Two different molecules
Researchers analyzing products sold as TB-500 identified the active compound as the acetylated 17–23 fragment of thymosin beta-4. Other analyses found products labeled TB-500 whose contents did not match their descriptions. Always ask the pharmacy which molecule your prescription contains.
What the human trials of thymosin beta-4 tested
| Study | Design | Finding |
|---|---|---|
| Ruff et al., 2010 | Phase 1, randomized, placebo-controlled; 40 healthy volunteers; IV doses daily for 14 days | Well tolerated; no dose-limiting toxicity |
| Guarnera et al., 2010 | Phase 2, randomized, placebo-controlled; 73 people with venous leg ulcers; topical gel | Safety comparable to placebo; efficacy findings suggestive, not conclusive |
Neither study used the fragment or an injection under the skin. They are evidence about thymosin beta-4, not about TB-500.