Years on digoxin without trouble — why toxic now amiodarone has started?
Amiodarone pushes the digoxin level up, and slows the heart as well. It happens gradually and lasts for weeks.
Select any card for the reasoning, what to watch for and an exam tip.
The puzzle
An 82-year-old has taken digoxin for atrial fibrillation for years without a problem. The cardiology team adds amiodarone. Two weeks later he feels sick, has gone off his food, his vision seems odd, and his pulse is slow.
The answer, step by step
Who is most at risk
- Older people: the BNF advises lower digoxin doses in the elderly.
- Poor kidney function: the digoxin dose follows renal function.
- Low potassium, for example from a loop or thiazide diuretic.
- Anyone starting amiodarone, dronedarone or quinine alongside digoxin.
What to do
Key takeaway
Amiodarone raises digoxin exposure and adds its own slowing of the heart. Halve the digoxin dose when amiodarone starts, then watch for toxicity for weeks, because amiodarone lingers.