FIG. 2.

Structural models for pharmacokinetic analysis. Model equations are as follows.  

 

For linear models:

 

For nonlinear models:

 

D, dose; F, bioavailability; K_a, absorption rate constant; R(1), rate of infusion into central compartment; T_i, infusion time; V_s, volume of central compartment normalized to body weight; K₂₃, rate constant from central to peripheral compartment; K₃₂, rate constant from peripheral to central compartment. For nondistributive models, K₂₃ and K₃₂ were fixed at 0.0. Nonlinear elimination: V_max, maximum velocity; K_m, Michaelis-Menten constant; linear elimination, K₂₀ (elimination rate constant).