Chenodeoxycholic acid (chenic acid; CDCA) is 1 of the 3 major biliary bile acids in man. When administered in pharmacological doses it causes a decrease in cholesterol saturation of bile, which in turn may lead to gradual dissolution of cholesterol gallstones. The stone dissolution rate during CDCA therapy has varied considerably from about one-third of patients overall to 80 to 90% in a highly selected group of patients. Radiolucent gallstones in a functioning gallbladder are absolute requirements. 

  Chenodeoxycholic acid is well tolerated; diarrhoea (sometimes requiring dosage reduction) is the only frequent side effect. Although hepatotoxicity has occurred in certain animal species, and slight hypertransaminasaemia has occurred in some patients, definite liver damage has not been observed in man. Chenodeoxycholic acid is considered contraindicated in pregnancy, and in those patients with the complications from gallstones which require immediate surgery. Care should be taken in patients with liver disease. The only other proven agent for dissolving gallstones is the 7 beta-epimer of Chenodeoxycholic acid, ursodeoxycholic acid (UDCA). Preliminary results show that UDCA is as effective as CDCA, but at one-half to two-thirds the dose, without causing diarrhoea. Further studies need to be done with both CDCA and UDCA to improve criteria for selection of patients most likely to respond, and to establish optimum schedules for dosage and duration of treatment.