PK/PD modeling (pharmacokinetic/pharmacodynamic modeling) (alternatively abbreviated as PKPD or PK-PD modeling) is a technique that combines the two classical pharmacologic disciplines of

pharmacokinetics Pharmacokinetics (from Ancient Greek ''pharmakon'' "drug" and ''kinetikos'' "moving, putting in motion"; see chemical kinetics), sometimes abbreviated as PK, is a branch of pharmacology dedicated to determining the fate of substances administered ...

and

pharmacodynamics Pharmacodynamics (PD) is the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs). The effects can include those manifested within animals (including humans), microorganisms, or combinations of organisms ...

. It integrates a pharmacokinetic and a pharmacodynamic model component into one set of

mathematical expression In mathematics, an expression or mathematical expression is a finite combination of symbols that is well-formed according to rules that depend on the context. Mathematical symbols can designate numbers ( constants), variables, operations, f ...

s that allows the description of the time course of effect intensity in response to administration of a

drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via inhala ...

dose. PK/PD modeling is related to the field of

pharmacometrics Pharmacometrics is a field of study of the methodology and application of models for disease and pharmacological measurement. It uses mathematical models of biology, pharmacology, disease, and physiology to describe and quantify interactions between ...

. Central to PK/PD models is the concentration-effect or exposure-response relationship. A variety of PK/PD modeling approaches exist to describe exposure-response relationships. PK/PD relationships can be described by simple equations such as

linear model In statistics, the term linear model is used in different ways according to the context. The most common occurrence is in connection with regression models and the term is often taken as synonymous with linear regression model. However, the term ...

, Emax model or sigmoid Emax model. However, if a delay is observed between the drug administration and the drug effect, a temporal dissociation needs to be taken into account and more complex models exist: * Direct vs Indirect link PK/PD models * Direct vs Indirect response PK/PD models *Time variant vs time invariant * Cell lifespan models * Complex response models PK/PD modeling has its importance at each step of the drug development and it has shown its usefulness in many diseases. The

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

also provides guidances for Industry to recommend how exposure-response studies should be performed.

References

Pharmacodynamics Pharmacokinetics {{pharma-stub