PK/PD models
A PK/PD model connects the concentration over time to a pharmacological response.
A PK/PD model connects the concentration over time to a pharmacological response (FDA. Exposure–Response Relationships: Study Design, Data Analysis, and Regulatory Applications. 2003.).
A direct Emax model assigns the same effect to the same concentration. If concentration peaks at hour 1 but a biomarker peaks at hour 6, serial measurements can help distinguish a delay in drug equilibration from slow biomarker turnover. Both can produce a delay, so its presence alone does not identify the mechanism.