Enterohepatic circulation (EHC)

Enterohepatic circulation refers to the physiological process where substances such as bile acids, bilirubin, and certain drugs are secreted from the liver into the bile, transported to the small intestine, and subsequently reabsorbed back into the portal circulation for return to the liver (StatPearls, NBK547737). This recycling mechanism is essential for maintaining the bile acid pool, which is critical for the emulsification and absorption of dietary lipids and fat-soluble vitamins (Wikipedia). While it is a complex physiological pathway rather than a single molecular target, it serves as a major site for pharmacological intervention. For instance, bile acid sequestrants and ileal bile acid transporter (IBAT) inhibitors disrupt this cycle to treat hyperlipidemia and cholestatic liver diseases by promoting the fecal excretion of bile acids (PubMed, 31863399). Dysfunction in this process can lead to various clinical conditions, including gallstone formation, malabsorption syndromes, and altered drug pharmacokinetics. Understanding this circulation is vital for drug development, as it significantly influences the half-life and systemic exposure of many therapeutic agents.

Other names

Enterohepatic cyclingBiliary recyclingBile acid circulation

Pharmacological modulation typically involves the inhibition of specific transporters (e.g., ASBT/SLC10A2) or the physical sequestration of bile acids within the intestinal lumen to prevent their reuptake and promote excretion.