Overview
Rifaximin is a non-systemic antibiotic that acts locally in the gastrointestinal tract. It is FDA-approved for traveler's diarrhea caused by non-invasive strains of E. coli, reduction in risk of overt hepatic encephalopathy recurrence, and treatment of irritable bowel syndrome with diarrhea (IBS-D) in adults.
Mechanism of Action
Rifaximin is a rifamycin derivative that inhibits bacterial RNA synthesis by binding to the beta-subunit of bacterial DNA-dependent RNA polymerase. It has minimal systemic absorption (<0.4%) and acts locally within the gastrointestinal lumen.
Indications
- Traveler's diarrhea caused by non-invasive strains of Escherichia coli
- Reduction in risk of overt hepatic encephalopathy recurrence in adults
- Treatment of irritable bowel syndrome with diarrhea (IBS-D) in adults
Common Doses
- 200 mg
- 550 mg
Dosage
Traveler's diarrhea: 200 mg three times daily for 3 days. Hepatic encephalopathy: 550 mg twice daily. IBS-D: 550 mg three times daily for 14 days, may be repeated up to two times if symptoms recur.
Contraindications
- Hypersensitivity to rifaximin, any rifamycin antimicrobial agents, or any components of XIFAXAN
Side Effects
- Nausea
- Flatulence
- Headache
- Abdominal pain
- Constipation
- Dizziness
- Fatigue
- Peripheral edema
- Ascites
- Hypersensitivity reactions
Interactions
- Minimal systemic absorption reduces risk of drug-drug interactions
- Theoretical potential for reduced efficacy of oral contraceptives when used with rifaximin
Counseling Points
- Take with or without food as directed
- Complete full course even if symptoms improve
- Report severe diarrhea, abdominal pain, or signs of allergic reaction
- Not for systemic infections due to minimal absorption
- May be used for recurrent IBS-D symptoms under medical supervision