Mycophenolic acid plasma concentrations in kidney allograft recipients with or without cyclosporin: a cross-sectional study

Background. Combining cyclosporin (CsA) and prednisone with mycophenolate m ofetil (MMF) results in a significant reduction in the rate of biopsy-prove n acute rejection after kidney transplantation. This is achieved with a sta ndard daily MMF dosage of 2 or 3g. Whether monitoring of the pharmacologica lly active metabolite mycophenolic acid (MPA) will lead to improved safety and efficacy is unclear. Methods. We monitored MPA trough levels in Is kidney transplant recipients treated with CsA, prednisone, and MMF (63 samples) and in 11 patients (31 s amples) treated with prednisone and MMF only, in a cross-sectional study. A ll patients were at least 3 months after transplantation with stable graft function. All patients were treated with 2 g MMF for at least 3 months and 10 mg prednisone. Results. The MPA trough levels in the CsA-treated patients were significant ly lower (P<0.0001; Mann-Whitney) than those in patients on MMF and prednis one only (mean MPA levels 1.98+/-0.12 vs 4.38 +/- 0.40 mg/l respectively). Conclusions. Although all patients were treated with an identical MMF dose, a significant difference was found in the MPA trough levels between CsA- v s non-CsA-treated patients. This suggests that: CsA influences the MPA trou gh level. The level at which CsA affects the MPA trough levels is unclear.