Rifaximin is a broad-spectrum oral antibiotic, exhibiting limited systemic absorption, that is
used clinically to treat a variety of gastrointestinal disorders, including traveller’s diarrhea, hepatic
encephalopathy, irritable bowel syndrome, and the inflammatory bowel diseases. Rifaximin’s
antimicrobial properties, in the context of enteric infections, and its effects on the host’s intestinal
microbiota have been well characterized. More recently, it has been reported that rifaximin can
modulate host tissue function through the activation of distinct molecular events. Within the
gastrointestinal tract, rifaximin is a selective agonist of the pregnane X receptor (PXR), a nuclear receptor that regulates
the expression of genes related to xenobiotic metabolism and drug detoxification. The PXR can also elicit
immunomodulatory effects through its interaction with a variety of intracellular signaling cascades, including the nuclear
factor kappa B and c-jun N-terminal kinase pathways. In this review, we will summarize the clinical uses of rifaximin and
discuss its mechanism of action in relation to the modulation of the intestinal microbiota and the regulation of
gastrointestinal host cell function, with a specific focus on PXR-dependent pathways.
Keywords: Crohn’s disease, hepatic encephalopathy, infectious colitis, inflammatory bowel diseases, irritable bowel
syndrome, microbiota, pregnane X receptor, Rifaximin, ulcerative colitis.
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