Mycophenolic Acid Dose Reductions Result in Poor Long-Term Renal Allograft Survival: Comparison Between Mycophenolate Sodium and Mycophenolate Mofetil

Mycophenolate acid (MPA) therapy is associated with a decrease in acute rejection rates and excellent renal allograft survival. Unfortunately, mycophenolate mofetil (MMF) is associated with significant adverse effects (AE), which, in many cases, preclude full-dose therapy. Previously, lower MMF drug exposure was significantly associated with a greater risk of rejection. Patients who had a ≥50% dose reduction of MMF experienced a lower graft survival compared to those who tolerated full-dose MMF. Mycophenolate sodium (MPS) was designed to lessen MPA-associated AE. In this retrospective study, we studied the tolerability and long-term outcomes in renal transplant recipients (RTR) treated with MPS versus MMF. Four hundred forty-nine RTRs who received MPS or MMF for more than 3 months were classified into three groups: group 1: MMF-treated; group 2: MPS-treated; and group 3; patients who converted from MMF to MPS due to AE. Donor and recipient demographics as well as induction and maintenance immunosuppressive therapies were similar in all groups. Patient survival was not different in all groups. However, long-term graft survival was lower in patients whose dose of either MPS or MMF was reduced by ≥50%. Moreover, a ≥50% MPA dose reduction was associated with a higher rate of rejection compared to full dose (38% vs 21%, respectively, P < .01). Compared to patients treated initially with MMF, fewer MPS-treated recipients required dose reductions (65% vs 42%, respectively, P < .001). Furthermore, 38% of patients in group 3 tolerated full-dose MPS despite previous intolerance to MMF. Finally, the long-term graft survival was best in MPS-treated RTR and worst in those who converted from MMF to MPS due to AE. We conclude that MPS is better tolerated than MMF, which may explain the superior graft outcome in RTR who were treated with MPS from the onset.