Usosan Mechanism of Action

Pharmacology: Pharmacodynamics: Ursodeoxycholic acid is a gallstone dissolving agent which acts by reducing the content of cholesterol in bile. This may be due either to a reduction in hepatic cholesterol synthesis or reduced absorption of cholesterol or both.
Pharmacokinetics: Intestinal absorption after an oral dose of ursodeoxycholic acid is high, with a first-pass clearance of about 50 to 60%. Studies show that passive diffusion occurs, whereupon the drug enters the enterohepatic circulation and is subject to an efficient hepatic extraction mechanism. The 'spillover' into the systemic blood supply is therefore minimal. Plasma levels are not clinically important but may be useful in estimating patient compliance; they reach maximum concentrations at about 60 minutes after ingestion with another peak recorded at 3 hours.
Ursodeoxycholic acid is rapidly conjugated with glycine and taurine in the liver. Microbial biotransformation of the drug and its metabolites occurs when they leave the enterohepatic circulation and is responsible for high levels of faecal lithocholic and 7-ketolithocholic acids during ursodeoxycholic acid therapy. Intestinal flora also hydrolyse conjugated drug back to the parent compound and interconvert ursodeoxycholic and chenodeoxycholic acids.