Setting confidence intervals for drug concentrations from pharmacokinetic parameters.
OBJECTIVE
To describe and illustrate a convenient method of forecasting drug concentrations with confidence intervals (CIs) using the means and standard deviations of relevant pharmacokinetic parameters (e.g., clearance and volume of distribution).


METHODS
Using summary statistics from previously published reports, a Monte Carlo technique employing a SAS random number generator creates an arbitrarily large "sample" of each pharmacokinetic parameter. A related "sample" of drug concentrations is provided by inserting the parameters into the appropriate model. A point estimate of the mean drug concentration with a CI is calculated using standard statistical methods. Both the one- and two-compartment body models are illustrated using previous investigations of gentamicin and lidocaine, respectively.


RESULTS
One-compartment simulations describe CIs for gentamicin concentrations that vary widely depending on the source of the clearance and volume of distribution parameters. Lidocaine CIs using a two-compartment analysis indicate a range of concentrations quite different from the expected mean.


CONCLUSIONS
CIs provide a perspective of drug therapy that is considerably more informative than a simple point estimate of the mean concentration.
Inciardi
J F
JF
Department of Pharmacy Services, University of California, Davis Medical Center, Sacramento.
Willits
N H
NH
D016001:Confidence Intervals; D004358:Drug Therapy; D005544:Forecasting; D005839:Gentamicins / Q000493:pharmacokinetics; D006801:Humans; D008012:Lidocaine / Q000493:pharmacokinetics; D008954:Models, Biological; D010599:Pharmacokinetics
D005839:Gentamicins; D008012:Lidocaine