# TB-500 in Australia: What the Research Actually Shows

TB-500 is a synthetic seven-amino-acid fragment of thymosin beta-4, and in Australia it is a Schedule 4 substance that also sits in Appendix D of the Poisons Standard. Published work on the fragment is preclinical: cell assays, aged mice and a rat tendon model. No completed human trial of TB-500 has been published, and the single trial-registry record that appears to be one is a worked example rather than a real study. Supplied for in vitro research purposes only.

- Source: https://www.australianresearchpeptides.au/articles/tb-500-research-and-legal-status-australia
- Reading time: 12 minute read
- Published: 2026-09-04
- Publisher: Australian Research Peptides

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In vitro research purposes only.

TB-500 is an unapproved experimental compound. No medicines regulator in any country has authorised it for any use in a person. What follows summarises published laboratory studies and public regulatory records, and nothing on this page is an amount, an interval, a protocol or a recommendation. Every vial this business sells is laboratory material and nothing else.

## What Is TB-500?

TB-500 is a laboratory-made chain of seven amino acids — Leu-Lys-Lys-Thr-Glu-Thr-Gln, usually written LKKTETQ — carrying an acetyl cap on one end. Those seven residues are copied from a much larger human protein called thymosin beta-4, which runs to 43 residues and which the literature describes as the most abundant member of the beta-thymosin family in mammalian tissue.

The identity of the material sold under the name is not guesswork. A 2012 analytical paper from a doping-control laboratory in Ghent put a TB-500 preparation through high-resolution mass spectrometry, found the acetylated 17-23 fragment inside it, and then made the same sequence from scratch to confirm the match. So what the name refers to is settled; what it does is the part that is not.

Where the parent protein sits relative to the fragment is set out at length in [BPC-157 vs TB-500](https://www.australianresearchpeptides.au/articles/bpc-157-vs-tb-500), which takes the two apart section by section. This page starts one step further on, from a question that guide does not ask: whether the published biology belongs to the molecule in the vial at all.

## Why Does the Acetyl Group Matter?

The acetyl group matters because most of the classic activity was reported for the uncapped sequence, not for the capped one. A 2024 analytical study opens by stating plainly that actin binding, dermal wound healing, angiogenesis and skin repair are functions of LKKTETQ in its unacetylated form, and that the biological effects of TB-500 itself have not been documented.

That is a narrower gap than it first sounds, and a more interesting one. Nobody is suggesting the cap makes the peptide inert. What the authors are pointing at is that the experiments everybody quotes were run on a slightly different molecule from the one being sold, and that nobody had gone back and repeated them on the capped version.

The same paper then pushed the point further. Having tracked what the capped peptide breaks down into, and tested each breakdown product in a fibroblast wound assay, the authors found that only one of them — a five-residue piece, Ac-LKKTE — produced a significant effect against control. Their conclusion is that the repair activity attributed to TB-500 in the earlier literature may in fact belong to that metabolite rather than to the parent chain.

Read every TB-500 claim through this filter.

A study described as showing what TB-500 does is, more often than not, a study of the whole 43-residue protein, or of the uncapped seven-residue sequence, or — on the newest evidence — of a fragment of a fragment. Those are four different molecules. Ask which one was in the tube before weighing what the result means.

## What Have the Animal and Cell Studies Found?

The published record on this seven-residue sequence is preclinical throughout: cell assays, mice, rats and an animal model of eye injury, with no human arm anywhere in it. Five studies carry most of the weight, and each is listed below with the system it was actually run in, because the system is what decides how far a result travels.

_The principal published studies of the seven-residue thymosin beta-4 fragment, the model system used in each, and what each reported_

| Study | Model system | What was reported |
| --- | --- | --- |
| Philp 2003, Wound Repair and Regeneration | Full-thickness skin wounds in mice aged 26 months | The synthetic seven-residue peptide promoted repair in the aged animals to a degree comparable with the whole protein |
| Philp 2003, FASEB Journal | Human umbilical vein endothelial cell migration, and vessel sprouting from chick aortic arches | The actin-binding motif was essential for angiogenic activity, and matched the whole protein at roughly 50 nanomolar; peptides missing any part of the motif did nothing |
| Rahaman 2024, Journal of Chromatography B | Rat urine, human serum, enzyme preparations and fibroblast scratch assays | Of the capped peptide and its breakdown products, only Ac-LKKTE produced a significant wound-repair effect against control |
| Biçer 2026, Joint Diseases and Related Surgery | Severed and surgically repaired Achilles tendons in rats, assessed at four weeks | Tendons from the arm receiving this peptide withstood more load before failing, and scored better on both histological systems used |
| Lu 2025, ACS Applied Materials & Interfaces | Human corneal epithelial cells and stromal fibroblasts, plus an alkali-burn eye injury model | A gel built to assemble at the wound itself sped epithelial regeneration; the authors describe it as the first ocular use of the peptide |

Two things are worth pulling out of that table. The 2003 angiogenesis result is the strongest single finding in the set, because it is a negative control done properly — shortened versions of the motif were tested alongside the full one and were inactive, which is what makes the claim about the motif specific rather than decorative. And the 2025 ocular work is the newest direction the field has taken, though note what was actually delivered there: a peptide held at the wound by an engineered gel, which is a long way from a peptide dissolved in a vial.

