DIGOXIN

Question 1

Class

Answer 1

Cardiac glycosides

Question 2

Digoxin - therapeutic range

Answer 2

Therapeutic Range: 0.7ng/ml -
2.0ng/ml

Question 3

How can you tell toxic effects are happening?

Answer 3

Toxic risk increases from 1.5 to 3 mcg/litre for digoxin

Question 4

Indication

Answer 4

• AF/ Atrial flutter
• Only effective at rest
• Role in HF

Question 5

How do you determine the achieved maintenance dose in
AF with digoxin?

Answer 5

• Determine by the ventricular rate at rest
• Which should NOT fall persistently under 60 BPM

Question 6

For heart failure, is a loading dose required?

Answer 6

• No, a loading dose is NOT required
• A satisfactory plasma-digoxin concentration can be achieved over a period of about a week

Question 7

Digoxin’s half-life and dosing

Answer 7

Digoxin has a long half-life and maintenance doses need to be given only once daily

Question 8

What is the most important determinant of the maintenance dose of Digoxin?

Answer 8

Renal function

Question 9

CI

Answer 9

• 2nd degree AV heart block
• WPW syndrome

Question 10

SE - toxicity

Answer 10

• Arrhythmias
• N& V
• Brady
• Blurred/ Yellow vision
• Anorexia
• Confusion, dizziness

SICK + SLOW

Question 11

What do unwanted effects depend on?

Answer 11

• Both the concentration of digoxin in the plasma and the sensitivity of the conducting system or of the myocardium, which is often increased in heart disease

Question 12

Which patient group are particularly susceptible to digitalis toxicity and therefore digoxin should be used in caution with them?

Answer 12

elderly

Question 13

What are the monitoring requirements for Digoxin?

Answer 13

1. Plasma-digoxin concentration assay
   - Blood should be taken at
   least 6 hours after the dose
2. Serum electrolytes and renal function
   - Toxicity is increased by electrolyte disturbances

Question 14

What electrolytes (when disturbed)
increase the risk of digitalis toxicity?

Answer 14

1. Hypercalcaemia
2. Hypokalaemia - give K sparing diuretic, potassium suppls
3. Hypomagnesaemia

Question 15

If digitalis toxicity is suspected, what do you do?

Answer 15

1. Digoxin should be withdrawn
2. Give atropine sulfate
3. If life-threatening overdose, give Digoxin-specific antibody fragments

Question 16

What is the dose of digoxin in AF and HF?

Answer 16

The daily dose in Heart failure is half that of AF
Max dose is 250mcg OD for AF and 125mcg for HF

Question 17

Which drugs may precipitate digitoxin toxicity when taken with digoxin?

Answer 17

1. Verapamil, diltiazem
2. Diuretics
   - Thiazide
   - Loop
   - Spironolactone
3. Amiodarone
4. Ciclosporin
5. Quinine