Peritoneal Dialysis and Hemodialysis of Tritiated Digoxin

Abstract

The behavior of digoxin during dialysis was studied by determining blood levels and dialysate concentrations of tritiated digoxin during peritoneal dialysis and hemodialysis. The peritoneal clearance rate of digoxin was found to be 8 ml per min and the dialysance in the twin-coil artificial kidney 10 ml per min. Less than 3% of the dose of digoxin administered before dialysis was begun could be recovered by either means of dialysis. The amount of digoxin removed by dialysis is small enough to be ignored in choosing digoxin dosage in patients being dialyzed. To learn whether interaction with protein or other components of plasma modify the movement of digoxin across a dialyzing membrane, the dialysis of digoxin from saline solution was compared with the dialysis of digoxin incubated with serum. No difference in the transfer of digoxin from the 2 solutions was found, suggesting that protein binding is not a factor in limiting the dialysis of digoxin. Whole blood was incubated with digoxin and was then dialyzed in a twin-coil artificial kidney. During this in vitro hemodialysis 30% of the drug was recovered in the dialysate after 75 min. Comparison of this value with the small amoung of digoxin recovered from the patients during hemodialysis, suggests that low plasma levels and relatively inaccessable tissue stores are the major factors in limiting removal of digoxin by dialysis.