7.12 : Two-Compartment Open Model: Overview

Multicompartmental models are crucial tools in pharmacokinetics, providing a framework to understand how drugs move within the body. The two-compartment model is a crucial subtype, segmenting the body into central and peripheral compartments. The central compartment represents areas with high blood flow, such as plasma and highly perfused organs like the kidneys and liver, while the peripheral compartment signifies tissues with lower blood flow, like adipose tissue and muscle tissue.

The assignment of tissues to either compartment depends on their level of perfusion. For instance, plasma is a central compartment due to its high perfusion, whereas adipose tissue, with lower perfusion, falls into the peripheral category.

In these models, drug concentration drops swiftly in the central compartment post-administration, owing to the drug's rapid distribution to the peripheral compartment. This is followed by a slower decrease in concentration in the peripheral compartment as the drug is gradually eliminated from the body.

Two-compartment models can be further categorized depending on the elimination kinetics. For instance, models with first-order elimination kinetics are called two-compartment open models, while those with zero-order elimination kinetics are called two-compartment closed models. These models provide valuable insights into the body's complex drug distribution and elimination processes.