Glossary

Phase 1, 2 and 3

In one lineThe stages of drug trials.

Definition

Phase 1 tests safety and blood levels in a few dozen people. Phase 2 looks for an effect and a dose in a few hundred. Phase 3 confirms it in hundreds to thousands, against a comparator, and is what regulators approve on. Retatrutide is in phase 3; most research-market peptides never entered phase 1.

Where it matters on LYO

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