The drug conc-time profile in the effect compartment can be determined by : Pharmacokinetic/pharmacodynamic modeling (Cond't)

Pharmacokinetic/pharmacodynamic
modeling using an effect compartment
(Cond't)

The Effect Compartment

Effect compartment

k 1e

k e0

Plasma

k

The drug conc-time profile in plasma can be described by :

Cp=

Dose

Vd e -kt

The drug conc-time profile in the effect compartment can be determined by :

Ce=

D ke0

Vd(ke0 - k) (e -kt - e -ke0 t)

If we assume that the drug conc-effect relationship follows the Emax model, then :

E =

Emax Ce

EC50 + Ce

1- The drug plasma conc-time data are used to determine the pharmacokinetic parameters (k and V).

2- The kinetic parameters are substituted into the equation for the drug profile in the effect compartment. The drug conc in the effect compartment is substituted in the Emax model equation.

3- The effect observations are used to estimate the pharmacodynamic parameters Emax EC50 and ke0.

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