Evidence & research
Clinical trial phases
Also known as: phase 1 · phase 2 · phase 3 · phase i · phase ii · phase iii
The staged sequence of human testing: safety and dosing (I), preliminary efficacy (II), then large confirmatory trials (III).
In plain terms
Phase I asks whether a dose can be given safely, usually in a few dozen people. Phase II asks whether it plausibly works. Phase III is the large, randomised, controlled test that approval usually rests on.
Most failures happen in phase II and III — that is, after the promising early results that get quoted.
Sources
Educational reference only. Pepperz does not provide medical advice, diagnosis, treatment, prescribing guidance, or dosing recommendations.