Mycophenolic acid trough levels after kidney transplantation in a cyclosporine‐free protocol

Abstract Twenty‐seven stable kidney transplant recipients treated with cyclosporine and prednisone were converted to mycophenolate mofetil (MMF) and prednisone 1 year after transplantation. After conversion the patients were treated with a standard daily dose of 1 g MMF b.i.d. and 10 mg prednisone for 4 months. Thereafter, two MMF dose reductions were performed with a 4‐month interval. Mycophenolic acid (MPA) trough levels were measured at regular intervals. A relation was found between MPA trough levels and MMF dose. The median MPA trough level for patients treated with 1 g MMF b. i. d. was 4.3 μg/ml (0.95‐15.5) and 3.0 μg/ml (0.73‐7.8) for patients treated with 750 mg b. i. d. (P = 0.0002). The MPA trough levels further decreased from 3.0 to 2.3 μg/ml (0.6‐6.63) in patients treated with 500 mg MMF b. i. d. (P = 0.01). Dose reduction of MMF from 1 g to 750 mg b.i.d. could be performed without acute rejections. A further dose reduction to 500 mg b.i.d. elicited 3 rejections. Patients experiencing an acute rejection had a median MPA trough level of 2.3 μg/ml (1.26‐3.38) compared to 3.8 μg/ml (1.48‐6.52) in patients without an acute rejection (P = 0.25). We conclude that there is a significant relation between MPA trough levels and MMF dose. MPA trough levels were not predictive of rejection in the present study.