TB-500
Synthetic peptide fragment · Related to thymosin beta-4, often conflated with it
- UK status
- Unlicensed medicine
- Availability
- Research use only
- Evidence base
- Animal studies, no human trials
- Controlled drug
- No, but WADA prohibited
Peptide sequence, one-letter notation
LKKTETQ
TB-500 is usually described as thymosin beta-4. It is not quite. It is a short fragment of that protein, and the distinction matters when you go looking for the research behind the claims.
01What it is
Thymosin beta-4 is a naturally occurring protein of 43 amino acids involved in cell movement and tissue repair. TB-500 is a synthetic fragment of it, a much shorter sequence containing the region thought to carry the actin-binding activity.
Marketing material tends to use the two names interchangeably. Research on the full protein is then presented as though it applies to the fragment being sold. Sometimes it may. It is not automatic, and it is worth checking which one any given study actually used.
02UK legal and licensing status
Unlicensed in the UK, with no MHRA authorisation for human use. Not a controlled drug, but supply for human use without authorisation is prohibited. Sold as a research chemical labelled not for human consumption.
Athletes: prohibited by WADA at all times. Thymosin beta-4 and its fragments fall within the prohibited classes, and as with BPC-157 strict liability applies.
03How it works
The proposed mechanism involves binding actin, a protein central to how cells move, and thereby influencing cell migration into damaged tissue and the formation of new blood vessels. This is derived from laboratory and animal work on thymosin beta-4.
04What the evidence shows
Animal and laboratory studies report effects on wound healing and tissue repair. Human clinical trial evidence for TB-500 as sold does not exist in any meaningful form. Some clinical work has been done on thymosin beta-4 preparations for specific indications, which is a different compound in a different context from a vial bought online.
No human safety data, no standardised product, no long-term follow-up. The same asymmetry as BPC-157: the unknowns are larger than the knowns.
05Reported harms
No regulated safety profile exists. The risks that can be stated with confidence are those of unregulated supply: unverified identity and purity, non-sterile handling, and no route to redress.
06Sources
Links go to the primary source. Where a source is behind a paywall or requires registration, the citation is given so you can find it yourself.
- Unlicensed medicines guidanceMHRA
- Prohibited ListWADA
- Thymosin beta-4 and tissue repair, review literaturePubMed
07Change history
Every substantive change to this record is logged here with its date. Corrections are made openly, not quietly.
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