Pharmacokinetic studies of mycophenolic acid (MPA) were performed in 16 stable Thai kidney transplant recipients treated with 1 g/d of mycophenolate mofetil (MMF). The complete area under the blood concentration-time curve (AUC) of MPA was determined using the linear trapezoidal rule from 8 concentrations at, 0, 1, 2, 3, 4, 6, 8, and 12 h after MMF administration. The mean values of AUC(0-12) were 37.54 + 0.80 microg x h/ml. MPA concentrations at 8 h after dosing, not the trough or maximum levels, showed the best correlation with AUC(0-12) (r2 = 0.72). The equation model of abbreviated AUC of MPA, derived by multiple linear regression analysis, that had the highest correlation (r2) and lowest absolute prediction error (APE) was: AUC = 0.6 C1 + 1.9 C3 + 8.68 C8 + 4.65 (r2 = 0.92, APE = 2.05 +/- 0.32%). The best abbreviated AUC equations obtained by linear trapezoidal rule were: AUC = 4.5 C0 + C1 + 1.5 C2 + 5 C4 (r2 = 0.78, APE = 5.78 +/- 1.14%) and AUC = 5 C0 + C1 + C2 + 5 C3 (r2 = 0.76, APE = 6.21 +/- 1.46%).