What are the guidelines for using Rifaximin (Rifaximin) in pediatric patients?

Rifaximin Use in Pediatric Patients

Rifaximin is FDA-approved only for travelers' diarrhea in children ≥12 years of age at 200 mg three times daily for 3 days, with no approved pediatric indications for hepatic encephalopathy or IBS-D. 1

FDA-Approved Pediatric Indication

Travelers' Diarrhea (Age ≥12 years):

• Dosing: 200 mg orally three times daily for 3 days 1
• Indication: Treatment of travelers' diarrhea caused by noninvasive strains of Escherichia coli 1
• Critical limitation: Do NOT use if diarrhea is complicated by fever or bloody stools, or if caused by pathogens other than E. coli 1
• Action required: If diarrhea worsens or persists beyond 24-48 hours, discontinue rifaximin and consider alternative antibiotics 1

Age Restrictions by Indication

• Travelers' diarrhea: Safety and effectiveness NOT established in children <12 years 1
• Hepatic encephalopathy: NOT approved for patients <18 years 1
• IBS-D: NOT approved for patients <18 years 1

Off-Label Pediatric Uses (Limited Evidence)

Inflammatory Bowel Disease (Refractory Cases):

• Rifaximin has been used off-label in younger children with refractory IBD and small intestinal bacterial overgrowth with few reported adverse events 2
• A retrospective pediatric study (n=23, median age 13 years) showed symptom improvement in IBD patients: diarrhea resolved in 60% within 4 weeks, abdominal pain in 70.6%, and bleeding in 66.7% 3
• Dosing range used: 10-30 mg/kg/day, with higher doses showing statistically better results for abdominal pain 3
• Important caveat: The Canadian Association of Gastroenterology made NO recommendation for or against rifaximin in pediatric Crohn's disease due to insufficient evidence, lack of pediatric safety data, and concerns about antimicrobial resistance 4

Recurrent Clostridium difficile Infection:

• May be considered as part of combination therapy for multiple CDI recurrences after standard treatments have failed 2
• This represents off-label use without robust efficacy data 2

Safety Profile in Children

Favorable characteristics:

• Minimal systemic absorption (peak plasma concentrations 0.68-3.4 ng/mL) 1
• Few adverse events reported in pediatric use 2, 3
• Well-tolerated in retrospective pediatric IBD studies 3
• Drug proved safe in young children in general use 5

Concerns and limitations:

• Long-term safety data in children are lacking 2
• Concerns exist regarding antimicrobial resistance development with prolonged use 2
• No serious adverse events reported, but monitoring data for resistant strains during long-term use is still lacking 6

Clinical Failure Scenarios

When rifaximin is NOT appropriate:

• Clinical failure rates reach up to 50% when invasive pathogens are present 2
• NOT appropriate for dysentery treatment, regardless of severity 2
• Rifaximin shows limited efficacy in the aqueous environment of the colon against highly susceptible bacteria 6

Pharmacokinetic Considerations

• Rifaximin is active primarily in the small intestine due to high bile solubility 6
• Virtually non-absorbed with high bioavailability within the GI tract 5
• Intraluminal and fecal drug concentrations largely exceed MIC values against pathogenic organisms 5
• Can be taken with or without food 1

Key Clinical Pitfalls

Avoid these common errors:

• Do not use for systemic bacterial infections due to limited systemic exposure 1
• Do not continue beyond 24-48 hours if symptoms worsen or fail to improve in travelers' diarrhea 1
• Do not use as first-line therapy for inflammatory diarrhea with fever or bloody stools 2, 1
• Exercise caution with concomitant P-glycoprotein inhibitors (e.g., cyclosporine) 1