Tissue compartment

In a simple two-compartment model for drug disposition, the tissue compartment refers to all tissues and organs in the body into which drug may distribute that are not part of the central compartment (sometimes referred to as the plasma compartment, but which can also include some highly-vascularised organs). More complex models (e.g. a three-compartment model) may sub-divide the tissue compartment up into two compartments, for poorly-perfused tissues and for moderately-perfused tissues.

Drugs that partition extensively into the tissue compartment will leave a low concentration of drug in the plasma (central compartment) and this means the drug will usually have a high apparent volume of distribution.

Very rapid drug movement between the central compartment and the tissue compartment, or slower but very limited distribution from the central compartment, results in one-compartment kinetics, while slower movement of a significant portion of the dose administered will result in two-compartment kinetics, or in behaviour better described by a more complex model.