Abstract
Pharmacokinetic analysis of arithmetic mean concentration data can lead to selection of an inappropriate deterministic compartmental model and biased pharmacokinetic parameter estimates. The terminal phase disposition rate constant estimated by fitting a deterministic model to mean data is in all cases an underestimate of the expected value of this rate constant. The area under the mean data curve calculated via the linear trapezoidal rule from time zero to the last detectable concentration sampling point is equal to the mean of the individual subject areas under the curve for the same time span. This equality supports the use of mean data for determination of model-independent pharmacokinetic parameters.
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Abbreviations
- AUC ∞Oi :
-
total area under the curve for theith subject
- AUC ∞Oari :
-
total area under theC ari versus time curve
- \(\overline {AUC} _0^\infty \) :
-
arithmetic mean of the total area under the individual subject's concentration versus time curve=
$$ = \frac{1}{n}\sum\limits_{i = 1}^n {AUC_{0_i }^\infty } $$ - AUC ∞Oln :
-
total area under theC ln versus time curve
- C ari :
-
arithmetic mean concentration
- C O :
-
concentration at time zero
- \(\bar C\) o :
-
arithmetic mean of the individual subject'sC O values
- C Oari :
-
concentration at time zero extrapolated from theC ari versus time curve
- C ln :
-
arithmetic mean of the logarithmic values of individual subject concentrations
- \(\bar C\) ss :
-
average steady-state concentration
- K i :
-
first-order elimination rate constant for theih subject
- K ari :
-
arithmetic mean elimination rate constant
- K har :
-
harmonic mean elimination rate constant
- n :
-
number of subjects
- V i :
-
apparent volume of distribution for theith subject
- V geom :
-
geometric mean apparent volume of distribution
- V har :
-
harmonic mean apparent volume of distribution
- X O :
-
i.v. bolus dose
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Cocchetto, D.M., Wargin, W.A. & Crow, J.W. Pitfalls and valid approaches to pharmacokinetic analysis of mean concentration data following intravenous administration. Journal of Pharmacokinetics and Biopharmaceutics 8, 539–552 (1980). https://doi.org/10.1007/BF01060052
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DOI: https://doi.org/10.1007/BF01060052