The hallmark paper evaluating Chenodeoxycholic Acid for gallstone dissolution therapy was Danzinger et al.. Previous studies have shown that CDCA decreased the saturation of cholesterol in bile but few prior studies had examined CDCA’s role in the dissolution of gallstones. In this caseseries by Danzinger et al., we choose 7 patients for test, seven female patients with asymptomatic radiolucent calculi underwent cholecystograms to evaluate the presence and size of gallstones. Each patient in the case series was given CDCA with a range in dosages from 0.75 to 4.5 g per day. In addition, each patient underwent cholecystokinin stimulated bile collection both prior to CDCA exposure and after administration of CDCA to evaluate any changes in bile acid composition.
After using Chenodeoxycholic Acid: four of the seven subjects within the caseseries had a decrease in the size of their gallstones. Through analysis of bile acid composition there was a notable increase in the bile salt concentration compared to cholesterol in the excreted bile salt pool. The change in composition was believed to account for the dissolution and prevention of gallstones in four of the subjects studied. 
We evaluate both Chenodeoxycholic Acid and UDCA for gallstone dissolution therapy. Chenodeoxycholic acid is part of the natural composition of bile salts. It's composes up to one third of the normal bile salt pool. Unlike CDCA, UDCA does not increase the levels of lithocholic acid,therefore, it does not cause similar side effects as CDCA. UDCA is a naturally occurring secondary bile acid that normally composes about 5 % of the circulating bile salt pool. UDCA administration alters the chemical composition of the bile salt pool to where UDCA composes 30–50 % of the entire pool, as opposed to only 5 %.