Typical Dosage and Use of Cellcept (Mycophenolate Mofetil) in Transplant Patients
The standard dosage of mycophenolate mofetil (MMF) for preventing organ rejection in adult kidney transplant recipients is 1 gram twice daily, administered as part of a triple immunosuppressive regimen with calcineurin inhibitors (preferably tacrolimus) and corticosteroids. 1
Mechanism of Action and Role
Mycophenolate mofetil is an antimetabolite immunosuppressant that:
- Acts as a prodrug of mycophenolic acid
- Inhibits inosine monophosphate dehydrogenase (IMPDH), a key enzyme in de novo purine synthesis
- Selectively inhibits T and B lymphocyte proliferation
- Prevents organ rejection by blocking lymphocyte proliferation 1, 2
Dosing Guidelines by Transplant Type
Kidney Transplantation
- Adult dose: 1 gram twice daily (2 g total daily dose) 1, 3
- Pediatric dose: 600-1200 mg/m² daily, divided into two doses 4
- Administered orally in combination with tacrolimus and corticosteroids
- Lower doses (1 g/day) may provide optimal balance of efficacy and safety when used with tacrolimus 3
Heart Transplantation
- Adult dose: 1.5 g twice daily (3 g total daily dose)
- Used in combination with cyclosporine or tacrolimus and corticosteroids
Liver Transplantation
- Adult dose: 1 g twice daily (2 g total daily dose)
- Used in combination with tacrolimus or cyclosporine and corticosteroids
Administration and Formulations
MMF is available in multiple formulations:
- Oral capsules (250 mg)
- Oral tablets
- Oral suspension
- Administered twice daily 4
Monitoring Requirements
Regular monitoring is essential:
- Measure MMF blood levels as suggested by guidelines 4
- Monitor complete blood count regularly for bone marrow suppression
- Check renal function:
- Daily for first 7 days post-transplant
- 2-3 times weekly for weeks 2-4
- Weekly for months 2-3
- Every 2 weeks for months 4-6
- Monthly for months 7-12
- Every 2-3 months thereafter 4
- Monitor urine protein excretion:
- Once in first month for baseline
- Every 3 months during first year
- Annually thereafter 4
Common Adverse Effects
- Gastrointestinal: Nausea, vomiting, diarrhea, abdominal cramping (most common) 4, 1
- May improve with enteric-coated formulation
- Not dose-dependent
- Hematologic: Leukopenia, anemia, thrombocytopenia 4, 1
- Increased infection risk: Particularly viral and opportunistic infections 1
Important Drug Interactions
- Decreased MMF levels with:
- Antacids containing magnesium/aluminum
- Cholestyramine
- Rifampin 1
- Increased toxicity when combined with other immunosuppressants
- Avoid combining with azathioprine due to overlapping mechanisms and toxicity 4
Special Considerations
- Pregnancy: FDA black box warning due to increased risk of miscarriage (49%) and birth defects (23%) 1
- Generic substitution: Use only adequately tested bioequivalent generic drugs 4
- Monitoring after switching to generic: Obtain blood levels frequently until stable therapeutic target is achieved 4
Efficacy in Transplantation
MMF has demonstrated superior efficacy compared to azathioprine in preventing acute rejection in the first year after transplantation 2, 5. When used with low-dose tacrolimus, a 1 g daily dose of MMF provides an optimized efficacy and safety profile, while a 2 g daily dose may cause greater toxicity without significant improvement in efficacy 3.
Pitfalls to Avoid
- Don't use MMF as monotherapy; it's not potent enough alone but is an important adjunct agent 1
- Monitor for GI symptoms, which are common but manageable
- Be vigilant about infection risk, especially opportunistic infections
- Avoid combining with other myelosuppressive drugs without careful monitoring
- Consider drug interactions when prescribing other medications
MMF remains a cornerstone of modern transplant immunosuppression regimens, providing effective rejection prophylaxis when used appropriately as part of a multi-drug regimen.