Ursodeoxycholic acid (UDCA), also known as ursodiol, is a secondary

bile acid Bile acids are steroid acids found predominantly in the bile of mammals and other vertebrates. Diverse bile acids are synthesized in the liver in peroxisomes. Bile acids are conjugated with taurine or glycine residues to give anions called bile ...

, produced in humans and most other species from metabolism by intestinal bacteria. It is synthesized in the liver in some species, and was first identified in bile of bears of genus '' Ursus'', from which its name derived. In purified form, it has been used to treat or prevent several diseases of the

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

or bile ducts. It is available as a

generic medication A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active ch ...

Medical uses

UDCA has been used as medical therapy in

gallstone A gallstone is a stone formed within the gallbladder from precipitated bile components. The term cholelithiasis may refer to the presence of gallstones or to any disease caused by gallstones, and choledocholithiasis refers to the presence of ...

disease (cholelithiasis) and for

biliary sludge A bile duct is any of a number of long tube-like structures that carry bile, and is present in most vertebrates. The bile duct is separated into three main parts: the fundus (superior), the body (middle), and the neck (inferior). Bile is requ ...

. UDCA helps reduce the

cholesterol Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils. Cholesterol is biosynthesis, biosynthesized by all anima ...

saturation of bile and leads to gradual dissolution of cholesterol-rich gallstones. UDCA may be given after bariatric surgery to prevent cholelithiasis, which commonly occurs due to the rapid weight loss producing biliary cholesterol oversaturation and also biliary dyskinesia secondary to hormonal changes.

Primary biliary cholangitis

UDCA is used as therapy in

primary biliary cholangitis Primary biliary cholangitis (PBC), previously known as primary biliary cirrhosis, is an autoimmune disease of the liver. It results from a slow, progressive destruction of the small bile ducts of the liver, causing bile and other toxins to buil ...

(PBC; previously known as primary biliary cirrhosis) where it can produce an improvement in biomarkers. Meta-analyses have borne out conflicting results on the mortality benefit. However analyses that exclude trials of short duration (i.e. < 2 years) have demonstrated a survival benefit and are generally considered more clinically relevant. A Cochrane systematic review in 2012 found no significant benefit in reducing mortality, the rate of liver transplantation,

pruritus An itch (also known as pruritus) is a sensation that causes a strong desire or reflex to scratch. Itches have resisted many attempts to be classified as any one type of sensory experience. Itches have many similarities to pain, and while both ...

or fatigue. Ursodiol and obeticholic acid are FDA-approved for the treatment of primary biliary cholangitis.

Primary sclerosing cholangitis

UDCA use is associated with improved serum liver tests that do not always correlate with improved liver disease status. WHO Drug Information advises against its use in primary sclerosing cholangitis in unapproved doses beyond 13–15 mg/kg/day. UDCA in a dose of 28–30 mg/kg/day increases risk of death and need for liver transplant by 2.3-fold among those with primary sclerosing cholangitis, despite decrease in liver enzymes.

Intrahepatic cholestasis of pregnancy

UDCA has been used for intrahepatic cholestasis of pregnancy. UDCA lessens itching in the mother and may reduce the number of preterm births. Effects on fetal distress and other adverse outcomes are unlikely to be great.

Cholestasis

UDCA use is not licensed in children, as its safety and effectiveness have not been established. Evidence is accumulating that ursodeoxycholic acid is ineffective, unsafe and its use is associated with significant risk of morbidity and mortality in neonatal hepatitis and neonatal cholestasis.

Other conditions

UDCA has been suggested to be an adequate treatment of bile reflux

gastritis Gastritis is the inflammation of the lining of the stomach. It may occur as a short episode or may be of a long duration. There may be no symptoms but, when symptoms are present, the most common is upper abdominal pain (see dyspepsia). Othe ...

. Ursodeoxycholic acid has been used to treat

cystic fibrosis Cystic fibrosis (CF) is a genetic disorder inherited in an autosomal recessive manner that impairs the normal clearance of Sputum, mucus from the lungs, which facilitates the colonization and infection of the lungs by bacteria, notably ''Staphy ...

