Check renal function and electrolyte concentrations before starting digoxin.
For intravenous infusion, continuous cardiac monitoring is recommended. It may not be necessary when IV injection is used to temporarily replace oral dosing in a patient stabilised on digoxin. Check local guidelines.
The onset of effect is approximately 5 to 10 minutes, with a maximum effect being achieved after 2 hours.
Take drug levels at least 6 hours after the dose is given.
For oral treatment without loading dose, steady state is reached after about 7 days if renal function is normal (half-life is 36 hours); this may be prolonged in renal impairment.
The therapeutic range for those with atrial tachyarrhythmias is 0.5 to 2 microgram/L (0.6 to 2.6 nmol/L) as toxicity is more common at digoxin concentrations >2 microgram/L. However, toxic effects can occur at lower concentrations, particularly in the elderly or in those with electrolyte disturbance, hypoxia or hypothyroidism. GI symptoms (e.g. nausea, anorexia) may precede cardiac symptoms (e.g. arrhythmias).
Heart failure: Consider maintaining lower concentrations of 0.5 to 0.8 microgram/L (0.6 to 1 nmol/L) in patients with heart failure who are in sinus rhythm.
Therapeutic drug monitoring for digoxin should be performed using an assay free from interference with digoxin-like immunoreactive factors, spironolactone, canrenoate, digoxin metabolites and steroids.
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