PI-112 - ESTIMATION OF THE AREA UNDER THE CURVE OF MYCOPHENOLIC ACID CONCENTRATION IN CHINESE PEDIATRIC RENAL TRANSPLANT PATIENTS USING LIMITED SAMPLING METHOD.

S. Li¹, P. Sun²; ¹The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China, ²The first affiliated hospital of sun yat-sen university, guangzhou, guangdong, china.

Background: Monitoring the area under the concentration-time curve (AUC) of the active metabolite mycophenolic acid (MPA) from mycophenolic acid ester (MMF) holds significant clinical importance in tailoring individualized dosing. Limited sampling methods offer a practical solution to the inconvenience of frequent blood draws for AUC calculations in clinical settings. This study aims to establish a limited sampling method for estimating the AUC of MPA in pediatric renal transplant recipients, with the primary objectives of reducing blood draws, cutting treatment costs, and enhancing therapeutic drug monitoring.

Methods: Thirty-five pediatric renal transplant recipients were randomly assigned: 18 to a model group and 17 to a validation group. Blood samples were collected at 0, 0.5, 1, 1.5, 2, 3, 4, 6, 9, and 12 hours post MMF administration. The trapezoidal method was employed to calculate the AUC0-12h of MPA. Multiple linear regression was conducted using MPA-AUC0-12h values against predicted concentrations to develop a predictive equation. The predictive equations were validated with the validation group data using the Bland-Altman plot method to assess agreement and calculate prediction errors.

Results: Six predictive equations were derived The Bland-Altman scatter plot showed strong consistency between the simplified three-point and four-point equations in predicting MPA-AUC0-12h compared to the complete MPA-AUC0-12h . The three-point simplified predictive equation was MPA-AUC0-12h =8.593+1.044C1h+2.412C2h+4.085C12h (r2=0.964, p< 0.001), while the four-point simplified predictive equation was MPA-AUC0-12h =6.451+1.02C1h+2.109C2h+3.014C6h+2.909*C12h (r2=0.977, p< 0.001). The difference of AUC in validation group obtained from the three-point simplified equation compared to the complete AUC was (3.6±19.0) mg·h/L, and for the four-point simplified equation, the difference was (1.8±13.1) mg·h/L

Conclusion: This study provides a relatively simple limited sampling method (1h-2h-12h /1h-2h-6h-12h) for monitoring MPA-AUC in pediatric renal transplant recipients, thoroughly validated in clinical practice, . The three-point simplified equation, significantly reduces the times of blood collection in pediatric patients, while the four-point limited sampling method demonstrates high accuracy and minimal errors.