What is the recommended dosing for CellCept (Mycophenolate Mofetil) in patients with Microscopic Polyangiitis-Interstitial Lung Disease (MPA-ILD)?

Recommended CellCept Dosing for MPA-ILD

For patients with Microscopic Polyangiitis-Interstitial Lung Disease (MPA-ILD), the recommended dosing of CellCept (mycophenolate mofetil) is 1,500 mg twice daily (3 g total daily dose) for optimal management of the interstitial lung disease component. 1

Initial Dosing and Titration

• Start at 500 mg twice daily for 1-2 weeks
• Increase to 1,000 mg twice daily for 1-2 weeks
• Target maintenance dose: 1,500 mg twice daily (3 g total daily dose)
• For Asian patients, consider a lower target dose of 1,000 mg twice daily (2 g total daily dose) 1

Monitoring Schedule

• Complete blood count (CBC): Weekly for first month, twice monthly for second and third months, then monthly for remainder of first year 1
• Renal and hepatic function tests: Every 1-3 months while on therapy 1
• Consider MPA blood level monitoring if:
  • Signs of GI intolerance develop (especially diarrhea)
  • Inadequate clinical response
  • Suspected drug interactions 1

Duration of Therapy

• Minimum treatment duration: 36 months (3 years) 1
• Maintain target dose until achievement of complete response, then consider gradual tapering 1

Special Considerations

Drug Interactions

• Avoid concurrent use with:
  • Azathioprine (increased inhibition of purine metabolism)
  • Activated charcoal, aluminum/magnesium antacids, cholestyramine, iron supplements (reduced absorption) 1
• Caution with proton pump inhibitors (PPIs) and H2 receptor blockers:
  • Esomeprazole can reduce MPA bioavailability by 32.7%
  • Ranitidine can reduce MPA bioavailability by 22% 2
  • Consider separating administration times or monitoring drug levels

Dose Adjustments

• Renal impairment: Consider dose reduction and more frequent monitoring 1
• Gastrointestinal intolerance: Consider temporary dose reduction or divided dosing
• If using mycophenolic acid (MPA) instead of MMF: 1,080-1,440 mg twice daily (equivalent to 1,500-2,000 mg MMF twice daily) 1

Safety Warnings

• Pregnancy: Contraindicated (FDA black box warning) - use effective contraception 1
• Infection risk: Monitor for signs of infection (fever, cough, urinary symptoms)
• Malignancy risk: Annual skin examination recommended

Efficacy Assessment

• Allow 3-6 months to assess initial clinical response
• Monitor pulmonary function tests (FVC, DLCO) every 3-6 months
• Consider repeat HRCT chest at 6-12 months to assess response

Common Pitfalls

1. Inadequate dosing - underdosing is common but reduces efficacy
2. Premature discontinuation before reaching therapeutic effect (minimum 3-6 months needed)
3. Failure to monitor for drug interactions, especially with acid-suppressing medications
4. Inadequate monitoring of blood counts, leading to undetected cytopenias
5. Not separating MMF administration from medications that impair absorption

By following this dosing regimen and monitoring schedule, optimal management of MPA-ILD can be achieved while minimizing potential adverse effects.