kompartimentmodeller

Kompartimentmodeller, or compartment models, are mathematical frameworks used to describe how substances distribute and eliminate themselves within a system over time. They simplify complex biology or environments by dividing the space into discrete, well-mixed compartments that are connected by transfer pathways. Each compartment is characterized by its volume and by rate constants that govern movement between compartments and removal from the system. The simplest version is a one-compartment model, where the entire system behaves as a single, homogeneous compartment. More realistic descriptions use two or more compartments (for example, central and peripheral tissues), with first-order transfer between compartments and first- or zero-order elimination.

The dynamics are usually expressed as ordinary differential equations that track the amount or concentration in each compartment. Parameters include volumes of distribution, inter-compartment rate constants (such as k12, k21, k10 in pharmacokinetics), and absorption or dosing inputs. The models are fitted to experimental data to describe concentration–time profiles, tissue distribution, or exposure in pharmacokinetics, toxicology, or environmental science. They provide a compact, interpretable way to simulate how interventions or dosing schedules affect system behavior.

Variants and extensions include physiologically based pharmacokinetic (PBPK) models, which assign compartments to real organs and use blood flow to link them; nonlinear or saturable processes; and delay compartments that introduce time lags.

While useful, compartment models rely on simplifying assumptions such as instantaneous mixing within compartments and linear transfer kinetics, and they may suffer identifiability issues or poor predictive power when data are sparse or physiology changes over time.