Enteroenteric circulation is the secretion back into the intestines of substances previously taken up from it. It occurs when there is a negative relative concentration of substance in the intestines, making it passively diffuse from the mesenteric circulation into the intestinal lumen and is trapped.[1]
Examples of toxins that exhibit enteroenteric circulation include theophylline, phenobarbital, and phenytoin.[1] Administration of activated charcoal inhibits the enteroenteric circulation of such substances, and is therefore useful in overdose or intoxication.[2]