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, … Continued

How Does the In Vivo Biliary Elimination of Drugs Change with Age? Evidence from In Vitro and Clinical Data Using a Systems Pharmacology Approach

Information on the developmental changes in biliary excretion (BE) of drugs is sparse. The aims of this study were to collate literature data on the pharmacokinetics of biliary excretion of drugs used in pediatrics and to apply a physiologically-based pharmacokinetic (PBPK) model to predict their systemic clearance (CL) with a view to elucidating age-related changes … Continued

Considering Age Variation When Coining Drugs as High Versus Low Hepatic Extraction Ratio

The hepatic extraction ratio (EH) is commonly considered an “inherent attribute” of drug. It determines the main physiological and biological elements of the system (patient attributes) that are most significant in interindividual variability of clearance. The EH consists of three age-dependent parameters: fraction of unbound drug in blood (fu.B), hepatic intrinsic clearance of unbound drug … Continued

Prediction of Drug-drug Interactions Arising From CYP3A Induction Using a Physiologically-based Dynamic Model

Using physiologically-based pharmacokinetic modeling, we predicted the magnitude of drug-drug interactions (DDIs) for studies with rifampicin and seven CYP3A4 probe substrates administered i.v. (10 studies) or orally (19 studies). The results showed a tendency to underpredict the DDI magnitude when the victim drug was administered orally. Possible sources of inaccuracy were investigated systematically to determine … Continued

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 … Continued

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), … Continued

Lost in Centrifugation: Accounting for Transporter Protein Losses in Quantitative Targeted Absolute Proteomics

In drug development, considerable efforts are made to extrapolate from in vitro and preclinical findings to predict human drug disposition by using in vitro-in vivo extrapolation (IVIVE) approaches. Use of IVIVE strategies linked with physiologically based pharmacokinetic (PBPK) modeling is widespread, and regulatory agencies are accepting and occasionally requesting model analysis to support licensing submissions. … Continued

Deciding on Success Criteria for Predictability of Pharmacokinetic Parameters from In Vitro Studies: An Analysis Based on In Vivo Observations

Prediction accuracy of pharmacokinetic parameters is often assessed using prediction fold error, i.e., being within 2-, 3-, or n-fold of observed values. However, published studies disagree on which fold error represents an accurate prediction. In addition, “observed data” from only one clinical study are often used as the gold standard for in vitro to in vivo extrapolation (IVIVE) studies, despite data being subject to significant … Continued

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