A dispersion model of hepatic elimination: 2. Steady-state considerations--influence of hepatic blood flow, binding within blood, and hepatocellular enzyme activity.

The dispersion model of hepatic elimination is based on the distribution of residence times of blood elements within the liver. The model has two asymptotic solutions corresponding to the "well-stirred" model (complete mixing of blood elements) and the "parallel-tube" model (no variation in residence times of blood elements). The steady-state form of the dispersion model relevant to pharmacokinetic analysis is developed and explored with respect to changes in blood flow, in binding within blood, and in hepatocellular enzyme activity. Literature data are used to evaluate discrepancies among the predictions of the dispersion, well-stirred, and tube models. It is concluded that the dispersion model is consistent with the data. The limitations of steady-state perfusion experiments to estimate the residence time distribution of blood elements within the liver are considered.