Pharmacokinetic study of mycophenolic acid in Korean kidney transplant patients

The purpose of this study was to characterize the pharmacokinetic parameters of mycophenolic acid (MPA) in Korean kidney transplant recipients. Plasma MPA concentrations of 10 Korean kidney transplant recipients administered a lower dose of mycophenolate mofetil (MMF; 750 mg twice a day) were measured at 2 weeks of MMF therapy by high-performance liquid chromatography (HPLC). The plasma MPA concentration-time curve pattern of patients taking lower doses of MPA was consistent with previously reported profiles of patients taking the fully recommended doses. The plasma MPA concentration-time curve was characterized by an early sharp peak within 1 hour and a small second peak in some patients at 4 to 12 hours postdose. The mean C(max) and AUC were 8.73 +/- 4.65 microg/mL and 18.45 +/- 4.25 microg*h/mL, respectively. The mean fraction of free MPA was 1.60% +/- 0.23%. Patients' age, weight, body surface area, and renal function did not influence the AUC. The free fraction of MPA appeared not to be affected by serum albumin and renal function when creatinine clearance was above 40 mL/min. Regression analysis between each plasma concentration and AUC for the limited sampling strategy of MMF therapeutic drug monitoring demonstrated that the concentrations of predose and 1- and 8-hour postdose were positively correlated with AUC (r = 0.74545, p = 0.0133; r = 0.68485, p = 0.0289; and r = 0.63636, p = 0.0479, respectively). The pattern of the concentration-time profile of MPA in Korean kidney recipients was similar to the results of other studies performed in Caucasians, although there was interindividual variability of AUC, C(max), and t(max). MPA concentrations of predose and 1- and 8-hour postdose were positively correlated with AUC.