The rat tendon study is reported in full, arm by arm, in [the BPC-157 comparison guide](https://www.australianresearchpeptides.au/articles/bpc-157-vs-tb-500), including what it found when the two compounds were given together.

## Has TB-500 Been Tested in People?

No published trial has given TB-500 to human beings and reported an outcome. The human trial record that people cite belongs to the full-length protein, and the difference between the two is 36 amino acids.

That is checkable in a few minutes rather than taken on trust. Read from the ClinicalTrials.gov registry on 4 September 2026, eighteen interventional records name thymosin beta-4 as the substance being given. Seventeen of those concern the whole protein — dry eye, corneal injury, pressure and venous ulcers, and heart attack — of which eleven have completed, four were withdrawn or stopped early, and two remain open. One of the completed ones is a phase 1a safety study that gave recombinant human thymosin beta-4 intravenously to 54 healthy volunteers.

The eighteenth record is the only one in the registry that mentions TB-500 by name, and it is not a trial.

The registry record that looks real and is not.

Record

NCT07487363

carries a formal title naming the 17-23 fragment, a phase, an industry sponsor, a recruiting status and dose-labelled arms. Its own summary begins by calling itself a fictional example of a registry-style record, and its longer description repeats that it models common data elements rather than describing a study. Registry mirrors and aggregator sites republish the title, phase and status without that disclaimer, which is how it ends up quoted as evidence that a human TB-500 trial is under way. There is no such trial.

A 2026 review in Sports Medicine, written for clinicians dealing with patients who arrive already using these compounds, puts TB-500 in the same group it calls a grey market of unapproved peptides operating outside regulatory oversight, and notes that while several show favourable tissue-repair results in animals, rigorous human safety data are scarce.

## What Are the Side Effects of TB-500?

There is no measured side-effect profile for TB-500 in people, because no controlled human study of it has been run and published. That cuts both ways, and the reassuring direction is the one that gets quoted: a compound nobody has tested cannot honestly be described as well tolerated either.

What does exist is thin and indirect:

- **Cell-level toxicity was looked for and not found.** The 2024 metabolite work tested the capped peptide and each of its breakdown products on fibroblasts and reported no cytotoxicity. That is a dish of cells over hours, not an organism over years.
- **Animal studies ran for weeks, not lifetimes.** The published designs measure a repair window and stop. Nothing follows an animal long enough to see a delayed effect, and nothing at all observes what happens after administration ends.
- **The mechanism itself is the stated concern.** Sport Integrity Australia’s substance page says the parent protein’s ability to extend cell lifespan and promote cell growth is indiscriminate, and that there is serious concern it increases the spread and growth of cancer cells. It adds that sufficient short and long-term studies have not been conducted, so the safety profile remains largely unknown.

A compound that encourages cells to migrate and blood vessels to form is doing, by design, two of the things a tumour needs. Whether that translates into real risk has not been established either way — which is precisely the point. It has not been excluded.

## Is TB-500 Legal in Australia?

TB-500 is a Schedule 4 substance in Australia and also appears in Appendix D of the Poisons Standard, which places it among what NSW Health publishes as prescribed restricted substances. Both “TB-500” and “Thymosin beta 4” are named in that list by name.

Schedule 4 on its own means prescription only. Appendix D is the tighter layer on top: the substances on that list are described as liable to abuse, misuse and diversion, which is the stated reason for more stringent controls on possession as well as on supply. So the control reaches further than the point of sale.

Two consequences follow for anyone reading this page in Australia, and neither is legal advice. There is no registered TB-500 medicine here, so there is nothing for a pharmacist to dispense and no product for a prescriber to write against. And the phrase “research use only” describes what a supplier is selling for; it is not a classification that changes where a substance sits in the Poisons Standard. [In vitro research requirements](https://www.australianresearchpeptides.au/articles/research-use-requirements) sets out what supply on those terms actually means, and anyone whose intended purpose sits outside bench research should take advice from the Therapeutic Goods Administration or a lawyer rather than from a supplier.

