Rifaximin pharmacology and clinical implications.

Rifaximin is a semisynthetic, rifamycin-based non-systemic antibiotic, with a low gastrointestinal absorption and a good antibacterial activity. The antibacterial action covers Gram-positive and Gram-negative organisms, both aerobes and anaerobes. Its antimicrobial action is based on its property to bind to the beta-subunit of bacterial DNA-dependent RNA polymerase inhibiting, thereby, the bacterial RNA synthesis. Rifaximin contributes to restore gut microflora imbalance, becoming an important therapeutic agent in several organic and functional gastrointestinal diseases such as hepatic encephalopathy, small intestine bacterial overgrowth, inflammatory bowel disease and colonic diverticular disease. This antibiotic has the advantage of low microbial resistance and few systemic adverse events and is safe in all patient populations, including young children.