Therapeutic Drug Monitoring of Mycophenolic Acid in Renal Transplant Recipients

Abstract

Immunosuppressive regimens including mycophenolate mofetil (MMF, Cellcept) were used in a renal transplant transplant program since May 2000 including 67 patients in whom it was the primary drug. Acute rejection (AR) occurred in 9 cases (13%) with 1-year graft survival rate of 96.8%. Pharmacokinetic (PK) studies of mycophenolic acid (MPA) were performed in 46 recent patients (total, 127 times). There was no correlation between dose (mg/kg) and blood concentration (AUC 0–9: r 2 = 0.27). AUC 0–9 was well correlated with AUC 0–4 ( r 2 = 0.91), but not with a single timepoint concentration. MPA AUC 0–9 level was significantly higher among the AR-negative group (n = 33; 34.2 ± 16.8 ng · hr/mL) compared with AR-positive group (n = 3; 28.2 ± 1.9 ng · hr/mL; P = .04085) over the 2 weeks after transplantation. MPA AUC 0–9 level was higher among the adverse event (AE-positive) group (n = 15; 39.2 ± 22.8 ng · hr/mL) compared with the negative group (n = 21; 30.1 ± 8.0 ng · hr/mL; P = .08772) within 2 weeks after transplantation. These results suggest the necessity of measuring AUC for therapeutic drug monitoring (TDM) of MMF-containing immunosuppressive therapy. The possible target level of MPA AUC 0–9 would be approximately 30 ng · hr/mL using the present immunosuppressive regimen.