Effect of chronic administration of ursodeoxycholic acid on the ileal absorption of endogenous bile acids in man

The effect of long‐term administration of ursodeoxycholic acid on the ileal absorption of endogenous bile acids was determined using the tauro 23 ( 75 Se) selena‐25 homotaurocholic acid test in a controlled double‐blind study involving healthy subjects (n = 15). Subjects received placebo or 13 to 15 mg/kg/day ursodeoxycholic acid for 5 wk. In the placebo group (n = 7) there was no change in the composition of serum bile acids or in the mean percentage of retention of tauro 23( 75 Se) selena‐25 homotaurocholic acid (36.1% ± 6.0% vs. 38.7% ± 6.7%). In contrast, in the ursodeoxycholic acid group, serum ursodeoxycholic acid conjugates increased and the percentage of retention of tauro 23 ( 75 Se) selena‐25 homotaurocholic acid fell from 45.8% ± 6.8% to 20.5% ± 5.7% (p < 0.01). We conclude that ursodeoxycholic acid administration reduces ileal absorption of endogenous bile acids. These findings provide a rational explanation for the changes in the composition of the bile acid pool during ursodeoxycholic acid therapy and could have important therapeutic implications. (HEPATOLOGY 1990;12:1206–1208).