Central compartment

An alternative and preferable name for the plasma compartment. The central compartment is the compartment into which drugs are initially administered or absorbed, and the compartment from which drugs are generally eliminated. See also A+B Intercept. Note that the central compartment volume often includes tissues into which the drug distributes very rapidly (usually as a result of very lipophilic drugs distributing into highly-vascularised tissues such as liver, kidneys and/or brain), and it is not unusual for the central compartment volume to exceed the plasma volume.

When a drug behaves with one-compartment kinetics, all tissues and organs into which the drug of interest distributes extensively are considered to be part of the central compartment.

It can be useful to know the central compartment volume (sometimes referred to as AV_{D c}) for a drug, for several reasons. For example, a two- or multi-compartment drug’s target organ may be part of the central compartment, and a loading dose that considers only the rate at which equilibrium of drug between the central and tissue compartment(s) is reached, ignoring the peak concentration of drug in the central compartment (and thus in the target organ) could cause significant on-target side-effects or toxicity. Knowledge of the AV_{D c} facilitates administering the loading dose at a rate slow enough to avoid exceeding the maximum concentration that can be tolerated in the central compartment.