Cardiac glycosides

Question 1

MOA: Inhibits Na/K+-ATPase pumps –> intracellular accumulation of sodium –> intracellular accumulation of calcium –> increased contractile force

Answer 1

Digoxin

Question 2

In AF, the mechanism of action is mainly via an indirect pathway involving increased vagal tone

Answer 2

Digoxin

Question 3

Indications:
- Reduces ventricular rate in AF or atrial flutter
- In severe heart failure, this drug may be added if treatment with an ACE-inhibitor, beta blocker, and either Spironolactone/ARB is insufficient

Answer 3

Digoxin

Question 4

Important adverse effects include bradycardia, GI upset, rash, dizziness, and visual disturbance (YELLOW VISION).

NARROW THERAPEUTIC INDEX

Answer 4

Digoxin

Question 5

Digoxin is contraindicated in second degree heat block, intermittent complete heart block, and in ventricular arrythmias

Answer 5

Contraindications for Digoxin

Question 6

Digoxin is excreted via the

Answer 6

kidneys

Question 7

Low levels of ________, __________, and _________can increase risk of digitalis toxicity

Answer 7

potassium, magnesium, and calcium

Question 8

How does digoxin toxicity cause hyperkalaemia?

Answer 8

Digoxin toxicity causes hyperkalemia, or high potassium. The sodium/potassium ATPase pump normally causes sodium to leave cells and potassium to enter cells. Blocking this mechanism results in higher serum potassium levels

Question 9

What type of drugs increase the risk of digoxin toxicity by causing hypokalemia?

Answer 9

Diuretics

Question 10

Therapeutic doses of Digoxin produce what characteristic ECG finding?

Answer 10

The “reverse tick” of ST segment depression

Question 11

Investigations/monitoring during Digoxin use

Answer 11

ECG
Electrolytes
Renal function