Cardiac Glycosides aka Digoxin Flashcards
Digoxin’s MOA is super HY.
Inhibition of Na-K ATPase causes Na to stay inside cell. This increased Na+ gradient affects the Calcium Na exchanger - removing Sodium that way and leaving more Calcium stored in SER–> increasing muscle contractility.
Digoxin Clinical Use is perfect for Systolic Dysfunction.`
HF, A-fib, RVR
Adverse Rxns of Digoxin are terrible. Also has a low TI.
Cholinergic (N,V,D), Hyperkalemia, Blurry Yellow or Green Vision (because unlike most cells, rods and cones for vision depend on K+ for transmembrane potential). Increased risk of arrhythmias bc resting membrane potential is disrupted and closer to threshold.
GI with the Digi. lol
How is Digoxin excreted?
Renal.
Toxicity of Digoxin is increased in which states?
Renal Failure, Hypokalemia (Digoxin is already competing with K+…this will worsen that), Drugs which may displace Digoxin.
Digoxin binds Albumin…but so do which other Cardiac drugs which will compete?
Verapamil, Amiodarone, Quinidine all love to bind Albumin.
Treatment of Digoxin toxicity.
Give Mg++ cofactor to SLOWLY normalize K+ level. Give AntiDigi Fab fragments. If all fails, use Cardiac Pacemaker (catheter with electrical impulses)
Digoxin is excreted urinary so you cannot give to anyone with decreased renal function. What would you see on ECG with toxicity?
Inverted T wave, increased PR interval, decreased QT interval.
78 F has N/V/D with Hx of A-fib. Inverted T waves, increased PR interval. Blurry yellow tint. Which drug and its MOA?
Digoxin. Inhibits Na-K+ ATPase. Inverted T wave due to hyperkalemia even tho normally hyperkalemia presents with a peaked T wave. This is bizarre and specific to Digoxin hyperkalemia.
Think GI with the Digi and visual change and ECG.
Although digoxin can be used to manage CHF and does cause an increased ejection fraction, how does it affect Vagal tone?
Causes increased, not decreased, vagal tone. Thereby increasing contractility while decreasing HR!
How do Loop diuretics affect Afterload?
Loop diuretics cause decreased end-diastolic volume and afterload.
How does Nesiritide affect End Diastolic Volume?
decreased end-diastolic volume and increased natriuresis!
How does Nitroglycerin effect EDV?
decreased end-diastolic volume and a small decrease in afterload.
What are treatment options for digoxin toxicity?
Treatment options include normalization of electrolytes, administration of lidocaine, digoxin immune Fab, and magnesium.
