Figure 1. Flow-limited two-subcompartment and well-stirred PBPK tissue compartment model diagrams.

A) Flow-limited two-subcompartment (FLT) model, Eq.17; and B) well-stirred tank (WST) model, Eq.5. The flow-limited two-subcompartment model has both vascular (V1) and extravascular (V2) spaces and simulates total concentration in the compartment, cT, as a function of the volume and concentrations in each subcompartment. The outflow concentration differs between the flow-limited two-subcompartment and well-stirred tank models depending on the type of partition coefficient used (λbiophys or λwell-stirred) and the fractional blood volume (FBV) of the compartment. The flow-limited two-subcompartment model is a general flow-limited case of the PLT model. The well-stirred tank model is a specific flow-limited case of the PLT model where FBV → 0.