What are the uses and dosing of Rifaximine (Rifaximin)?

Rifaximin Uses and Dosing

Rifaximin is primarily indicated for travelers' diarrhea, hepatic encephalopathy, and irritable bowel syndrome with diarrhea (IBS-D), with specific dosing regimens for each condition. 1, 2

Primary Indications and Dosing

Travelers' Diarrhea

• Dosage: 200 mg three times daily for 3 days 2
• Most effective against Escherichia coli-related diarrhea 2
• Less effective in South/Southeast Asia where Campylobacter (resistant to rifaximin) is more common 3
• Not recommended for diarrhea with fever or blood in stool (dysentery) due to lower efficacy 2

Hepatic Encephalopathy

• Dosage: 550 mg twice daily 1
• Used as add-on therapy to lactulose after second episode of overt hepatic encephalopathy 1
• Combination therapy reduces recurrence risk by 58% compared to lactulose alone 1
• Long-term maintenance therapy is appropriate for prevention of recurrence 1

Irritable Bowel Syndrome with Diarrhea (IBS-D)

• Dosage: 550 mg three times daily for 14 days 1
• Recommended as second-line treatment in secondary care 1
• Monitor for 30% reduction in abdominal pain and improvement in stool consistency 1

Additional Uses

Small Intestinal Bacterial Overgrowth (SIBO)

• Dosage: 550 mg three times daily for 14 days 1

Clostridium difficile Infection

• May be considered for pediatric patients with multiple recurrences following standard antibiotic treatments 3
• Not a first-line treatment; used when conventional treatments have failed 3

Pharmacology and Safety Profile

• Mechanism: Binds to bacterial DNA-dependent RNA polymerase, inhibiting bacterial protein synthesis 2
• Poorly absorbed from gastrointestinal tract (<0.4%), making it ideal for treating local GI conditions 4
• Minimal systemic side effects due to negligible absorption 3, 1
• Low risk of bacterial resistance development with long-term use 1

Special Considerations

Pediatric Use

• Safety and effectiveness not established in children <12 years for travelers' diarrhea 2
• Not established in patients <18 years for hepatic encephalopathy and IBS-D 2

Pregnancy

• Limited data in pregnant women; animal studies showed teratogenic effects 2
• Potential risk to fetus; use only if benefit outweighs risk 2

Drug Interactions

• Monitor INR and prothrombin time when used with warfarin 2
• May affect oral contraceptive efficacy; C₍max₎ of ethinyl estradiol reduced by 25% 2
• Use caution with P-glycoprotein inhibitors like cyclosporine 2

Contraindications and Precautions

• Hypersensitivity to rifaximin, rifamycin antimicrobial agents, or components of the formulation 2
• Use with caution in severe hepatic impairment (Child-Pugh Class C) 1
• Monitor for Clostridium difficile-associated diarrhea 1, 2

Clinical Pearls

• Rifaximin is ineffective against Campylobacter jejuni infections 4
• For hepatic encephalopathy, always consider as add-on to lactulose rather than monotherapy 1
• Not recommended for routine prophylaxis after TIPS placement 1
• High cost may impact long-term adherence 1

Rifaximin's unique properties as a non-absorbed antibiotic make it particularly valuable for treating localized gastrointestinal infections with minimal systemic effects, though appropriate patient selection based on likely pathogens and clinical presentation is essential for optimal outcomes.