[Simultaneous prescription of digoxin and an anti-arrhythmia agent, is it dangerous?]

Many anti-arrhythmic drugs modify the pharmacokinetics of digoxin and increase serum levels. This possibility is considered for the majority of main anti-arrhythmics on the basis of a review of the literature. Quinidine, propafenone, flecainide, amiodarone and verapamil increase blood digoxin levels, sometimes to twice their baseline values. Suggested mechanisms involve above all a decrease in clearance of digoxin and changes in its volume of distribution. Reported accidents considered to be a direct consequence of these interactions are nevertheless rare in the literature, and the need for modifying dose and increased cardiological surveillance in the case of such a combination is essentially a question of precaution. Disopyramide, procainamide and mexiletine do not appear to have any reported effects on the pharmacokinetics of digoxin, their combined prescription never having had any effect on blood digoxin levels.