What do k12, k21, and k10 represent in the two-compartment model?

What do k12, k21, and k10 represent in the two-compartment model?

• A. K12 is the rate constant for transfer from peripheral to central, K21 from central to peripheral, and K10 for elimination from the central compartment.
• B. K12 is the rate constant for elimination from the central compartment; K21 for central to peripheral; K10 for peripheral to central.
• C. K12 is the rate constant for transfer from central to peripheral, K21 from peripheral to central, and K10 for elimination from the central compartment.
• D. K12 is the rate constant for transfer from central to peripheral; K21 for elimination from central; K10 for transfer from peripheral to central.

Answer: (C)

In a two-compartment pharmacokinetic model, the body is divided into a central compartment and a peripheral compartment. The rate constants describe how fast the drug moves between compartments and how fast it’s eliminated. k12 is the rate constant for transfer from the central to the peripheral compartment, k21 is the rate constant for transfer from the peripheral back to the central compartment, and k10 is the rate constant for elimination from the central compartment. This setup is reflected in the usual differential equations: the central amount changes by losing to the peripheral and by elimination, while gaining from the peripheral, and the peripheral amount changes by the transfer from central and by returning to central. Because elimination occurs from the central compartment, and distribution between central and peripheral is described by the two intercompartmental constants, the stated definitions match the standard model.

In a two-compartment pharmacokinetic model, the body is divided into a central compartment and a peripheral compartment. The rate constants describe how fast the drug moves between compartments and how fast it’s eliminated. k12 is the rate constant for transfer from the central to the peripheral compartment, k21 is the rate constant for transfer from the peripheral back to the central compartment, and k10 is the rate constant for elimination from the central compartment. This setup is reflected in the usual differential equations: the central amount changes by losing to the peripheral and by elimination, while gaining from the peripheral, and the peripheral amount changes by the transfer from central and by returning to central. Because elimination occurs from the central compartment, and distribution between central and peripheral is described by the two intercompartmental constants, the stated definitions match the standard model.