3. Importance of Pharmacokinetics (PK) and Pharmacodynamics (PD)

  • Pharmacokinetics (PK) study what the body does to the medicine. This means they:
    • Determine the plasma time-concentrations (active substance, metabolites).
    • Establish the exposures that have an effect in vivo (Latin for ‘in the living’).
    • Allow systematic exposure in order to assess toxicology

  • Pharmacodynamics (PD) study what the medicine does to the body. This means they:
    • Provide measures of on-target medicine effect and duration of effect.
    • Assay depends on mechanism of action.

PK and PD influence how the dose is selected and they help schedule how it is used.