Ursodeoxycholic acid (Ursodiol)

Ursodeoxycholic acid is an endogenous, hydrophilic bile acid used as a medication. It displaces more aggressive, fat-loving bile acids from the bile acid pool, improves bile flow and thereby protects the liver cell. In humans it naturally makes up only a few percent of the pool; under therapy its share rises considerably.

The documented indication is primary biliary cholangitis. There it measurably improves laboratory values and histology. It is also used to dissolve cholesterol gallstones.

This information is for research and educational purposes only. No medical advice.

The mechanism acts on bile flow, not on hepatocyte metabolism. That is the decisive sentence for its use with oral compounds. Ursodeoxycholic acid can favourably influence cholestasis, meaning a backup of bile. But it cannot prevent the direct cell damage from 17-alpha-alkylated compounds, because that runs through a different route.

Anyone who thinks UDCA lets them run a longer or higher oral cycle has misunderstood the mechanism. The protection it offers addresses one particular kind of liver load, not all of them.

For the approved indication the picture is clear. The controlled trial in NEJM (1991) showed markedly less treatment failure in 146 patients with primary biliary cholangitis, along with significantly better bilirubin and alkaline phosphatase. The Hepatology analysis (2008) showed that patients with a biochemical response in the first year had 90 percent transplant-free ten-year survival, versus 51 percent in non-responders.

The Cochrane review (2012) puts that in perspective: across 16 trials with 1,447 patients, no significant effect on all-cause mortality or transplantation was found. What improved were laboratory values and histology, not the hard endpoints.

The most important finding for caution comes from a different disease. In the Lindor trial (Hepatology 2009) in primary sclerosing cholangitis, high-dose ursodeoxycholic acid improved liver values and still worsened the hard endpoints, with a 2.3-fold increased risk. The trial was terminated. Better laboratory values under UDCA are therefore not proof of organ protection. That is the most important sentence on this page.

• Diarrhoea: the most common report, usually mild and dose-dependent.
• Nausea and abdominal pain: occasional, mostly at the start.
• Otherwise well tolerated: tolerability is the uncontested plus point of this substance.
• What it cannot do: prevent the direct cell damage from 17-alpha-alkylated compounds.

Store dry, at room temperature and protected from light. Keep out of reach of children.