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 […]

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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 […]

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Metformin and Cimetidine: Physiologically-based Pharmacokinetic Modeling to Investigate Transporter Mediated Drug-drug Interactions

Metformin is used as a probe for OCT2 mediated transport when investigating possible DDIs with new chemical entities. The aim of the current study was to investigate the ability of physiologically–based pharmacokinetic (PBPK) models to simulate the effects of OCT and MATE inhibition by cimetidine on metformin kinetics. PBPK models were developed, incorporating mechanistic kidney […]

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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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Metformin and cimetidine: Physiologically based pharmacokinetic modeling to investigate transporter mediated drug-drug interactions.

Metformin is used as a probe for OCT2 mediated transport when investigating possible DDIs with new chemical entities. The aim of the current study was to investigate the ability of physiologically-based pharmacokinetic (PBPK) models to simulate the effects of OCT and MATE inhibition by cimetidine on metformin kinetics. PBPK models were developed, incorporating mechanistic kidney and […]

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