Figure 2. The population pharmacokinetic-pharmacodynamic (PK-PD) models of warfarin.

Three models were employed to describe the time courses of the plasma concentration of S-warfarin, Cp(S) by the 1-compartment model (Eq.1) and normal prothrombin (NPT) by the indirect model (Eq.2) and the INR by the nonlinear model (Eq.3). Population parameters of CL(S) in PK, IC₅₀ and Kout in PD-1 and λ in PD-2 were estimated.