## Is TB-500 Banned in Sport?

Yes, at all times, in and out of competition. Sport Integrity Australia’s substance page states that thymosin beta-4 is listed under S2.3 of the 2026 World Anti-Doping Code Prohibited List, the class covering growth factors and growth factor modulators, and that its administration is banned in sport at all times.

Three details on that page are worth knowing before anyone assumes the fragment escapes the parent’s status.

- **TB-500 is listed as another name for the parent.** The page is headed with the protein and gives TB4 and TB-500 among its other names, so the national anti-doping authority treats the two as one substance for prohibition purposes even though the chemistry separates them.
- **No exemption is available.** The page states directly that a Therapeutic Use Exemption would not be granted for thymosin beta-4 in any medical condition.
- **It is not approved anywhere.** The same page records that it holds no Therapeutic Goods Administration approval and is not approved for human use in any country.

Doping-control laboratories have been building detection methods for this peptide since at least 2012, in human plasma and urine and separately in horses, so the assumption that a short fragment is too small to find is out of date by well over a decade.

## How Long Does TB-500 Stay in the Body?

No half-life has been published for TB-500 in any species. What has been published is a breakdown profile, and it is more informative than a single number would have been.

The 2024 analytical study followed the capped peptide and its fragments in the urine of treated rats. A two-residue product, Ac-LK, was the most abundant species over the first six hours. A three-residue product, Ac-LKK, was the long-lived one and was still detectable at 72 hours. Those are rat measurements in urine, and they describe how the molecule is taken apart rather than how long any effect lasts.

Which is the honest answer to the question people are usually asking. Detection window, clearance and duration of effect are three different things, and only the first of them has been measured for this compound at all.

## What Is Still Unknown About TB-500?

Most of what a reader wants to know about TB-500 has not been established. This is the section competitor pages leave out, and it is the one that decides how much weight everything above deserves.

- **No human outcome of any kind.** Nothing published describes what giving this fragment to a person does.
- **Which molecule is active is contested.** The 2024 authors propose that the reported repair activity belongs to a metabolite rather than to the peptide as supplied, and no one has yet tested that proposal against the original experiments.
- **The capped form has been characterised less than the uncapped one.** The foundational activity papers used the uncapped sequence, and they have not been repeated on the acetylated version.
- **No long-term safety observation exists in any species.** Every published animal design measures a treatment window of weeks and ends there.
- **The cancer question is open rather than answered.** A mechanism that promotes cell migration and vessel formation raises a risk that has not been excluded, which is not the same as a risk that has been demonstrated.
- **Nothing has been observed after use stops.** No published work measures anything beyond the end of administration.
- **No comparison against an established treatment exists.** Every controlled arm in the record is untreated or vehicle, never a standard of care.

## What Does Australian Research Peptides Supply?

Australian Research Peptides lists [TB-500](https://www.australianresearchpeptides.au/products/tb-500) under Tissue Repair Research as a freeze-dried powder sealed in a tamper-evident glass vial, in one strength. Nothing on that line can be ordered at present, so what follows describes what is catalogued rather than what is on the shelf.

_The TB-500 vial listed by Australian Research Peptides, with its stock code_

| Vial | Stock code |
| --- | --- |
| 10 mg | ARP-TB500-10 |

Nothing has been published for this compound so far. The [certificate library](https://www.australianresearchpeptides.au/coa) shows which strengths across the range carry a document and which are still waiting, since a report belongs to one batch and travels with it. A certificate settles what is in the glass. It says nothing whatever about what the contents do, which is the separate question this article has been about. [How to read a certificate of analysis](https://www.australianresearchpeptides.au/articles/peptide-testing-purity-coa) sets out where each analytical method stops.

## Common Questions

### Is TB-500 a Steroid?

No. TB-500 is a peptide — a short chain of amino acids — and steroids are a completely different class of molecule built around a four-ring carbon skeleton. The two behave differently, are made differently and act on different targets. The confusion comes from both appearing on the same anti-doping list rather than from any chemical relationship.

### Does TB-500 Have a Published Half-Life?

No half-life for TB-500 has been published in any species. The nearest published figures come from a 2024 study that measured its breakdown products in rat urine, where a two-residue fragment dominated over the first six hours and a three-residue fragment stayed detectable to 72 hours. Any half-life quoted for people is an estimate rather than a measurement.

### Why Is TB-500 Banned in Sport If It Is Not an Approved Medicine?

Anti-doping prohibition and medicines approval are separate systems asking separate questions. The World Anti-Doping Code prohibits substances that could enhance performance, whether or not any regulator has licensed them, and thymosin beta-4 sits in the growth factors class because of its effects on muscle, tendon, ligament and blood vessels. Sport Integrity Australia lists TB-500 as another name for it, and records that no Therapeutic Use Exemption would be granted.

