digoxin Flashcards
when are digoxin specific antibody fragments indicated
reversal of life-threatening overdosage.
serious cases of digoxin toxicity should be discussed with
national poisons information service
serious manifestations need urgent specialist referral
MOA
cardiac glycoside that increases the force of myocardial contraction and reduces conductivity within the atrioventricular (AV) node.
half the dose of digoxin if taken with the following 3 drugs
amiodarone
dronedarone
quinine
when switching from IV to oral, may need to increase dose by … to maintain same plasma-digoxin conc
20-33%
the following 3 electrolytes have risk of digitalis toxicity
hypercalcaemia
hypokalaemia
hypomagnesaemia
the following event has risk of digitalis toxicity
hypoxia
interaction with amino/theophylline
they are predicted to increase risk digoxin toxicity
caution
interaction with amiodarone
it moderately increases exposure to digoxin. halve digoxin dose and monitor
increased risk of bradycardia
these vitamin drugs interact with digoxin
vitamin D preps - e.g. calcitriol, alfacalcidiol, colecalciferol
they increase risk of toxicity! monitor!
remember - hypercalcaemia predisposes toxicity
this class of drugs commonly used as immunotherapy interacts
CCs increase risk of digoxin toxicity
caution
how to treat known or strongly suspected life threatening digoxin toxicity associated with ventricular arrhythmias or bradyarrhytmias
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
discuss its use in AF
controls ventricular response in persistent and permanent AF and atrial flutter
For management of atrial fibrillation the maintenance dose of digoxin can usually be determined by….
ventricular rate at rest, which should not usually be allowed to fall persistently below 60 beats per minute.
ventricular rate at rest should not usually be allowed to fall persistently below
60bpm
is a loading dose required in pt with HF
no
a satisfactory plasma-digoxin concentration can be achieved over a period of about a week.
…. function is the most important determinant of digoxin dosage
renal
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
nausea
The plasma concentration alone cannot indicate toxicity reliably, but the likelihood of toxicity increases progressively through the range
1.5-3 micrograms/litre
why should it be used with care in elderly
susceptible to digalitis toxicity
Hypokalaemia predisposes the patient to digitalis toxicity; it is managed by ….
giving a potassium-sparing diuretic or, if necessary, potassium supplementation.
what to do if toxicity occurs but no serious manifestations
withdraw digoxin
correct any electrolyte disturbances
unwanted effects depend on (2)
concentration of digoxin in the plasma
sensitivity of the conducting system or of the myocardium, which is often increased in heart disease
why are CCs, B2 agonists, theophylline, loop and thiazides etc predicted to increase risk of toxicity?
hypokalaemia
