Preclinical:
Laboratory & animal models
Goal: Explore if & how new treatment may work
Phase I:
Small number (eg, 20-100) of healthy subjects
Goal: Evaluate toxicity, maximum tolerated dose, adverse effects, pharmacokinetics & pharmacodynamics of new treatment (safety)
Phase II:
Small number (eg, up to a few hundred) of affected subjects
Goal: Explore efficacy, optimal dosing & adverse effects of new treatment (expanded safety)
Phase III:
Large number (eg, 300-3,000) of affected subjects randomly assigned to new treatment or control
Goal: Compare new treatment to current standard of care (safety & efficacy)
Phase IV:
Postmarketing surveillance
Goal: Identify rare & long-term adverse effects