How TB-500 works
A short piece of thymosin beta-4 with no proven repair benefit in humans.
Also called: TB500, Ac-LKKTETQ, Thymosin beta-4 fragment 17–23.
Healing and repair peptides · N-acetylated seven-amino-acid thymosin beta-4 fragment.
It copies a short region of thymosin beta-4 involved in cell movement. Results for full-length Tβ4 or the unacetylated fragment cannot be assumed to apply to Ac-LKKTETQ. A lab study found wound-closure activity in one breakdown product, rather than the parent fragment.
- Actin-binding region, residues 17–23: Related to cell movement in lab models; the acetylated fragment has not shown a clear human effect.
- Ac-LKKTE metabolite: Improved fibroblast wound closure in a lab assay; this was not a human wound trial.
Half-life: Human half-life is unknown. Claims of a multi-day half-life are not established by human PK studies.
Related to TB-500
- BPC-157: An experimental repair peptide with mostly animal evidence and a few small human reports.
- GHK-Cu: A copper-binding skin peptide with small topical studies and untested systemic injections.
- AHK-Cu: A copper peptide used in scalp serums, with laboratory findings and weak patent-only human data.
- Thymosin beta-4: A peptide studied for eye conditions and skin wounds; tendon-repair injections lack controlled human evidence.
- ARA-290: Experimental peptide studied for small-fiber nerve damage, with uncertain pain relief and safety.
- Ac-SDKP: An experimental repair peptide with old human studies, but no proven healing dose.
Sources
- 503B Bulk Drug Substances List, FDA · FDA · 2026
- Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act, FDA · FDA · 2026
- Cellulitis, NHS · NHS · 2026
- Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks, FDA · FDA · 2026
- Federal Register: nonbinding draft HHS interim policy, October 30 2026, 2026
- HHS 503A peptide interim enforcement policy and conditions, October 30 2026, 2026
- July 23-24, 2026, Meeting of the Pharmacy Compounding Advisory Committee – FDA Briefing Document for TB-500-Related Bulk Drug Substances (TB-500 (free base) and TB-500 acetate), FDA · FDA · 2026
- July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee - 07/23/2026, FDA · FDA · 2026
- Medicines, European Medicines Agency · European Medicines Agency · 2026
- MHRA Products | Home, MHRA · MHRA · 2026
- The 2026 Prohibited List, World Anti-Doping Agency · WADA · 2026
- Therapeutic Goods (Poisons Standard—October 2026) Instrument 2026, Australian Government · Australian Government · 2026
- Think twice before injecting peptides bought online: unauthorized products can seriously harm you, Health Canada · Health Canada · 2026
- Thymosin Beta-4, Sport Integrity Australia · 2026
- Anaphylaxis, NHS · NHS · 2023
Sources checked: 2026-10-18.
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