RIFAXIGEM-400 Tablets RIFAXIGEM-400 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-400 is indicated for the reduction in risk of overt hepatic encephalopathy recurrence in patients with advanced chronic liver disease, treatment of traveler's diarrhea caused by noninvasive strains of Escherichia coli, management of irritable bowel syndrome with diarrhea (IBS-D), and small intestinal bacterial overgrowth (SIBO).