Bioavailability Distribution Absorption and Transport. Volume of Distribution. The volume of distribution is given by the following equation: Therefore the dose required to give a certain plasma concentration can be determined if the V D for that drug is known.
Absorption and Transport
The volume of distribution is given by the following equation:
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 physiologic value; 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.
VD is often calculated per weight of body – it is not volume any more!
Stomach 1-3 up to 5 m2 0.5-20 h
Small Intestine 5-7 200 m2 2 h
Colon 7-8 up to 5 2 h – 1 week
Diazepam 100 0.5-2
Morphine 15-60 3-5
Pentobarbital 95 0.7-10
Tetrahydrocannabinol 6 9-11
VD Proportion of Drug in body water
Concentration in bulk
Diffusion Layer thickness