Drugs that follow one-compartment model are rapidly distributed to all tissues after iv administration. Although the drug conc in different tissues is different, the body behaves as one kinetically homogeneous compartment, e.g. a decrease of 50% in plasma conc is usually accompanied by 50% decrease in the conc in all tissues.
In the two-compartment model, the drug profile in the tissues that represent the central compartment is different from the drug profile in the tissues that represent the peripheral compartment.
The drug profiles in different tissues within each compartment will be parallel, however the drug conc in different tissues are usually different.
Two-compartment model
Liver
Plasma
Intestine
Here we assumed that the plasma, liver and
intestine are part of the central compartment
Two-compartment model
Brain
Fat
Kidney
Here we assumed that the brain, fat and
kidney are part of the peripheral
compartment
