digoxin

Question 1

when are digoxin specific antibody fragments indicated

Answer 1

reversal of life-threatening overdosage.

Question 2

serious cases of digoxin toxicity should be discussed with

Answer 2

national poisons information service

serious manifestations need urgent specialist referral

Question 3

MOA

Answer 3

cardiac glycoside that increases the force of myocardial contraction and reduces conductivity within the atrioventricular (AV) node.

Question 4

half the dose of digoxin if taken with the following 3 drugs

Answer 4

amiodarone
dronedarone
quinine

Question 5

when switching from IV to oral, may need to increase dose by … to maintain same plasma-digoxin conc

Answer 5

20-33%

Question 6

the following 3 electrolytes have risk of digitalis toxicity

Answer 6

hypercalcaemia
hypokalaemia
hypomagnesaemia

Question 7

the following event has risk of digitalis toxicity

Answer 7

hypoxia

Question 8

interaction with amino/theophylline

Answer 8

they are predicted to increase risk digoxin toxicity
caution

Question 9

interaction with amiodarone

Answer 9

it moderately increases exposure to digoxin. halve digoxin dose and monitor

increased risk of bradycardia

Question 10

these vitamin drugs interact with digoxin

Answer 10

vitamin D preps - e.g. calcitriol, alfacalcidiol, colecalciferol

they increase risk of toxicity! monitor!

remember - hypercalcaemia predisposes toxicity

Question 11

this class of drugs commonly used as immunotherapy interacts

Answer 11

CCs increase risk of digoxin toxicity
caution

Question 12

how to treat known or strongly suspected life threatening digoxin toxicity associated with ventricular arrhythmias or bradyarrhytmias

Answer 12

gie atropine
if unresponsive, digoxin specific antibody fragments can be given

these can also be given when measured beyond withdrawal of digoxin and correction of any electrolyte abnormalities are considered necessary

Question 13

discuss its use in AF

Answer 13

controls ventricular response in persistent and permanent AF and atrial flutter

Question 14

For management of atrial fibrillation the maintenance dose of digoxin can usually be determined by….

Answer 14

ventricular rate at rest, which should not usually be allowed to fall persistently below 60 beats per minute.

Question 15

ventricular rate at rest should not usually be allowed to fall persistently below

Answer 15

60bpm

Question 16

is a loading dose required in pt with HF

Answer 16

no
a satisfactory plasma-digoxin concentration can be achieved over a period of about a week.

Question 17

…. function is the most important determinant of digoxin dosage

Answer 17

renal

Question 18

Digoxin has a long half-life and maintenance doses need to be given only once daily although higher doses may be divided to avoid this side effect

Answer 18

nausea

Question 19

The plasma concentration alone cannot indicate toxicity reliably, but the likelihood of toxicity increases progressively through the range

Answer 19

1.5-3 micrograms/litre

Question 20

why should it be used with care in elderly

Answer 20

susceptible to digalitis toxicity

Question 21

Hypokalaemia predisposes the patient to digitalis toxicity; it is managed by ….

Answer 21

giving a potassium-sparing diuretic or, if necessary, potassium supplementation.

Question 22

what to do if toxicity occurs but no serious manifestations

Answer 22

withdraw digoxin
correct any electrolyte disturbances

Question 23

unwanted effects depend on (2)

Answer 23

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

Question 24

why are CCs, B2 agonists, theophylline, loop and thiazides etc predicted to increase risk of toxicity?

Answer 24

hypokalaemia

Question 25

this abx class is predicted to increase the conc of digoxin. monitor digoxin conc

Answer 25

macrolides - clarith, erythromycin, azith

Question 26

these antifungals interaction

Answer 26

amphotericin B - predicted to increase the risk of Digoxin toxicity when given with Digoxin. Manufacturer advises caution.

Azoles - itracon, ketocon, posacon,
are predicted to markedly increase the concentration of Digoxin. Manufacturer advises monitor Digoxin concentration.

Question 27

St Johns wart interaction

Answer 27

St John’s wort decreases the concentration of Digoxin. Manufacturer advises avoid.

Question 28

RL-CCB interaction

Answer 28

Verapamil, diltiazem increases the concentration of Digoxin. Manufacturer advises monitor and adjust dose.

Both Digoxin and Verapamil can increase the risk of bradycardia.

Question 29

interaction with acetylcholinesterase inhibitors, BB (no class of interaction)

Answer 29

e.g. rivastigmine, donepezil, galantamine

increase risk of bradycardia

Question 30

spinorolactone, eplerenone interaction

Answer 30

Spironolactone increases the concentration of Digoxin. Manufacturer advises monitor and adjust dose.

Question 31

IV calcium interaction

Answer 31

intravenous Calcium increases the effects of Digoxin. Manufacturer advises avoid.

Question 32

quinine, chloroquinine, mefloquine interaction

Answer 32

Quinine increases the concentration of Digoxin. Manufacturer advises monitor and adjust Digoxin dose.
Mefloquine is predicted to increase the risk of bradycardia when given with Digoxin. Manufacturer makes no recommendation.

Question 33

anti arrhythmic interactions - propafenone, dronedarone,

Answer 33

Dronedarone is predicted to moderately increase the exposure to Digoxin. Manufacturer advises monitor and adjust Digoxin dose.

Question 34

routine monitoring not needed. however, when you do take plasma-digoxin conc assay when should blood be taken after dose?

Answer 34

For plasma-digoxin concentration assay, blood should be taken at least 6 hours after a dose.

Question 35

monitoring

Answer 35

Monitor serum electrolytes and renal function. Toxicity increased by electrolyte disturbances.

Question 36

common SE

Answer 36

Arrhythmias; cardiac conduction disorder; cerebral impairment; diarrhoea; dizziness; eosinophilia; nausea; skin reactions; vision disorders; vomiting

Question 37

What are some symptoms of toxicity

Answer 37

GI disturbances: nausea, vomiting, diarrhoea
Visual disturbances: blurred vision, yellow vision, halos around lights
Neurological disturbances: confusion, dizziness, fatigue
Cardiac: bradycardia, arrhythmias, heart block

Question 38

What to do if digoxin toxicity suspected

Answer 38

If toxicity is suspected, check digoxin levels and electrolytes, adjust dosage, may need to withdraw digoxin and correct any electrolyte imbalances and, in severe cases, treat with digoxin-specific antibodies (Digibind).