; however, a 2021 study aimed at evaluating whether the incidence of severe liver disease differed between CF centers routinely prescribing or not prescribing UDCA found no reduction in portal hypertension. UDCA has been in effective in

non-alcoholic fatty liver disease An alcohol-free or non-alcoholic drink, also known as a temperance drink, is a version of an alcoholic drink made without alcohol, or with the alcohol removed or reduced to almost zero. These may take the form of a non-alcoholic mixed drink or n ...

, in liver bile duct-paucity syndromes. It has been used as adjunct therapy in conditions with biliary tract obstruction such as

biliary atresia Biliary atresia, also known as extrahepatic ductopenia and progressive obliterative cholangiopathy, is a childhood disease of the liver in which one or more bile ducts are abnormally narrow, blocked, or absent. It can be congenital or acquired. ...

; however liver transplant is often still required as definitive treatment for atresia. It is not effective in liver allograft rejection, and in

graft-versus-host disease Graft-versus-host disease (GvHD) is a syndrome, characterized by inflammation in different organs. GvHD is commonly associated with bone marrow transplants and stem cell transplants. White blood cells of the donor's immune system which rema ...

involving the liver.

Adverse effects

Diarrhea was the most frequent adverse event seen in trial of UDCA in gallstone dissolution, occurring in 2 to 9%, which is less frequent than with

chenodeoxycholic acid Chenodeoxycholic acid (CDCA; also known as chenodesoxycholic acid, chenocholic acid and 3α,7α-dihydroxy-5β-cholan-24-oic acid) is a bile acid. Salts of this carboxylic acid are called chenodeoxycholates. Chenodeoxycholic acid is one of the ...

therapy. Bacterial conversion of UDCA to chenodeoxycholic acid may be the mechanism for this side effect. Right upper quadrant abdominal pain and exacerbation of pruritus was occasionally reported in trials in patients with PBC. Additional symptoms may include bloating, weight gain, and occasionally, thinning of hair.

Mechanisms of action

Choleretic effects

Primary bile acids are produced by the

and stored in the

gall bladder In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, althoug ...

. When secreted into the intestine, primary bile acids can be metabolized into secondary bile acids by intestinal bacteria. Primary and secondary bile acids help the body digest

fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers specif ...

s. Ursodeoxycholic acid helps regulate

by reducing the rate at which the

intestine The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. T ...

absorbs cholesterol molecules while breaking up

micelle A micelle () or micella () ( or micellae, respectively) is an aggregate (or supramolecular assembly) of surfactant amphipathic lipid molecules dispersed in a liquid, forming a colloidal suspension (also known as associated colloidal system). ...

s containing cholesterol. The drug reduces cholesterol absorption and is used to dissolve (cholesterol)

s in

patient A patient is any recipient of health care services that are performed by Health professional, healthcare professionals. The patient is most often Disease, ill or Major trauma, injured and in need of therapy, treatment by a physician, nurse, op ...

s who want an alternative to

surgery Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

. There are multiple mechanisms involved in cholestatic liver diseases.

Immunomodulating effects

Ursodeoxycholic acid has also been shown experimentally to suppress

immune response An immune response is a physiological reaction which occurs within an organism in the context of inflammation for the purpose of defending against exogenous factors. These include a wide variety of different toxins, viruses, intra- and extracellula ...

such as immune cell

phagocytosis Phagocytosis () is the process by which a cell (biology), cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs ph ...

. Prolonged exposure and/or increased quantities of systemic (throughout the body, not just in the digestive system) ursodeoxycholic acid can be toxic.

Anti-inflammatory effects

Ursodeoxycholic acid has been shown to exert anti-inflammatory and protective effects in human epithelial cells of the

gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...

. It has been linked to regulation of immunoregulatory responses by regulation of

cytokine Cytokines () are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are produced by a broad range of cells, including immune cells like macrophages, B cell, B lymphocytes, T cell, T lymphocytes ...

s, antimicrobial peptides

defensin Defensins are small cysteine-rich cationic proteins across cellular life, including vertebrate and invertebrate animals, plants, and fungi. They are host defense peptides, with members displaying either direct Antimicrobial, antimicrobial activit ...

s, and take an active part in increased restitution of wound in the colon. Moreover, UDCA's effects has been shown to have exert actions outside the epithelial cells. While some bile acids are known to be colon tumor promoters (''e.g.''

deoxycholic acid Deoxycholic acid is a bile acid. Deoxycholic acid is one of the secondary bile acids, which are metabolic byproducts of intestinal bacteria. The two primary bile acids secreted by the liver are cholic acid and chenodeoxycholic acid. Bacteria m ...

