Ursodeoxycholic acid: a review of its pharmacological properties and therapeutic efficacy.

Ursodeoxycholic acid is the 7 beta-hydroxy epimer of chenodeoxycholic acid and is normally present in only trace amounts in the bile. Oral administration of pharmacological doses markedly decreases biliary cholesterol saturation. Complete or partial dissolution of radiolucent gallstones located in a functioning gallbladder occurred in about 40 to 55% of patients treated with ursodeoxycholic acid in controlled studies of 6 months duration. Patients showing partial gallstone dissolution at that time are likely to continue improving possibly to complete gallstone dissolution with continued therapy. The success rate with ursodeoxycholic acid may be increased top about 80% if more stringent patient selection criteria are applied to include only those with non-calcified floating cholesterol stones of less than 10 to 15 mm diameter. Those with calcified stones or stones greater than 15 mm diameter or unlikely to respond to ursodeoxycholic acid therapy. The optimal dose in published studies was about 8 to 10 mg/kg/day, which is about half to two-thirds the dose of chenodeoxycholic acid (15 mg/kg/day) achieving approximately equivalent results. Ursodeoxycholic acid appears to be remarkably well tolerated, with diarrhoea occurring in only a very small proportion of patients. While surgery is clearly the preferred treatment in many patients with symptomatic gallstones, in a carefully selected subgroup of such patients gallstone dissolution therapy with ursodeoxycholic acid offers an important and worthwhile alternative.