Phases

Phase No. patients Duration Location Purpose

I 20–80
(healthy) 36 hours, over 2–6 weekends Single site Bioavailability, pharmacokinetics, safety, dosing regimens/ranges


II 50–200
(diseased) 36 hours, over 1–4 weekends Single site Safety and preliminary efficacy

III 100–2000
(diseased) 6 months–
3 years 30–40 sites Immediate and long-term safety and efficacy

IVa 100–2000
(diseased) 6 months–
3 years 30–40 sites Efficacy for alternate indications