Publisher Summary
This chapter discusses various aspects of population pharmacokinetics (PK). PK studies in patients have led to the appreciation of the large degree of variability in PK parameter estimates that exists across patients. Population PK parameters quantify population mean kinetics, between-subject variability (intersubject variability), and residual variability. Residual variability includes within-subject variability, model misspecification, and measurement error. The structural kinetic models used when performing a population analysis do not differ at all from those used for analysis of data from an individual patient. The chapter describes nonlinear mixed-effects method using the conventions of the NONMEM software. Each individual PK parameter can be expressed as a population mean and a deviation—typical for an individual. The deviation is the difference between the population mean and the individual parameter and is assumed to be a random variable with an expected mean of zero and variance. The nonlinear mixed-effect analysis avoids many of these deficiencies and provides a flexible means of estimating population PK parameters.