WNL Classic Models

PD output parameters in a PK/PD model

The output parameters for PD models in a linked PK/PD model differ from the parameters for PD models that are not linked. The following table lists the PD model parameters used in linked PK/PD models.

PD model	Estimated parameters	Secondary parameters
101 Simple Emax model	Emax, EC₅₀, Ke0
102 Simple Emax model with a baseline effect	Emax, EC_50,E0, Ke0	Rmax, F_Emax
103 Inhibitory effect E0 model	E0, IC₅₀, Ke0
104 Inhibitory effect Imax model with a baseline effect	Imax, IC₅₀, E0, Ke0	Rmax, F_Emax
105 Sigmoid Emax model	Emax, EC₅₀, Gamma, Ke0
106 Sigmoid Emax model with a baseline effect	Emax, EC_e50, E0, Gamma, Ke0	Rmax, F_Emax
107 Inhibitory effect sigmoid E0 model	E0, IC₅₀, Gamma, Ke0
108 Inhibitory effect sigmoid Imax model with a baseline effect	Imax, IC₅₀, E0, Gamma, Ke0	Rmax, F_Emax

The table below lists definitions for the estimated and secondary parameters.

Term	Definition
Emax	Maximum drug effect.
Imax	Maximum drug inhibition.
EC₅₀	Concentration in plasma that achieves 50% of predicted maximum effect in an Emax model.
ECe₅₀	For effect compartment models, the concentration at the effect site that achieves 50% of predicted maximum effect in an Emax model.
IC₅₀	Drug concentration required to produce 50% of the maximal inhibition.
E₀	Baseline effect (effect at 0). In models 103 and 107, E0 could also be named Imax, the maximum drug inhibition.
Gamma	Shape parameter.
Ke0	Exit rate constant from effect compartment.
Rmax	Observed or predicted maximum response.
F_Emax	Fractional change in response from baseline E₀.