Negligible interference by spironolactone and prednisone in digoxin radioimmunoassay

Spironolactone and prednisone reportedly cause measurable values for apparent digoxin, even when none is present. Effects of these medications were evaluated with 125I-labeled digoxin kits from five different manufacturers. Values obtained for apparent digoxin were either negligible or not sufficiently great to be clinically significant, regardless of kit methodology or manufacturer.