Physiologically Based Structure of Mean Residence Time

Figure 1

Circulatory model of the system 𝐻_𝑖𝑣 describing drug disposition in a human body after an intravenous bolus dose of a drug. The drug administration is denoted by 𝐼_𝑖𝑣. The concentration-time profile of the drug in arterial blood denoted with 𝐶_𝐴. The concentration-time profile of the drug in venous blood denoted with 𝐶_𝑉. The cardiopulmonary subsystem, describing the drug transport through the heart and lungs, is denoted by 𝐻_𝑐𝑝.𝐻_𝑝 is the portal-venous subsystem describing the portal transport of the drug. 𝐻_ℎ is the hepatic-portal subsystem describing the hepatic transport of the drug. 𝐻_𝑜 is the subsystem describing the drug transport through noneliminating tissues. 𝐻_𝑟 is the subsystem describing the enterohepatic cycling. The subsystem 𝐻_𝑟 is shown by a dotted line, to indicate that the enterohepatic cycling is not always present. The symbol ⊗ denotes a summation operator. 𝑄_𝑐𝑝,𝑄_𝑝,𝑄_ℎ,𝑄_𝑜 are blood flows in the subsystems specified by the subscripts.