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Non linear mixed effects analysis in PET PK-receptor occupancy studies
Alienor Berges1, Vincent J Cunningham, Roger N Gunn
1GlaxoSmithKline, Clinical Pharmacology Modelling & Simulation, Stockley Park, UK. alienor.c.berges@gsk.com
Non-linear mixed effects (NLME) modeling offers a more robust approach than non-linear least squares (NLLS) for pharmacokinetic-receptor occupancy (PK-RO) relationships. NLME improves estimation of between-subject variability, especially in complex scenarios without reference regions.
Area of Science:
- Pharmacology
- Radiopharmaceutical Sciences
- Biostatistics
Background:
- Pharmacokinetic-receptor occupancy (PK-RO) relationships are crucial for drug development.
- Conventional modeling often uses non-linear least squares (NLLS).
- The performance of NLLS can be limited by data variability and model complexity.
Purpose of the Study:
- To compare the performance of non-linear mixed effects (NLME) modeling against NLLS for PK-RO relationships.
- To evaluate the impact of between-subject variability and reference region availability on estimation accuracy.
- To assess the robustness and precision of NLME versus NLLS using simulated PET data.
Main Methods:
- Simulated positron emission tomography (PET) data using a two-tissue compartmental model and an Emax model for PK-RO.
- Applied both NLME and NLLS (naive pooled and two-stage) estimation methods.
- Compared parameter estimates (SME, RMSE) and prediction accuracy across various PET scenarios.
Main Results:
- Both NLME and NLLS provided unbiased population estimates for Emax model parameters.
- NLME demonstrated superior performance in estimating between-subject variability (BSV), particularly when no reference region was available.
- NLLS showed slight bias in individual estimates due to outliers, while NLME was more robust.
Conclusions:
- NLME is a more robust and accurate method for characterizing PK-RO relationships compared to NLLS.
- NLME excels in estimating population variances and handling complex models with limited reference data.
- The findings support the adoption of NLME for improved PK-RO modeling in PET studies.
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