Gallstones. The present and future of medical dissolution.

Adequate concentrations of bile acids and phospholipids are necessary to keep cholesterol in solution in bile. When the amount of cholesterol exceeds the capacity of bile acids and phospholipids to keep the cholesterol in micellar solution, bile becomes supersaturated; then, under appropriate conditions, cholesterol crystals form and gallstones may develop. Current dissolution therapy is aimed at desaturating the bile, thereby shifting the equilibrium of cholesterol from a crystalline phase back toward a micellar state, thus permitting gallstones to dissolve. Chenodeoxycholic acid is the drug being most extensively tested for efficacy in dissolution; at present, it is successful in about 60 per cent of cases. The primary mechanism of action appears to be suppression of biliary secretion of cholesterol. Further experience is needed to confirm the safety of chenodeoxycholic acid, to gain more precision in patient selection, and to determine ideal dose. The role of chenodeoxycholic acid in prophylaxis and in prevention of recurrence needs further study. Other potential agents for dissolution also deserve investigation.