Rifaximin is a semisynthetic, rifamycin-based non-systemic antibiotic. Very little of the drug will pass the gastrointestinal wall into the circulation as is common for other types of orally administered antibiotics. Rifaximin inhibits bacterial RNA synthesis by its action on the beta-subunit of the DNA-dependent RNA polymerase. It shows the same broad spectrum activity as rifamycin which exerts bactericidal action against many species of Gram-positive and Gram-negative, aerobic and anaerobic bacteria.

Rifaximin is indicaed in-

• Treatment of traveler's diarrhea by noninvasive strains of E. coli
• reduction in risk of overt hepatic encephalopathy
• bacterial overgrowth of irritable bowel syndrome.

Traveler's Diarrhea: For patients ≥12 years of age: 200 mg 3 times daily for 3 days.

Hepatic Encephalopathy: For patients ≥18 years of age: 550 mg 2 times daily.

Bacterial overgrowth of irritable bowel syndrome: 400 mg 3 times daily for 10 days or 550 mg 3 times daily for 14 days. Can be taken with or without food

Contraindicated in patients with a hypersensitivity to Rifaximin or to any of the rifamycin antimicrobial agents, or any components of this product

Side effects include flatulence, headache, abdominal pain, rectal tenesmus, defecation urgency, nausea, constipation, pyrexia, vomiting. Reactions have been reported, including anaphylaxis, angioneurotic edema, and exfoliative dermatitis.

Overdose Effects

No specific information is available on the treatment of over dosage with Rifaximin. In case of over dosage, discontinue Rifaximin, treat symptomatically and institute supportive measures as required.

Rifaximin is not found to be effective in patients with diarrhea complicated by fever and/or blood in the stools. Rifaximin therapy should be discontinued if diarrhea symptoms get worse or persist for more than 24-48 hours and alternative antibiotic therapy should be considered. Pseudomembranous colitis has been reported with nearly all antibacterial agents and may range in severity from mild to life-threatening. Therefore, it is important to consider this diagnosis in patients who present with diarrhea subsequent to the administration of antibacterial agents.

Use in Special Populations

Renal Impairment: The pharmacokinetics of Rifaximin in patients with impaired renal function has not been studied.

Hepatic Impairment: The systemic exposure of Rifaximin was markedly elevated in patients with hepatic impairment compared to healthy subjects.

Pregnancy & Lactation

Pregnancy category C. It is not known whether Rifaximin is excreted in human milk or not.