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## The Difference Between Vd and Vss

There are many terms used to represent volume of distribution, but two common ones are Vd and Vss. Vd is the apparent volume of distribution. It can be calculated using the following equation:

$Vd=\frac{F*D}{AUC_{0-t}*k_{el}}$

Vss is the apparent volume of distribution at steady state. Or, the sum of all volume terms in a multicompartment model. It can be calculated using the following equation:

$Vss=\frac{D*AUMC_{infty}}{AUC_{infty}^2}$

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