What is the dosage and treatment regimen for Xifaxin (Rifaximin)?

Rifaximin (Xifaxin) Dosage and Treatment Regimen

The recommended dosage and treatment regimen for Xifaxin (rifaximin) varies by indication: for hepatic encephalopathy, 550 mg twice daily; for irritable bowel syndrome with diarrhea (IBS-D), 550 mg three times daily for 14 days; and for travelers' diarrhea, 200 mg three times daily for 3 days. 1

Dosage by Indication

Hepatic Encephalopathy

• Dosage: 550 mg twice daily 1
• Duration: Long-term/maintenance therapy 2
• Administration: Can be taken with or without food 1
• Use: As add-on therapy to lactulose or alone in patients who cannot tolerate lactulose 2
• Efficacy: Reduces risk of recurrence of hepatic encephalopathy by 58% compared to placebo (hazard ratio 0.42,95% CI 0.28-0.64, p<0.001) 2, 3

Irritable Bowel Syndrome with Diarrhea (IBS-D)

• Dosage: 550 mg three times daily 1
• Duration: 14 days 1
• Retreatment: Patients who experience symptom recurrence can be retreated up to 2 times with the same regimen 1
• Administration: Can be taken with or without food 1
• Use: Second-line drug in secondary care 2

Travelers' Diarrhea

• Dosage: 200 mg three times daily 1
• Duration: 3 days 1
• Administration: Can be taken with or without food 1
• Limitations: Only for diarrhea caused by noninvasive strains of Escherichia coli; not for use in patients with diarrhea complicated by fever or blood in the stool 1

Monitoring and Response Evaluation

Clinical Response Assessment

• Evaluate clinical improvement during the first 4 weeks after treatment initiation 2
• For IBS-D, monitor for:
  • 30% reduction from baseline in worst abdominal pain scores
  • Improvement to Bristol Stool Form Scale score <5
  • 30% improvement in average bloating scores
  • Reduction in percentage of days with urgency 2

Safety Monitoring

• No routine laboratory monitoring required for efficacy or toxicity 2
• Monitor clinically for symptom response and potential adverse effects 2
• For patients on warfarin, monitor INR and prothrombin time as dose adjustments may be needed 1

Special Considerations

Hepatic Impairment

• Use with caution in patients with severe hepatic impairment (Child-Pugh Class C) 2, 1

Drug Interactions

• Exercise caution when using concomitantly with P-glycoprotein inhibitors (e.g., cyclosporine) 1
• Monitor patients on warfarin for potential interactions 2, 1

Long-term Safety

• Long-term rifaximin use has not shown increased risk of bacterial resistance or Clostridium difficile-associated colitis 2, 4
• Safety profile in long-term studies (≥24 months) remains similar to short-term use 4

Common Adverse Effects

• Hepatic encephalopathy treatment: peripheral edema, nausea, dizziness, fatigue, and ascites (≥10%) 1
• IBS-D treatment: ALT increased, nausea (≥2%) 1
• Travelers' diarrhea treatment: headache (≥2%) 1

Rifaximin has demonstrated effectiveness in maintaining remission from hepatic encephalopathy and reducing related hospitalizations, with a favorable safety profile even with extended use 3, 4. For IBS-D, it provides relief of global symptoms and bloating 5. The medication can be taken with or without food, making it convenient for patient use 1.