PK/PD Modeling & Simulation

Relationship Between AUC and Volume of Distribution

Nathan Teuscher

A few days ago on the pharmacokinetics listserve PharmPK, the following question appeared: I’m having trouble wrapping my head around this question from an online pharmacology quiz.  The question is “The larger the volume of distribution, the smaller the AUC of a given drug.”  The answer is given as “False.” As I look at the […]

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Topics: PK/PD Modeling & Simulation

Where Did the 80-125% Bioequivalence Criteria Come From?

Nathan Teuscher

Most people involved in clinical pharmacokinetics are familiar with the 80-125% criterion. This criterion is used to compare two treatments with the purpose of evaluating if the treatments are bioequivalent. But, where did this come from? Why 80-125%? Why not 90-110%? or why not 80-120%? Before we explain where 80-125% came from, let me explain […]

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Topics: PK/PD Modeling & Simulation

Deciding on Which Drug-drug Interactions to Evaluate in the Clinic

Nathan Teuscher

Drug-drug interactions are a critical research area in pharmaceutical drug development. One of the most tragic examples of drug-drug interactions was the antihistamine terfenadine. Terfenadine (also known as Seldane) was a common antihistamine intended to block the effects of an allergic rhinitis. Upon administration terfenadine is metabolized to fexofenadine by the cytochrome P450 3A4 isoform. […]

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Topics: PK/PD Modeling & Simulation

What are Compartmental Models?

Nathan Teuscher

Almost everyone familiar with pharmaceuticals has heard a conversation like this before: Scientist 1: “What are the pharmacokinetics of Drug X?” Scientist 2: “Drug X follows a 1-compartment model in rats, but in monkeys it tends to have a distribution phase and seems to follow 2-compartment kinetics.” Scientist 1: Thinks to himself/herself …’What does a […]

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Topics: PK/PD Modeling & Simulation

What are Drug-drug Interactions Anyway?

Nathan Teuscher

A current buzz phrase in pharmaceutical research right now is “drug-drug interaction” or simply “drug interaction”. The definition of a drug-drug interaction has fluctuated over the last few years, not because of changes in research, but because of misconceptions in the research community. The US Food and Drug Administration (FDA) has published a draft guidance […]

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Topics: PK/PD Modeling & Simulation

Trial Designs—Non-inferiority vs. Superiority vs. Equivalence

Nathan Teuscher

The primary purpose of a clinical trial is to address a scientific hypothesis. To address a hypothesis, different statistical methods are used depending on the type of question to be answered. Most often the hypothesis is related to the effect of one treatment as compared to another. For example, one trial could compare the effectiveness […]

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Topics: Clinical Pharmacology Strategy
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