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Significance of ratios of different volumes of distribution in pharmacokinetics
Author(s) -
Wagner John G.
Publication year - 1983
Publication title -
biopharmaceutics and drug disposition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.419
H-Index - 58
eISSN - 1099-081X
pISSN - 0142-2782
DOI - 10.1002/bdd.2510040307
Subject(s) - volume of distribution , distribution (mathematics) , chemistry , pharmacokinetics , compartment (ship) , volume (thermodynamics) , beta (programming language) , distribution volume , thermodynamics , mathematics , medicine , physics , mathematical analysis , geology , oceanography , computer science , programming language
Multicompartmental pharmacokinetics involves the four volumes: V c = volume of the central compartment; V ss = volume of distribution steady‐state; V β = volume of distribution beta; and V ext = the extrapolated volume of distribution. The ratio V c / V ext is indicative of the degree of multicompartmental character of a set of data. The quantity ( V ext / V β )−1 is the fractional error in the total clearance when one assumes a monoexponential rather than a polyexponential equation for disposition of a drug. The ratio V ss / V β indicates how well the one‐compartment body model predicts average amounts of drug in the body when a multicompartmental model is actually operative. The quantity ( V ss / V c )− 1 is equal to either k 12 / k 21 or k 12 / k 21 + k 13 / k 31 of the two‐ and three‐compartmental mammillary models. Examples from the literature are reported and discussed.