Killing several birds with one stone: A multi-indication population pharmacokinetic model and Bayesian estimator for
Yeleen Fromage1, Hamza Sayadi1, Kevin Koloskoff2,3
1Department of Pharmacology, Toxicology and Pharmacovigilance, CHU de Limoges, Limoges, France.
Aims:
Mycophenolic acid (MPA), the active component of enteric-coated mycophenolate sodium (EC-MPS), exhibits highly variable pharmacokinetics. Only a few population pharmacokinetic (popPK) models and Bayesian estimators (MAP-BE) exist for estimating MPA AUC and all in renal transplantation. This study aimed to develop a popPK model and MAP-BE for MPA AUC estimation using a limited sampling strategy (LSS) in solid organ transplant (SOT), haematopoietic stem cell (HSC) recipients and patients with autoimmune diseases (AID) on EC-MPS.
Methods:
Full and sparse MPA pharmacokinetic profiles were extracted from our ISBA system, split into development (75%) and validation (25%) sets. An additional extraction was performed after the modelling process for external validation. Pharmacokinetic parameters were estimated using Monolix® (SAEM algorithm). Several absorption models (first order, transit, gamma) were compared. AUCpredicted by MAP-BE and LSS was compared to the all-sample MAP-BE AUCreference using Simulx®.
Results:
We included 153 PK profiles (863 concentration) from 129 patients (116 SOT and HSC, 13 AID), median [min-max] age 45 years [6-80]. A one-compartment model with double-gamma absorption and first-order elimination best fitted the data. The final model included the EC-MPS indication and inter-occasion variability on gamma rate constants. Main PK parameters (mean ± SD) were Cl/F = 4.99 ± 2.22 L/h and Vd/F = 12.60 ± 0.08 L. The optimal LSS at 20 min, 2 h and 4 h post-dose showed good performance in both validation sets (rMPE -2.67% and -4.91%; RMSE 13.55% and 13.47%).
Conclusions:
The double-gamma absorption model provided an accurate fit. The MAP-BE offers a tool for EC-MPS dose individualization in SOT, HSC and AID patients.
Insights
This study developed a population pharmacokinetic model for mycophenolic acid (MPA) using a limited sampling strategy. The model accurately estimates MPA AUC for personalized dosing in transplant and autoimmune disease patients.
Area of Science:
- Pharmacokinetics
- Drug Metabolism and Disposition
- Clinical Pharmacology
Background:
- Mycophenolic acid (MPA) pharmacokinetics are highly variable.
- Existing population pharmacokinetic (popPK) models for MPA are limited, especially for estimating AUC in specific patient populations.
- Enteric-coated mycophenolate sodium (EC-MPS) is widely used but requires precise dosing due to variable MPA levels.
Purpose of the Study:
- To develop a popPK model for MPA.
- To create a Bayesian estimation (MAP-BE) method for MPA AUC using a limited sampling strategy (LSS).
- To validate the model and LSS in solid organ transplant (SOT), hematopoietic stem cell (HSC), and autoimmune disease (AID) patients.
Main Methods:
- PK profiles were extracted and split into development and validation sets.
- A one-compartment model with double-gamma absorption was selected using the SAEM algorithm.
- MAP-BE and LSS were used to predict MPA AUC and compared against reference values.
Main Results:
- A one-compartment model with double-gamma absorption and first-order elimination best described MPA PK.
- The optimal LSS included samples at 20 min, 2 h, and 4 h post-dose.
- The LSS demonstrated good performance in validation sets with low prediction error (rMPE -2.67% to -4.91%) and RMSE (13.55% to 13.47%).
Conclusions:
- The developed double-gamma absorption model accurately fits MPA PK data.
- The MAP-BE with LSS provides a reliable tool for individualizing EC-MPS (MPA) dosage.
- This approach supports optimized MPA dosing in SOT, HSC, and AID patients.
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