Pharmacokinetic basis of nifedipine-digoxin interaction: a commentary

Elevation of plasma digoxin levels following concurrent administration of nifedipine have previously been reported. The mechanism for this interaction has not been fully explained, but may include a reduction in volume of distribution of digoxin and/or reduction in the renal or non-renal clearance of digoxin by nifedipine. The end result is probably an elevation of plasma concentrations of free (pharmacologically active) digoxin, which may lead to manifestation of side effects of digoxin. This communication highlights the possible pharmacokinetic basis of the reported digoxin-nifedipine interaction.