Pharmacodynamic (PD) refers to what a drug does to the body, including its biological effects, mechanism of action, and relationship between exposure and response.
PD endpoints can include biomarkers, receptor occupancy, physiological changes, or clinical outcome measures that demonstrate pharmacologic activity. PD data are especially important in early-phase studies to support proof of mechanism and guide dose selection. When combined with safety and PK data, PD helps define therapeutic windows and dosing rationale. Clear PD measurement plans strengthen scientific interpretation and regulatory credibility.