Digoxin levels can be approximately doubled by
amiodarone. Some individuals may show even greater increases. Digitalis
toxicity will occur if the dosage of
digoxin is not reduced appropriately.
The interaction occurs in most patients and is clearly evident after a few days but may take 4 weeks to fully develop. Reduce the
digoxin dosage by between
one-third to one-half initially and monitor
digoxin levels. Further adjustment of the
digoxin dosage may be needed after a week or two, and possibly a month or more depending on
digoxin levels. Particular care is needed in children, who may show much larger rises in
digoxin levels.