF?
minimal exertion
What is the clinical presentation of Stage III CHF?
dyspnea, orthopnea, PND, edema
What is the preferred treatment for Stage III CHF?
Digoxin, diuretic, ACEI or ARB, BB, spirolactone
What are the symptoms of Stage IV CHF?
at rest
What is the clinical presentation of Stage IV CHF?
refractory edema
What is the preferred treatment for Stage IV CHF?
Above plus combo diuretics, IV vasodilators, transplant/assistance devices
How is digoxin an inotrope?
because it increases the intracellular availability of calcium, thus increasing the force of contraction
Where does digoxin bind in a cell?
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
Interpose such as digoxin acting alone really only function to increase what?
SV, and thus CO, BUT congestive symptoms still exist
What is the effect of digoxin when added to a diuretic or vasodilator?
shift down of the frank-sterling curve and relieve congestive symptoms
How is digoxin given?
two preparations;Lanoxin- tabletsLanoxicaps- capsules
How well is digoxin absorbed?
55-60% PO (tablets) and 100% capsule absorption
How is digoxin excreted?
unchanged in urine (reduce in renal disease)
What are some of the side effects of digoxin?
-atrial/vent arryhthmias-visual changes (blurring, yellow-green halo)-headache,fatigue, drowsiness-seizures
How can digoxin ‘toxicity’ be neutralized?
digibind, an Ab to digoxin
What does quinidine do to digoxin levels?
increases by decreases elimination or by increasing Gi absorption (Amiodarone has the same effect)
What does verapamil do to digoxin levels?
can cause slowing of HR and increase digoxin toxicity
T or F. Digoxin has a VERY small therapeutic window
T. Levels vary greatly from people to people for therapeutic response
What patients benefit most from digoxin?
those with an ejection fraction less than 25% or with cardiac enlargement- late stage failure patients (class III or IV)
