Pharmacodynamic Models: Overview

Pharmacodynamic or PD responses describe drug-target interactions and their biological effects.

PD models define the drug concentration–effect relationship, aiding efficacy prediction, dose optimization, and safety assessment.

Key components include drug–target binding, biophase distribution, biosignal transduction, and response generation. While biophase concentration influences the observed response, other factors also play a role.

PD models fall into three categories empirical models, which use mathematical descriptions; semi-mechanistic models, which incorporate partial physiological integration; and mechanistic models, which explicitly describe biological interactions.

PK–PD models integrate pharmacokinetics and pharmacodynamics to optimize therapy and reduce toxicity.

The E_max model describes effect saturation, while the Hill coefficient affects response steepness.

In anti-infective therapy, PK–PD indices—like C_max/MIC, AUC₂₄/MIC, and T > MIC—help optimize microbial killing and dose selection.