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:::::::{V_{D}} = rac{\mathrm{total \ amount \ of \ drug \ in \ the \ body}}{\mathrm{drug \ blood \ concentration}}

Therefore the dose required to give a certain plasma concentration can be determined if the VD for that drug is known. The VD is not a real volume; it is more a reflection of how a drug will distribute throughout the body depending on several physicochemical properties, e.g. solubility, charge, size, etc. The VD may also be used to determine how readily a drug will displace into the body tissue compartments relative to the blood:

:::::::{V_{D}} = {V_{P}} + {V_{T}} \left( rac{fu}{fu_{t}} ight)

Where:

VP = plasma volume

VT = apparent tissue volume

fu = fraction unbound in plasma

fuT = fraction unbound in tissue

Some examples:

Warfarin VD = 8L Reflects a high degree of plasma protein binding.

Theophylline , ''' Ethanol ''', VD = 30L Represents distribution in total body water.

Chloroquine VD = 15000L Shows highly lipophilic molecules which sequester into total body fat.