Volume of distribution
THEORETICAL VOLUME THAT WOULD BE NECESSARY TO CONTAIN THE TOTAL AMOUNT OF AN ADMINISTERED DRUG AT THE SAME CONCENTRATION THAT IT IS OBSERVED IN THE BLOOD PLASMA.
Distribution volume; Apparent volume of distribution
In pharmacology, the volume of distribution (VD, also known as apparent volume of distribution, literally, volume of dilution) is the theoretical volume that would be necessary to contain the total amount of an administered drug at the same concentration that it is observed in the blood plasma. In other words, it is the ratio of amount of drug in a body (dose) to concentration of the drug that is measured in blood, plasma, and un-bound in interstitial fluid.