Two sampling time profiles for the abbreviated estimation of mycophenolic acid area under the curve in adult renal transplant recipients treated with mycophenolate mofetil and concomitant tacrolimus

Limited sampling strategy of mycophenolic acid in adult kidney transplant recipients: influence of the post-transplant period and the pharmacokinetic profile

We aimed to develop an accurate and convenient LSS for predicting MPA-AUC(0-12 hours) in Tunisian adult kidney transplant recipients whose immunosuppressive regimen consisted of MMF and tacrolimus combination with regards to the post-transplant period and the pharmacokinetic profile. Each pharmacokinetic profile consisted of eight blood samples collected during the 12-hour dosing interval. The AUC(0-12 hours) was calculated according to the linear trapezoidal rule. The MPA concentrations at each sampling time were correlated by a linear regression analysis with the measured AUC(0-12). We analyzed all the developed models for their ability to estimate the MPA-AUC(0-12 hours). The best multilinear regression model for predicting the full MPA-AUC(0-12 hours) was found to be the combination of C1, C4, and C6. All the best correlated models and the most convenient ones were verified to be also applicable before 5 months after transplantation and thereafter. These models were also verified to be applicable for patients having or not the second peak in their pharmacokinetic profiles. For practical reasons we recommend a LSS using C0, C1, and C4 that provides a reasonable MPA-AUC(0-12 hours) estimation.

Diagnostic efficiency of truncated area under the curve from 0 to 2 h (AUC₀₋₂) of mycophenolic acid in kidney transplant recipients receiving mycophenolate mofetil and concomitant tacrolimus

BACKGROUND

Recently, the use of the truncated area under the curve from 0 to 2 h (AUC(0-2)) of mycophenolic acid (MPA) has been proposed for therapeutic monitoring in liver transplant recipients. The aim of our study was the evaluation of the clinical usefulness of truncated AUC(0-2) in kidney transplant patients.

METHODS

Plasma MPA was measured in samples taken before the morning dose of mycophenolate mofetil, and one-half and 2 h post-dose, completing 63 MPA concentration-time profiles from 40 adult kidney transplant recipients. The AUC from 0 to 12 h (AUC(0-12)) was calculated using the validated algorithm of Pawinski et al. The truncated AUC(0-2) was calculated using the linear trapezoidal rule, and extrapolated to 0-12 h (trapezoidal extrapolated AUC(0-12)) as previously described.

RESULTS

Algorithm calculated and trapezoidal extrapolated AUC(0-12) values showed high correlation (r=0.995) and acceptable dispersion (ma68=0.71 μg·h/mL), median prediction error (6.6%) and median absolute prediction error (12.6%). The truncated AUC(0-2) had acceptable diagnostic efficiency (87%) in the classification of subtherapeutic, therapeutic or supratherapeutic values with respect to AUC(0-12). However, due to the high inter-individual variation of the drug absorption-rate, the dispersion between both pharmacokinetic variables (ma68=6.9 μg·h/mL) was unacceptable.

CONCLUSIONS

The substantial dispersion between truncated AUC(0-2) and AUC(0-12) values may be a serious objection for the routine use of MPA AUC(0-2) in clinical practice.