A single dose of ursodiol does not affect cyclosporine absorption in liver transplant patients

To study the possible influence of ursodiol (ursodeoxycholic acid), a hydrophilic bile acid, on cyclosporine (CsA) bioavailability. Seven adult liver transplant recipients participated in a randomised cross-over pharmacokinetic study comparing ursodiol (600 mg) with placebo in single doses. Blood concentrations of CsA were measured by HPLC. There was no significant effect of ursodiol on CsA absorption: AUC was 5011 vs 5486 ng.h.ml-1, Cmax was 832 vs 871 ng.ml-1 and tmax was 2 vs 2 h, after ursodiol and placebo, respectively. Although a significant period effect was observed, we conclude that a single dose of ursodiol has little effect on CsA absorption in liver transplant patients and that an interaction in the intestinal lumen between these two drugs is unlikely.