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##### Asked by: Yunan Govoruhin

medical health pharmaceutical drugs# What does volume of distribution tell us?

Last Updated: 9th June, 2020

**volume of distribution**reflects the relationship between the amount of drug in the body at steady state and plasma drug concentration. The

**volume of distribution**is a mathematical concept, which

**does**not necessarily reflect a physiological or “real”

**distribution**space.

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Hereof, what is the significance of volume of distribution?

The **volume of distribution** (Vd) is a measurement of how a drug is dispersed in the body related to the measured plasma concentration. It's used to determine the loading dose of a drug, the half-life of a drug, medication clearance, and drug toxicity.

One may also ask, what does a low volume of distribution mean? **Definition**/Introduction Conversely, a drug with a **low** Vd has a propensity to remain in the plasma **meaning** a **lower** dose of a drug is required to achieve a given plasma concentration. (**Low** Vd -> Less **distribution** to other tissue)

In this regard, what does increased volume of distribution mean?

This **means** that most of the drug is in the tissue, and very little is in the plasma circulating. The larger the **volume of distribution**, the more likely that the drug is found in the tissues of the body. The smaller the **volume of distribution**, the more likely that the drug is confined to the circulatory system.

How does volume of distribution affect half life?

In brief : **Half**-**life** (t½) is the time required to reduce the concentration of a drug by **half**. The formula for **half**-**life** is (t½ = 0.693 × Vd /CL) renal failure with oedema) **volume of distribution** increases but clearance decreases, resulting in an unchanged **half life** (thus, it is a poor measure of drug clearance alone).