Simulating A Single Individual

In the first of several “how-to” style guides, we present some of the more fundamental concepts in pharmacokinetics and pharmacodynamics, using PoPy scripts to simulate data and figures to support our explanations. For ease of introduction, we consider only a single individual and look at populations of individuals in following parts (e.g. Simulating A Population Of Individuals).

Pharmacokinetics ([MouldUpton2012], [MouldUpton2013], [UptonMould2013], [RowlandTozer2012]) is the study of the time profile of drugs and metabolites in a physiological organism, often described as “what the body does to the drug”.

Typically, our goal is to build (or grow) a mathematical model that predicts a time course of drug concentration resembling the observations we have collected from an individual.

Pharmacodynamics, in contrast, describes “what the drug does to the body” and typically requires us to build a mathematical model that predicts a time course of biomarker concentration resembling the observations we have collected from an individual.

Often, the two are combined in a single model because the biomarker predictions are dependent (either directly or indirectly) on the drug predictions.

In this part, we consider factors of our mathematical model such as how drug is administered, distributed and eliminated, and also any errors in the way we observe PK/PD concentrations.

We assume little prior knowledge of PK/PD, and experienced modellers may be tempted to skip this section. It is, however, a gentle introduction to the syntax of PoPy models and how they are grown, bit by bit.