Background: Oral iron supplements are frequently prescribed to renal transplant recipients in the early posttransplant period. A recent trial in seven healthy volunteers demonstrated a significant 91% reduction in mycophenolate mofetil (MMF) absorption when coadministered with oral iron. However, the effect of iron on MMF absorption in renal transplant patients has not been studied.
Methods: An open-label, randomized, controlled trial was undertaken in which new renal transplant recipients were randomly allocated to receive iron supplements with a morning dose of MMF, iron supplements given 4 hr after MMF at midday, or no iron supplements. Blood samples were taken for estimation of mycophenolic acid (MPA) area under the curve (AUC) at day 5 posttransplant. The primary endpoint was the day 5 MPA AUC, with secondary endpoints including acute rejection and MMF toxicity in the first 4 weeks posttransplant. Prospective power calculations indicated that a minimum of 13 patients in each group would be required to have a 90% probability of detecting a clinically significant reduction (10 mg/hr/L) in MPA AUC for iron-treated patients.
Results: Forty patients completed the study. There were no differences in baseline demographic data between the groups. The mean+/-standard deviation MPA AUC measurements for the groups receiving no iron (n=13), iron and MMF together (n=14), and iron and MMF spaced apart (n=13) were 34.5+/-8.7, 33.7+/-11.4, and 32.1+/-8.1 microg/hr/mL, respectively (P=0.82). Rates of acute rejection, cytopenia, infection, and gastrointestinal intolerance were comparable between the groups.
Conclusions: There is no significant effect of oral iron supplements on MMF absorption as determined by measured blood concentrations. The practice of routinely giving oral iron in such patients seems safe from an immunosuppression drug-interaction standpoint.