Physiologically-based Pharmacokinetics in Drug Development and Regulatory Science

The application of physiologically-based pharmacokinetic (PBPK) modeling is coming of age in drug development and regulation, reflecting significant advances over the past 10 years in the predictability of key pharmacokinetic (PK) parameters from human in vitro data and in the availability of dedicated software platforms and associated databases. Specific advances and contemporary challenges with respect […]

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Assessment of Algorithms for Predicting Drug-drug Interactions Via Inhibition Mechanisms: Comparison of Dynamic and Static Models

The prediction of drug-drug interactions (DDIs) from in vitro data usually utilizes an average dosing interval estimate of inhibitor concentration in an equation-based static model. Simcyp®, a population-based ADME simulator, is becoming widely used for the prediction of DDIs and has the ability to incorporate the time-course of inhibitor concentration and hence generate a temporal […]

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Physiologically-based Mechanistic Modeling to Predict Complex Drug–drug Interactions Involving Simultaneous Competitive and Time-dependent Enzyme Inhibition by Parent Compound and Its Metabolite in Both Liver and Gut—The Effect of Diltiazem on the Time-course of Exposure to Triazolam

The aim of this study was to predict the magnitude of metabolic drug-drug interaction (mDDI) between triazolam and diltiazem and its primary metabolite N-desmethyldiltiazem (MA).Relevant in vitro metabolic and inhibitory data were incorporated into a mechanistic physiologically based pharmacokinetic model within Simcyp (Version 9.1) to simulate the time-course of changes in active CYP3A4 content in […]

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A Semi-mechanistic Model to Predict the Effects of Liver Cirrhosis on Drug Clearance

Liver cirrhosis is characterized by a decrease in functional hepatocytes, lowered circulating levels of plasma proteins and alterations in blood flow due to the development of portacaval shunts. Depending on the interplay between these parameters and the characteristics of an administered drug, varying degrees of impaired systemic clearance and first-pass metabolism are anticipated. The Simcyp® […]

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Assessing the Efficiency of Mixed Effects Modeling in Quantifying Metabolism-based Drug-drug Interactions: Using In Vitro Data as an Aid to Assess Study Power

The clinical assessment of metabolic drug-drug interactions (mDDI) may involve population-based pharmacokinetic (POPPK) assessment as part of Phase 3 clinical trials. The elements of such POPPK study design have not been linked to prior information from in vitro experiments. Using in vitro-in vivo extrapolation techniques, implemented within Simcyp algorithms, the influence of POPPK study design […]

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Population-based Mechanistic Prediction of Oral Drug Absorption

The bioavailability of drugs from oral formulations is influenced by many physiological factors including gastrointestinal fluid composition, pH and dynamics, transit and motility, and metabolism and transport, each of which may vary with age, gender, race, food, and disease. Therefore, oral bioavailability, particularly of poorly soluble and/or poorly permeable compounds and those that are extensively […]

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The Simcyp Population-based ADME Simulator

The Simcyp® population-based absorption, distribution, metabolism and excretion simulator is a platform and database for ‘bottom-up’ mechanistic modelling and simulation of the processes of oral absorption, tissue distribution, metabolism and excretion of drugs and drug candidates in healthy and disease populations. It combines experimental data generated routinely during preclinical drug discovery and development from in […]

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Development of CYP2D6 and CYP3A4 in the First Year of Life

Recently, Blake et al . ‘‘Ontogeny of dextromethorphan O- and N-demethylation in the first year of life’’ reported that CYP2D6 activity does not change with post-natal age up to 1 year. However, this conclusion, which was based on an invariant urinary dextromethorphan/dextrorphan (DM/DX) ratio over this period, is inconsistent with findings from studies in which […]

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