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Delayed Effect and Effector Turnover

Most of the ICP modules relate dose to plasma drug concentration. However, in practice, the relationship between dose and drug effect is more important to the patient and healthcare provider. All drugs have a delay of effect in relation to plasma concentration. For some drugs the delay in effect is because the drug induces or inhibits turnover of an effector molecule. The elimination of the effector molecule determines rate of turnover and the delay in effect. An example is warfarin (Cp - blue line), prothrombin complex activity (effector molecule- green line) and INR (anticoagulant effect – red line).

Move the slider to see the relationships between Cp and drug effect with different elimination half-lives of the effector molecule.

Cp (mg/L)

Effector Molecule



Time (hrs)

Rapid Slow