Correlation Between Mycophenolic Acid Blood Level and Renal Dysfunction in Stable Liver Transplant Recipients Receiving Mycophenolate Monotherapy

Purpose. Mycophenolate mofetil (MMF) is frequently used after liver transplantation (OLT). Mycophenolic acid (MPA) metabolites are eliminated primarily via the kidneys. If renal function declines, clearance is significantly impaired. The aim of this study was to reveal the renal function-dependent changes of MPA level in stable adult OLT recipients receiving MMF monotherapy. Methods. Sixty-five OLT recipients were selected from our OLT database of > 3500 cases. All had undergone MMF monotherapy with a daily MMF dose of 1000 mg or 1500 mg for more than 2 years, primarily because they could not tolerate calcineurin inhibitors. Their clinical profiles, including MPA therapeutic drug monitoring (TDM) and renal function, were analyzed as a cross-sectional study. Results. For the group treated with 1000 mg MMF (n = 40), the 12-hour MPA trough level was 1.20 +/- 0.35 mu g/mL with serum creatinine (Cr) level <= 1.4 mg/dL in 13 patients; it was 2.78 +/- 1.19 mu g/mL with Cr > 1.4 mg/dL in 16 patients not undergoing hemodialysis and 3.83 +/- 0.87 mu g/mL in 11 patients undergoing hemodialysis (P <.001). For the group treated with 1500 mg MMF (n = 25), the MPA trough level was 2.23 +/- 0.99 mu g/mL with Cr <= 1.4 mg/dL in 6 patients; it was 2.81 +/- 0.99 ug/mL with Cr > 1.4 mg/dL in 18 patients not undergoing hemodialysis and 3.5 mu g/mL in 1 patient undergoing hemodialysis (P =.21). Conclusions. Considering the potential therapeutic range of MPA, the suggested MMF dosage for Korean adult OLT recipients requiring hemodialysis may be set around 1000 mg per day. We suggest adjusting the MMF dosage on an individualized basis according to the results of MPA TDM, particularly for patients with markedly impaired renal function.