CC13 – Volume of distribution

CC13. Volume of distribution is an indication of the extent to which a drug is distributed to the tissues of the body and is defined as the theoretical volume needed to dilute the total amount of drug in the body at a given time to achieve the measured plasma concentration.

13.1. Drugs with large volumes of distribution are extensively distributed throughout the tissues of the body, while drugs with a small volume of distribution are more restricted to the plasma.

13.2. The volume of distribution can be affected by physicochemical factors of the drug (e.g., lipophilicity and protein binding), patient factors (e.g., body fat content and plasma protein levels) and tissue-specific factors (e.g., tissue blood flow and permeability).

13.3. The volume of distribution is related to elimination half-life: Given similar clearances, drugs with a small volume of distribution tend to have a relatively short half-life; large volumes of distribution tend to indicate prolonged half-life due to the reservoir effect of tissue distribution.