Ursodeoxycholic acid (UDCA), also known as ursodiol, is a compound produced from bile by the action of intestinal bacteria. Since this bile acid is not produced directly by the body, it is known as a secondary bile acid. One of the functions of bile acids is to act in the intestine to help digest fats and fat-soluble vitamins from food. Ursodeoxycholic acid has been used in pharmacology to dissolve gallstones made of cholesterol, and to treat liver disorders. It has been used for a long time in both human and veterinary medicine.
Bile is produced in the liver, stored in the gallbladder, and sent through a duct into the small intestine. The majority of bile consists of derivatives of cholesterol called bile acids. There are a number of different types of these compounds. Their diversity is increased by the action of intestinal bacteria on the body’s bile acids. Some of these acids are toxic and are generally eliminated by excretion into the stool.
Bile acids can be reabsorbed into the liver. When the liver is healthy, it can eliminate toxic acids. If it is damaged, however, the toxins can accumulate and further damage the organ. Ursodeoxycholic acid improves the flow of bile both into the gall bladder, and from the gall bladder into the intestine. The toxic bile acids are then eliminated from the body.
Due to this activity, ursodeoxycholic acid is used as a medication. It is marketed as Actigall® or URSO, among other names. This drug is one of the treatments approved by the United States Food and Drug Administration (FDA) for primary biliary cirrhosis. This is an autoimmune disease of the liver, in which the bile ducts are damaged. This causes bile to accumulate in the liver and damages the tissue over time. Ursodeoxycholic acid treats this condition because it is absorbed preferentially over more toxic acids, and thereby reduces damage to the liver.
Ursodeoxycholic acid also controls cholesterol levels by several mechanisms. It reduces the absorption of cholesterol from food being digested. This compound also reduces the amount of it made by the liver. Additionally, the acid increases the degradation of cholesterol. There are different types of cholesterol, and ursodeoxycholic acid metabolizes the form that tends to cause gallstones.
Its tendency to dissolve gallstones made of cholesterol has led to clinical usage to dissolve this type of growth, thus eliminating the need for surgery. There are some disadvantages to this approach. The drug is expensive, and often the gallstones return once drug treatment is stopped. With the advent of lapraroscopic gallbladder removal, this method is used only for people who wish to avoid surgery, or for whom such a procedure would be considered too dangerous.
There are several medications that should not be taken with this bile acid. Antacids containing aluminum will inactivate it. Cholesterol-lowering medications, estrogen, and birth control pills can all interfere with the effectiveness of this drug. One should not use this treatment when there is a gallstone obstructing the common bile duct, because it is considered somewhat risky to increase bile flow under these conditions.
Ursodeoxycholic acid is found in the bear bile used in traditional Chinese medicine. Bear gall bladders have been used for centuries as a homeopathic to treat liver disorders. Commercially, this compound is made in a laboratory, rather than being obtained from actual bear bile. There are many references, however, to bears being raised in Asia, as a source of bile to treat a wide variety of ailments.