Ursodeoxycholic acid treatment in humans: effects on plasma and biliary lipid metabolism with special reference to very low density lipoprotein triglyceride and bile acid kinetics.

Ursodeoxycholic acid reduces biliary saturation with cholesterol and may induce dissolution of cholesterol gallstones in man. In order to characterize the effects of this potentially useful bile acid on plasma lipid metabolism, we determined lipoprotein levels and very low density lipoprotein (VLDL) triglyceride kinetics in six hypertriglyceridaemic and three normolipidaemic subjects before and after 4-6 weeks of ursodeoxycholic acid treatment at a daily dose of 15 mg kg-1 body weight. The plasma levels of low density lipoprotein (LDL), high density lipoprotein (HDL) and total cholesterol were not significantly affected by therapy. Nor were the plasma level and apparent formation of VLDL triglycerides changed. In five subjects, the effects of a low dose (7.5 mg kg-1 body weight day-1 for 4-6 weeks) of ursodeoxycholic acid on biliary lipid composition and kinetics of cholic acid and chenodeoxycholic acid were determined. The relative concentration of cholesterol in bile was reduced to the same level as during treatment with a high dose of ursodeoxycholic acid. The synthesis rates of bile acids were not suppressed with ursodeoxycholic acid. It is concluded that, unlike chenodeoxycholic acid, ursodeoxycholic acid does not suppress endogenous bile acid production. The efficiency at lower doses, and the lack of effects on plasma lipid metabolism, may make ursodeoxycholic acid a more attractive alternative for clinical attempts of gallstone dissolution.