Ursodeoxycholic acid (UDCA), also known as ursodiol, is a naturally-occurring bile acid that constitutes a minor fraction of the human bile acid pool.2, 3 UDCA has been used to treat liver disease for decades: its first use in traditional medicine dates back more than a hundred years.1, 6 UDCA was first characterized in the bile of the Chinese black bear and is formed by 7b-epimerization of chenodeoxycholic acid, which is a primary bile acid.2 Due to its hydrophilicity, UDCA is less toxic than cholic acid or chenodeoxycholic acid.2
UDCA was first approved by the FDA in 1987 for dissolution of gallstones and for primary biliary cirrhosis in 1996.2 UDCA works by replacing the hydrophobic or more toxic bile acids from the bile acid pool.2
