PBPK Modeling & Simulation

The Year in Review for Biosimulation and Regulatory Writing

Suzanne Minton

Happy New Year! 2015 was a year of huge growth— both personally and professionally— for our Certara® family. We’re so grateful for our clients who give us the privilege of supporting them in their work to bring safer and more effective treatments to patients. In this blog post, I’ll be looking back at the top 10 […]

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Topics: PBPK Modeling & Simulation, Regulatory & Medical Writing

Can Modeling & Simulation Inform Personalized Medicine?

Kevin Feng

Pharma faces an existential crisis. The cost and time lines of developing new medications have been growing exponentially for decades, with no end in sight. Could modeling and simulation approaches be the Next Great Hope for ending this madness and restoring sustainability to drug development? At the same time, can it deliver on the promise of […]

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Topics: PK/PD Modeling & Simulation

9 Frequently Misunderstood Concepts in PK/PD Modeling

Nathan Teuscher

In teaching pharmacometrics, I’ve noticed that scientists have difficulty with certain PK/PD modeling concepts. Maybe you’ve read about some of these terms in journal articles, but didn’t know what they meant? Or you’ve heard these terms bandied about by colleagues, but felt too shy to ask them what they meant? I’ll clarify some important concepts […]

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Topics: PK/PD Modeling & Simulation

9 Things Your Boss Wishes You Knew About PK/PD Modeling

Nathan Teuscher

Over the course of my career, I have taught the theory and practical applications of PK/PD modeling to hundreds of scientists. In this blog post, I’ll share some of my most popular tips for solving common difficulties encountered by pharmacometricians. The tools of the trade While I have worked with a number of pharmacometrics tools, I […]

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Topics: PK/PD Modeling & Simulation

Adding a Placebo Component to Your PK/PD Model in Phoenix

Nathan Teuscher

PK/PD modeling is an exciting are of research in clinical pharmacology. Most often we try to model the effect of a drug by drawing relationships between the concentration and effect. This usually entails subsetting the data to exclude information from subject that received placebo during the trial. But statistical comparisons in clinical studies are most […]

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Topics: PK/PD Modeling & Simulation

What is Identifiability?

Nathan Teuscher

Developing models for pharmacokinetic or pharmacodynamic data requires creativity, patience, and hard work. Sometimes that creativity ends up violating mathematical principles which can lead to poorly fitting models and frustration for a modeler. One common area where mistakes are made is related to the analysis of parent and metabolite data simultaneously. Because data are available […]

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Topics: PK/PD Modeling & Simulation

What is the -2LL or the Log-likelihood Ratio?

Nathan Teuscher

If you have ever read the literature on pharmacokinetic modeling and simulation, you are likely to have run across the phrase  “-2LL” or “log-likelihood ratio”. These are statistical terms that are used when comparing two possible models. In this post, I hope to explain with the log-likelihood ratio is, how to use it, and what […]

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Topics: PK/PD Modeling & Simulation

Phoenix NLME Software Review—Part 3

Nathan Teuscher

In this third and final post about by review of the Phoenix WinNonlin software, I review the newest feature of the software and provide overall thoughts. You can read about the Phoenix platform in Part 1 of my review, and the non-compartmental and single subject analysis in Part 2 of my review. With the exception […]

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Topics: PK/PD Modeling & Simulation

What is Shrinkage?

Nathan Teuscher

In 2007, Mats Karlsson and Radojka Savic published a perspective in Clinical Pharmacology & Therapeutics titled “Diagnosing Model Diagnostics.” In this article they examined the use of diagnostic plots to evaluate the adequacy of model fits for nonlinear mixed-effects analysis. Although there is a wealth of information in this article, the population PK analysis community […]

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Topics: PK/PD Modeling & Simulation

Is a Monte Carlo Simulation an Exotic Drink?

Nathan Teuscher

The term “Monte Carlo simulation” is often used in the modeling and simulation literature with PK/PD analysis. When I was first exposed to this term, I was thoroughly confused and thought that it was some exotic statistical method that required 3 PhDs and a few days to comprehend. Well, I was very wrong. A Monte […]

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Topics: PK/PD Modeling & Simulation

What is the Difference Between Individual and Population PK?

Nathan Teuscher

Pharmacokinetic analysis is often broken into two areas … “PK” and “population PK”. Sometimes the first term “PK” is also called “individual PK”. I’d like to demystify these two analysis methods in this post. In the analysis of biological samples, we have many different detection technologies, for example mass spectroscopy, UV spectroscopy, radiometric detection, and […]

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Topics: PK/PD Modeling & Simulation

What are Direct and Indirect Pharmacodynamic Models?

Nathan Teuscher

When constructing pharmacodynamic (PD) models, you will often encounter the adjectives “direct” and “indirect” describing the associated PD model. This terminology was very confusing to me when I was learning about PD modeling. Hopefully a brief explanation will help you. Let’s start with the direct PD model. In this type of model, the drug is […]

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Topics: PK/PD Modeling & Simulation

What is Modeling and Simulation?

Nathan Teuscher

I am currently attending a short conference on modeling and simulation in pediatric clinical pharmacology, and I noticed that many people in the conference don’t have a good grasp on what “Modeling and Simulation” means. I think most of them think that it is an extremely complicated mathematical concoction that is intended to keep everyone […]

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Topics: PK/PD Modeling & Simulation

What is Pharmacodynamics?

Nathan Teuscher

Starting with definitions is always helpful… so after defining pharmacokinetics, a definition for pharmacodynamics is in order. The definition of pharmacodynamics (PD) is much less controversial than the definition for pharmacokinetics. The word pharmacodynamics is from two Greek words (see wikipedia for more): pharmakon: Drug dynamikós : force or power Thus, pharmacodynamics is the study […]

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Topics: PK/PD Modeling & Simulation

What is Pharmacokinetics?

Nathan Teuscher

You might think this is a simple question, especially for an expert in pharmacokinetics. Well, this question is full of controversy with each scientist having their own opinion. I think this is because the definition of pharmacokinetics is simple, yet pharmacokinetics science is broad in scope. The word pharmacokinetics is from two greek words (see […]

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Topics: PK/PD Modeling & Simulation

Why Have a Blog About PK and PD?

Nathan Teuscher

Many blogs you will find on the internet are related to personal ventures, technology, or hobbies … all topics that are suited to the light-hearted fare that is common in the blogosphere. I believe that blogs can communicate knowledge in unique ways to a broad audience. Instead of developing a blog about my personal life, […]

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Topics: PK/PD Modeling & Simulation
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