Biliary excretion studies with digoxin in man.

In 4 patients with a T-tube the biliary excretion of digoxin was measured for 48 hours. One patient a single intravenous bolus of 0.6 mg digoxin, while the other 3 patients were on maintenance therapy with 0.4 mg digoxin/day. From the single dose a total of 8.8% and 9.2% were excreted with the bile within 24 and 36 hours respectively. During steady-state the daily excreted amount varied between 2 and 10% of the dose in the 3 patients tested. In 2 normal volunteers the effect of the intraluminal binding agent cholestyramine on the pharmacokinetics of digoxin was investigated. The cross-over experiment did not exhibit any differences in the plasma level time profiles. These results indicate that minor amounts of digoxin are excreted with the bile which could contribute only to an insignificant enterohepatic cycling.