Abundance of Hepatic Transporters in Caucasians: A Meta-analysis

The aim of this study was to derive quantitative abundance values for key hepatic transporters suitable for in vitro-in vivo extrapolation (IVIVE) within a physiologically-based pharmacokinetic modeling framework. A meta-analysis was performed whereby abundance measurements, sample preparation method and donor demography were collated from literature. In order to define values for a healthy Caucasian population, […]

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More Power to OATP1B1: An Evaluation of Sample Size in Pharmacogenetic Studies Using a Rosuvastatin PBPK Model for Intestinal, Hepatic, and Renal Transporter-mediated Clearances

Rosuvastatin is a substrate of choice in clinical studies of organic anion-transporting polypeptide (OATP)1B1- and OATP1B3-associated drug interactions; thus, understanding the effect of OATP1B1 polymorphisms on the pharmacokinetics of rosuvastatin is crucial. Here, physiologically-based pharmacokinetic (PBPK) modeling was coupled with a power calculation algorithm to evaluate the influence of sample size on the ability to […]

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Development of a Permeability-limited Model of the Human Brain and Cerebrospinal Fluid (CSF) to Integrate Known Physiological and Biological Knowledge: Estimating Time Varying CSF Drug Concentrations and Their Variability Using In Vitro Data

A 4-compartment permeability-limited brain (4Brain) model consisting of brain blood, brain mass, cranial and spinal cerebrospinal fluid (CSF) compartments has been developed and incorporated into a whole body physiologically-based pharmacokinetic (PBPK) model within the Simcyp Simulator. The model assumptions, structure, governing equations and system parameters are described. The model in particular considers the anatomy and […]

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Breast Cancer Resistance Protein Abundance, but Not mRNA Expression, Correlates with Estron e-3-Sulfate Transport in Caco-2

Transporter mRNA and protein expression data are used to extrapolate in vitro transporter kinetics to in vivo drug disposition predictions. Breast cancer resistance protein (BCRP) possesses broad substrate specificity; therefore, understanding BCRP expression-activity relationships are necessary for the translation to in vivo. Bidirectional transport of estrone-3-sulfate (E-3-S), a BCRP probe, was evaluated with respect to relative BCRP mRNA expression […]

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In Vitro-In Vivo Extrapolation Scaling Factors for Intestinal P-glycoprotein and Breast Cancer Resistance Protein: Part I—A Cross-laboratory Comparison of Transporter-protein Abundances and Relative Expression Factors in Human Intestine and Caco-2 Cells

Over the last 5 years the quantification of transporter-protein absolute abundances has dramatically increased in parallel to the expanded use of in vitro-in vivo extrapolation (IVIVE) and physiologically based pharmacokinetics (PBPK)-linked models, for decision-making in pharmaceutical company drug development pipelines and regulatory submissions. Although several research groups have developed laboratory-specific proteomic workflows, it is unclear if the large range of reported variability is founded […]

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In Vitro-In Vivo Extrapolation Scaling Factors for Intestinal P-glycoprotein and Breast Cancer Resistance Protein: Part II—The Impact of Cross-laboratory Variations of Intestinal Transporter Relative Expression Factors on Predicted Drug Disposition

Relative expression factors (REFs) are used to scale in vitro transporter kinetic data via in vitro-in vivo extrapolation linked to physiologically based pharmacokinetic (IVIVE-PBPK) models to clinical observations. Primarily two techniques to quantify transporter protein expression are available, immunoblotting and liquid chromatography-tandem mass spectrometry. Literature-collated REFs ranged from 0.4 to 5.1 and 1.1 to 90 for intestinal P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), respectively. The impact of using human jejunum-Caco-2 REFs for P-gp (REFiP-gp) and BCRP (REFiBCRP), […]

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Interplay of Metabolism and Transport in Determining Oral Drug Absorption and Gut Wall Metabolism: A Simulation Assessment Using the “Advanced Dissolution, Absorption, Metabolism (ADAM)” Model

Bioavailability of orally administered drugs can be influenced by a number of factors including release from the formulation, dissolution, stability in the gastrointestinal (GI) environment, permeability through the gut wall and first-pass gut wall and hepatic metabolism. Although there are various enzymes in the gut wall which may contribute to gut first pass metabolism, Cytochrome […]

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