FDA Indications for Rifaximin
Rifaximin (Xifaxan) is FDA-approved for three specific indications: treatment of travelers' diarrhea caused by noninvasive strains of Escherichia coli in patients 12 years and older, reduction in risk of overt hepatic encephalopathy recurrence in adults, and treatment of irritable bowel syndrome with diarrhea (IBS-D) in adults. 1
Detailed FDA Indications
1. Travelers' Diarrhea
- Approved population: Adults and pediatric patients 12 years of age and older
- Specific indication: Treatment of travelers' diarrhea caused by noninvasive strains of Escherichia coli
- Important limitations: Not indicated for diarrhea complicated by fever or blood in the stool, or diarrhea due to pathogens other than E. coli 1
- Recommended dosage: 200 mg three times daily for 3 days 2
2. Hepatic Encephalopathy
- Approved population: Adults (18 years and older)
- Specific indication: Reduction in risk of overt hepatic encephalopathy recurrence
- Recommended dosage: 550 mg twice daily 3
- Clinical use: Typically used as an add-on to lactulose after a second episode of hepatic encephalopathy, particularly when precipitating factors have been controlled 3
3. Irritable Bowel Syndrome with Diarrhea (IBS-D)
- Approved population: Adults
- Specific indication: Treatment of irritable bowel syndrome with diarrhea
- Recommended dosage: 550 mg three times a day for 14 days 3
Clinical Considerations
Pharmacological Properties
- Rifaximin is a semisynthetic rifamycin derivative with minimal systemic absorption (<0.4%) 4
- Its gastrointestinal-selective nature makes it particularly suitable for treating localized GI infections with minimal systemic effects 5
Efficacy
- For travelers' diarrhea: Comparable efficacy to ciprofloxacin in reducing duration of diarrhea after treatment initiation 6
- For hepatic encephalopathy: Reduces mortality (RR: 0.50; 95% CI, 0.31–0.82) and improves recovery rates (RR: 0.59; 95% CI, 0.46–0.76) 3
Safety Considerations
- Rifaximin has an excellent safety profile due to minimal systemic absorption 5
- Should be used with caution in patients with severe hepatic impairment (Child-Pugh Class C) 3
- Monitor for Clostridium difficile-associated diarrhea, though risk is lower than with systemic antibiotics 3
Antimicrobial Resistance
- Unlike systemically absorbed antibiotics, acquisition of resistance to rifaximin would have limited consequences for global public health 4
- However, potential for cross-resistance between rifaximin and rifampin exists and requires monitoring 7
Off-Label Uses
While not FDA-approved for these indications, rifaximin has been studied for:
- Prevention of travelers' diarrhea 4
- Small intestinal bacterial overgrowth 5
- Clostridium difficile infection 5
- Inflammatory bowel disease 5
- Diverticular disease 5
Remember that rifaximin should not be used for travelers' diarrhea caused by invasive pathogens, as it has shown inefficacy in these cases 4. For dysentery or febrile diarrhea, alternative antibiotics such as azithromycin are preferred 2.