Volume of Distribution
Body Compartment Model
Volume of Distribution is considered in relation to body “compartments”.
Some highly polar drugs, such as penicillins, distribute mainly into “central” compartments and have a small Vd, while highly lipid soluble drugs, such as tricyclic antidepressants, distribute far more widely and have a large Vd.
Inject drug, and progressively add compartments to see what happens as the drug distributes more widely in the body.
You will see that Ab (Amount in body), Vd and Cp are clearly related.