RIFAXIGEM-550 Tablets RIFAXIGEM-550 contains Rifaximin, a non-systemic, broad-spectrum antibacterial agent derived from rifamycin. Rifaximin acts locally within the gastrointestinal tract by binding to the beta-subunit of bacterial DNA-dependent RNA polymerase, leading to the inhibition of bacterial RNA synthesis and subsequent inhibition of protein synthesis. Due to its minimal gastrointestinal absorption (less than 0.4%), high local drug concentrations are achieved in the intestinal lumen without significant systemic bioactivity or systemic side effects. Rifaximin exhibits bactericidal activity against a wide range of enteric Gram-positive and Gram-negative, aerobic and anaerobic pathogens. It reduces intestinal ammonia-producing flora, decreases gut mucosal permeability, and alters local inflammatory pathways. RIFAXIGEM-550 is indicated for the reduction in risk of overt hepatic encephalopathy recurrence in patients with advanced chronic liver disease, treatment of irritable bowel syndrome with diarrhea (IBS-D) in adults, treatment of traveler's diarrhea caused by noninvasive strains of Escherichia coli, and small intestinal bacterial overgrowth (SIBO).