Mycophenolic acid trough level measurements and clinical outcomes in kidney transplantation recipients on a fixed dose (1.5 g/d) of Mycophenolate mofetil in Korea

Background Mycophenolate mofetil (MMF) is routinely used at a fixed dose, but several factors interact to alter the blood level of mycophenolic acid (MPA), resulting in toxicity or treatment failure. Methods From January 2007 to December 2008, 85 kidney transplantation patients were given a fixed dose of 1.5 g/d of MMF in 12-hour intervals. MPA trough levels were measured on postoperative 1 week, 1 month, 3 months, 6 months, and 12 months. Results Mean age of patients was 41 years. Thirty five cases were deceased donor kidney transplantations and 50 were living donor kidney transplantations. Mean trough levels of MPA were 1.04 μg/mL, 1.09 μg/mL, 1.28 μg/mL, 1.83 μg/mL, and 1.69 μg/mL at postoperative 1 week, 1 month, 3 months, 6 months, and 12 months, respectively. Mean trough levels of the subgroup of patients taking cyclosporine were 0.82 μg/mL, 0.94 μg/mL, 1.01 μg/mL, 1.56 μg/mL, and 1.46 μg/mL (n = 36). Mean trough levels of the subgroup of patients taking tacrolimus were 1.19 μg/mL, 1.21 μg/mL, 1.56 μg/mL, 2.13 μg/mL, and 2.20 μg/mL (n = 49). At 12 months, 31% of all patients experienced one or more opportunistic infections. Eight patients (9.4%) had cytomegalovirus infections, 14 patients (16.5%) had polyomavirus infections, and four patients (4.7%) had parvovirus infections. Ten patients (11.8%) experienced biopsy-proven acute rejection during the follow-up period. Conclusion Mean MPA trough levels of patients on 1.5 g/d of MMF reached 1.0 μg/mL within 1 week. Thirty one percent of patients experienced opportunistic infections, and 11.8% of patients had biopsy-proven acute rejections.