TB-500

Classification

Actin-sequestering peptide fragment (research only)

Approval status

Research only · Not approved for human use

Research status

Research fragment / investigational. Thymosin beta-4 itself has been explored clinically in other formulations; TB-500 street products are not those medicines.

Molecular formula

Insufficient reliable evidence identified.

Molecular weight

Insufficient reliable evidence identified.

Sequence

Often sold as an acetylated fragment related to thymosin beta-4 (Tβ4); commercial ‘TB-500’ is not a single well-controlled pharmaceutical substance.

Primary biological target

Proposed actin-binding / cell-migration pathways of thymosin beta-4. Mechanism not yet fully established for grey-market fragments.

Half-life

Insufficient reliable evidence identified for standardised human PK of research-chemical TB-500.

Routes investigated

Parenteral in animal models of Tβ4; grey-market subcutaneous reports are not trials

Human evidence level

D — Primarily animal / preclinical evidence

A research-only peptide associated with thymosin beta-4 biology. Full-length Tβ4 has been explored pharmaceutically; consumer ‘TB-500’ is not an approved medicine.

Name used in research-chemical markets for Tβ4-related peptides. Endogenous Tβ4 is an actin-sequestering peptide.

Mechanism not yet fully established.

Proposed mechanism: thymosin beta-4 binds G-actin and has been studied in cell migration and repair models. Mechanism not yet fully established for uncharacterised TB-500 vials. Do not equate a vendor label with pharmaceutical Tβ4.

Not established for marketed research chemicals.

• Tissue-repair models

  D · Primarily animal / preclinical evidence

  Preclinical studies suggest roles for Tβ4 in wound and cardiac models. Human grey-market TB-500 use is not that evidence base.^[1]

Investigational findings are not proven clinical benefits unless an authority has labelled that indication.

Overall human evidence grade: D · Primarily animal / preclinical evidence

Pharmaceutical Tβ4 programmes have been limited; TB-500 vials sold online are not those programmes.

Animal, cell and in-vitro findings are listed separately from human effects.

• Animal experimental: Animal wound / cardiac injury models of thymosin beta-4

  Preclinical studies suggest repair-related signals. Not a human sports-medicine indication.

  Limitations: Fragment identity of commercial TB-500 is often unverified.

  ^[1]

This section does not provide personalised medical dosing. Values are those reported in papers or protocols. Animal mg/kg doses are not converted to human doses.

Doses reported in human studies

Insufficient reliable evidence identified.

Preclinical / animal study dosing

Insufficient reliable evidence identified.

Reliable human PK for research-chemical TB-500 were not identified.

Insufficient reliable evidence identified for a labelled AE profile.

Unknowns. Misidentification and contamination are practical risks of unregulated peptides.

Contraindications. Not for human use. Prohibited in sport.

Australia — TGA

Not approved as TB-500. Not sold here.

United States — FDA

Not approved as a TB-500 drug.

European Union — EMA

Not approved.

1. [1] Thymosin β4: a multi-functional regenerative peptide

   Goldstein AL et al. Thymosin β4: a multi-functional regenerative peptide Expert Opin Biol Ther. 2012. PMID 22646022

   PMID 22646022