),. others such as ursodeoxycholic acid are thought to be

chemopreventive Chemotherapy (often abbreviated chemo, sometimes CTX and CTx) is the type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) in a standard regimen. Chemotherapy may be given with a cu ...

, perhaps by inducing cellular differentiation and/or cellular senescence in colon epithelial cells.

Chemistry

Ursodeoxycholic acid is an

epimer In stereochemistry, an epimer is one of a pair of diastereomers. The two epimers have opposite configuration at only one stereogenic center out of at least two. All other stereogenic centers in the molecules are the same in each. Epimerization is t ...

, which has similar choleretic effects and a wider species distribution. However, CDCA is not as well-tolerated in humans and it does not show immunomodulating or chemoprotective effects. Both are 7-hydroxyl derivatives of deoxycholic acid, but UDCA has the group in the beta instead of the alpha orientation.

Biosynthesis

Among mammals, only bears (

Ursidae Bears are carnivoran mammals of the family (biology), family Ursidae (). They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats ...

; excluding

giant panda The giant panda (''Ailuropoda melanoleuca''), also known as the panda bear or simply panda, is a bear species endemic to China. It is characterised by its white animal coat, coat with black patches around the eyes, ears, legs and shoulders. ...

s) produce UDCA at useful amounts (>30%). It is produced in the bear liver, but the pathway remains unknown. Other vertebrates produce UDCA in much smaller amounts by gut bacteria. CDCA is oxidized into 7-oxo-CDCA then reduced into UDCA.

Industrial production

UDCA is most commonly produced from

cholic acid Cholic acid, also known as 3α,7α,12α-trihydroxy-5β-cholan-24-oic acid is a primary bile acid that is insoluble in water (soluble in alcohol and acetic acid), it is a white crystalline substance. Salts of cholic acid are called cholates. Cho ...

(CA) derived from bovine bile, a by-product of the beef industry. The current yield of this

semisynthesis Semisynthesis, or partial chemical synthesis, is a type of chemical synthesis that uses chemical compounds isolated from natural sources (such as microbiology, microbial cell cultures or plant material) as the starting materials to produce novel ...

is about 30%.

Society and culture

Names

The term is from the Latin noun '' ursus'' meaning bear, as bear bile contains the substance. Ursodeoxycholic acid can be chemically synthesized and is marketed under multiple trade names, including Ursetor, Udikast, Actibile, Actigall, Biliver, Deursil, Egyurso, Heptiza 300/150, Stener, Udcasid, Udiliv, Udinorm, Udoxyl, Urso, Urso Forte, Ursocol, Ursoliv, Ursofalk, Ursosan, Ursoserinox, Udimarin, and Ursonova.

History

Bear bile, a natural source of UDCA, has been used in

traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medicine, alternative medical practice drawn from traditional medicine in China. A large share of its claims are pseudoscientific, with the majority of treatments having no robust evidence ...

since the seventh century. Japanese scientists successfully synthesized UDCA chemically in 1955. The earliest reference to UDCA in

PubMed PubMed is an openly accessible, free database which includes primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. The United States National Library of Medicine (NLM) at the National Institute ...

dates to 1957 under an alternative spelling "ursodesoxycholic acid", in a small-scale clinical trial. Ursodeoxycholic acid (application filed by

Allergan Allergan plc is an American, Irish-domiciled pharmaceutical company that acquires, develops, manufactures and markets brand name drugs and medical devices in the areas of medical aesthetics, eye care, central nervous system, and gastroenterology. ...

) was approved for use in the United States in December 1987, and was designated an

orphan drug An orphan drug is a medication, pharmaceutical agent that is developed to treat certain rare medical conditions. An orphan drug would not be profitable to produce without government assistance, due to the small population of patients affected by th ...

References

{{DEFAULTSORT:Ursodeoxycholic Acid Drugs developed by AbbVie Bile acids Cholanes Drugs acting on the gastrointestinal system and metabolism Orphan drugs