KINFIT: a non linear least-squares computer program for the estimation of pharmacokinetic parameters after intravenous administration.

KINFIT is a nonlinear least-squares computer program designed to allow pharmacokinetic modeling of experimental data and to obtain pertinent parameter estimates based on the derived values. It is written in Visual BASIC for the Microsoft Windows graphical environment. Drug concentrations in blood, plasma, or serum with time following intravenous administration are input and a linear or semi-logarithmic plot of the data appears on the display. On command, polyexponential coefficients and exponents are computed and a non linear curve is fitted through the data set. Results from statistical tests are printed to determine goodness of fit. Commonly calculated pharmacokinetic parameters are also calculated and appear on the output. The execution of KINFIT is demonstrated for time courses of ampicillin in man. KINFIT was compared with the widely available ESTRIP and RSTRIP computer programs and gave parameter estimates that were very similar, although not identical.