How Much Infliximab Can You Give to Young Children?

A recent case series (A Assa et al. JPGN 2020; 71: 516-520. Therapeutic Drug Monitoring-guided High-dose Infliximab for Infantile-onset Inflammatory Bowel Disease: A Case Series) describes four infants (2 mo-12 mo) with infantile-onset IBD who received high doses of infliximab.

Treatments regimens utilized infliximab dosing of 10-22 mg/kg/dose with initial three doses over 2-4 weeks. Other prior treatments in these patients included antibiotics (eg. vancomycin/gentamicin) and corticosteroids. Sulfasalazine was administered in two of the patients.

Other Key Points:

  • The authors noted that patients gradually transitioned to every 4 week therapy whild seeking to maintain trough concentrations >10 mcg/mL.
  • Infants have several risk factors for inadequate serum infliximab levels. Infliximab clearance is not linearly weight-related and infants are “most susceptible for under-dosing.”
  • Infliximab distribution in infants & children differs from adults with more peripheral compartment distribution, leading to lower trough levels.
  • Severity of disease impacts infliximab levels and can cause a ‘sink’ effect

The authors note that higher doses may increase adverse events, including infections

My take: This study shows that highly-selected patients may need both accelerated and higher doses of infliximab to enable response. It adds to the literature that children, in general, are at high risk of under-dosing with ‘standard’ infliximab dosing.

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