In a child on home hemodialysis four times per week, are there any dosing or timing considerations for mycophenolate mofetil, infliximab, or adalimumab regarding removal by dialysis?

Hemodialysis Considerations for MMF, Infliximab, and Adalimumab in Pediatric Patients

All three medications—mycophenolate mofetil (MMF), infliximab, and adalimumab—can be safely used in children on home hemodialysis without dose adjustments, but MMF requires specific timing considerations while the biologics do not.

Mycophenolate Mofetil (MMF)

Dialysis Removal and Timing

MMF itself is not removed by hemodialysis, but its inactive metabolite MPAG (mycophenolic acid glucuronide) accumulates significantly in dialysis patients and is partially dialyzable 1, 2. The parent drug MPA (mycophenolic acid) maintains therapeutic levels despite renal failure 2.

Key dosing considerations:

• Standard dosing applies: 1200 mg/m²/day divided twice daily (maximum 2g/day total) 3, 4
• No dose reduction needed for the dialysis itself
• No specific timing required relative to dialysis sessions—unlike small molecules that are dialyzed out, MMF/MPA is not significantly removed during hemodialysis 2
• The accumulated MPAG metabolite may cause gastrointestinal side effects (nausea, vomiting, abdominal pain), which could limit tolerability 2

Monitoring Requirements

• Target MPA area under the curve >50 μg·h/mL 3
• Watch for GI intolerance—if significant abdominal pain occurs, consider switching to enteric-coated mycophenolic acid formulations 3
• Monitor for bone marrow suppression with regular CBC 4

Infliximab and Adalimumab

Dialysis Removal

Neither infliximab nor adalimumab is removed by hemodialysis due to their large molecular weight (approximately 150 kDa for both monoclonal antibodies) 5. Hemodialysis membranes cannot effectively clear molecules of this size.

Key dosing considerations:

• Standard dosing applies without modification for dialysis 6
• No timing considerations relative to dialysis sessions
• No supplemental doses needed post-dialysis

Specific Dosing Regimens

Infliximab:

• Induction: 5 mg/kg at weeks 0,2, and 6
• Maintenance: 5 mg/kg every 8 weeks
• May increase to 10 mg/kg or shorten interval to every 4 weeks if losing response 6

Adalimumab (pediatric dosing):

• For patients <40 kg: 80 mg at week 0,40 mg at week 2, then 20 mg every other week
• For patients ≥40 kg: 160 mg at week 0,80 mg at week 2, then 40 mg every other week 6, 5
• May increase to weekly dosing if losing response

Common Pitfalls to Avoid

1. Do not reduce MMF dose based solely on dialysis status—the active drug is not removed
2. Do not time biologic administration around dialysis sessions—this is unnecessary and creates logistical burden
3. Do not assume MPAG accumulation requires dose reduction—instead, monitor for GI side effects and consider formulation change if needed
4. Screen for tuberculosis before starting anti-TNF therapy (mandatory) 6, 3
5. Check hepatitis B status before rituximab or anti-TNF therapy 3

Practical Implementation

For this child on 4x/week home hemodialysis:

• MMF: Give standard weight/BSA-based dosing twice daily, independent of dialysis timing
• Infliximab or Adalimumab: Administer on standard schedule without regard to dialysis days
• All three can be used safely in combination with appropriate monitoring
• The rheumatologist can proceed with standard protocols without dialysis-specific modifications beyond awareness of MPAG accumulation with MMF

The evidence base for these recommendations comes from pharmacokinetic studies demonstrating minimal to no dialytic clearance of these agents 1, 2, FDA labeling that does not require dose adjustment for renal impairment 5, 4, and pediatric nephrology guidelines that use standard dosing in dialysis-dependent children 3.