Volume of distribution of drug is given by

Apparent volume of distribution (Vd); Presuming that the body behaves as a single homogeneous compament with volume V into which drug gets immediately and uniformly distributedvd =dose administered i.v./ plasma concentration volume of distribution 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. Ref -KD Tripathi Pharmacology 7th edition (page no;17)