Chenodiol is well absorbed from the small intestine and taken up by the liver where it is converted to its taurine and glycine conjugates and secreted in bile. At steady-state, an amount of chenodiol near the daily dose escapes to the colon and is converted by bacterial action to lithocholic acid. About 80% of the lithocholate is excreted in the feces; the remainder is absorbed and converted in the liver to its poorly absorbed sulfolithocholyl conjugates. During chenodiol therapy there is only a minor increase in biliary lithocholate, while fecal bile acids are increased three- to fourfold.
In multiple clinical trials of chenodiol therapy for dissolution of gallstones, serum aminotransferase elevations occurred in up to 30% of patients. The elevations generally arose within 2 months of starting therapy and were typically mild, transient and not accompanied by symptoms or jaundice. Liver biopsies done during chenodiol therapy generally showed mild, nonspecific changes. Clinically apparent liver injury with jaundice was not reported. The liver enzyme elevations were generally dose related and usually did not recur on restarting chenodiol at lower doses. While the serum enzyme abnormalities that occurred on chenodiol therapy generated considerable concern, they appeared to be relatively benign. Since the approval of chenodiol and its more widespread use, at least four instances of liver injury with jaundice have been reported to the sponsor, but the clinical features and outcomes of these cases have not been published. Nevertheless, the product label for chenodiol includes a boxed warning about hepatotoxicity although it does not provide advice on the frequency or how to respond to abnormalities. Thus, the reliability of reports of clinically apparent liver injury with chenodiol therapy remains unclear. Once ursodiol was found to be equally as effective as chenodiol, even at lower doses, and was rarely associated with serum enzyme elevations, it rapidly replaced chenodiol as medical therapy for gallstones.
