The Sunnybrook Gallstone Study was a randomized, double-blind, controlled trial of chenodeoxycholic acid treatment over 2 years in 160 patients with radiolucent gallstones. Sixty-four patients received 750 mg daily, 5 3 received 375 mg daily and 43 received placebo. Total dissolution of gallstones occurred in 10.9% of patients on 750 mg daily, 13.2% of those on 375 mg daily and in no patient on placebo. The drug was tolerated well. Diarrhea severe enough to cause withdrawal from the study occurred in two patients. No patient developed clinically significant hepatotoxicity. Serum cholesterol rose 10% or more above baseline after 2 years in 33% of patients treated with chenodeoxycholic acid and in 30% of those on placebo. Cholecystectomy was performed in 10.9% of patients on 750 mg daily, 17% on 375 mg daily and 13.6% on placebo. Chenodeoxycholic acid given at these doses dissolved radiolucent gallstones safely but the efficacy was limited.
Cholesterol gallstones are common and they impose considerable morbidity, significant mortality and a large economic burden on our health services. Intensive investigation of the pharmacological dissolution of cholesterol gallstones began in the early 1970's. Of the primary bile acids, chenodeoxycholic acid (CDCA), but not cholic acid, was found to reduce the cholesterol saturation of bile (1). The first report of gallstone dissolution by CDCA in patients was that of Danzinger et al. ( 2 ) . Many reports of gallstone dissolution with CDCA then followed. Some of these studies involved small numbers of patients while other studies were large but, uncontrolled. Because a controlled, double-blind clinical trial was needed, the National Cooperative Gallstone Study (NCGS) was organized in the United States with 10 centers participating. The Sunnybrook Gallstone Study (SBGS) was organized along lines similar to those of the NCGS. The aim of this single center study was to investigate the efficacy and safety of CDCA in a population of Canadian patients. Two doses of CDCA were compared, a 375 mg daily dose, described previously as effective for gallstone dissolution (Danzinger, R. G., Gastroenterology 1977; 72:1042, Abstract), and a 750 mg daily dose, representative of a higher dose regimen. The results of this study, which involved 183 subjects, are reported here.