Some considerations on the estimation of steady state apparent volume of distribution and the relationships between volume terms.

Application of statistical moment theory to four methods which do not involve detailed compartmental analysis for the determination of Vss shows them to be equal. Assuming drug to be eliminated exclusively from the central compartment results in the minimum value of Vss being determined. A method for determining the maximum possible value of Vss is shown which uses AUC, dose (iv), and the exponents which describe the plasma-concentration time curve. The relationships between the volume terms Vextrap, Varea and Vss are discussed in terms of moment theory.