### Does a Certificate of Analysis Say Whether TB-500 Works?

No. A certificate of analysis reports identity and purity: what the material in a particular vial is, and what proportion of it is that substance. Those are chemistry questions. Whether the substance produces an effect is a separate question answered by studies, not by batch documents, and for TB-500 those studies stop short of people.

In vitro research purposes only.

This article reports published laboratory research and public regulatory records about a peptide fragment. It is not medical, therapeutic or dosing guidance, it makes no claim that any effect described in an animal or a cell assay occurs in a person, and it is not a quality, safety or suitability statement covering any use in a person or an animal. All products supplied by Australian Research Peptides are for in vitro research purposes only.

## Related Guides

- [BPC-157 vs TB-500How the two tissue-repair peptides differ, and what happened when a study gave both at once.](https://www.australianresearchpeptides.au/articles/bpc-157-vs-tb-500)
- [How to read a certificate of analysisWhich analytical methods settle the identity question, and the point past which they say nothing at all.](https://www.australianresearchpeptides.au/articles/peptide-testing-purity-coa)
- [MOTS-C: what the research showsAnother compound whose evidence is cells and mice, and the one registered trial that has begun.](https://www.australianresearchpeptides.au/articles/mots-c-research-trial-tracker)
- [In vitro research requirementsThe terms this material is supplied under, and the laboratory practice that comes with holding it.](https://www.australianresearchpeptides.au/articles/research-use-requirements)

TB-500 reaches Australian benches through Australian Research Peptides as a freeze-dried vial in the Tissue Repair Research range, though that line is presently unstocked, posted domestically rather than cleared across a border. For in vitro research purposes only.

## References

1. [Philp D, Badamchian M, Scheremeta B, et al. Wound Repair and Regeneration 2003;11(1):19-24 (PMID 12581423)](https://pubmed.ncbi.nlm.nih.gov/12581423/)
2. [Philp D, Huff T, Gho YS, Hannappel E, Kleinman HK. FASEB Journal 2003;17(14):2103-2105 (PMID 14500546)](https://pubmed.ncbi.nlm.nih.gov/14500546/)
3. [Sosne G, Qiu P, Goldstein AL, Wheater M. "Biological activities of thymosin beta4 defined by active sites in short peptide sequences." FASEB Journal 2010;24(7):2144-2151 (PMID 20179146)](https://pubmed.ncbi.nlm.nih.gov/20179146/)
4. [Esposito S, Deventer K, Goeman J, Van der Eycken J, Van Eenoo P. Drug Testing and Analysis 2012;4(9):733-738 (PMID 22962027)](https://pubmed.ncbi.nlm.nih.gov/22962027/)
5. [Rahaman KA, Muresan AR, Min H, et al. "Simultaneous quantification of TB-500 and its metabolites in in-vitro experiments and rats by UHPLC-Q-Exactive orbitrap MS/MS and their screening by wound healing activities in-vitro." Journal of Chromatography B 2024;1235:124033 (PMID 38382158)](https://pubmed.ncbi.nlm.nih.gov/38382158/)
6. [Lu P, Shan M, Peng C, et al. "Alkaline Phosphatase-Triggered Spatiotemporal Repair of Corneal Injury with TB500 Peptide Hydrogel." ACS Applied Materials & Interfaces 2025;17(50):67503-67518 (PMID 41359360)](https://pubmed.ncbi.nlm.nih.gov/41359360/)
7. [Biçer O, Adanir O, Güleryüz Y, et al. "Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study." Joint Diseases and Related Surgery 2026;37(3):822-837 (PMID 42542926)](https://pubmed.ncbi.nlm.nih.gov/42542926/)
8. [Mendias CL, Awan TM. "Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance." Sports Medicine 2026;56(8):1921-1935 (PMID 41966639)](https://pubmed.ncbi.nlm.nih.gov/41966639/)
9. [Sport Integrity Australia — Thymosin Beta-4 substance information page](https://www.sportintegrity.gov.au/what-we-do/anti-doping/substance-education/thymosin-beta-4)
10. [NSW Health, Schedule 4 Appendix D drugs — prescribed restricted substances](https://www.health.nsw.gov.au/pharmaceutical/Pages/sch4d.aspx)
11. [ClinicalTrials.gov — NCT04555824, phase 1a study of recombinant human thymosin beta-4 in healthy volunteers](https://clinicaltrials.gov/study/NCT04555824)
12. [ClinicalTrials.gov — NCT07487363, a demonstration example record rather than a real trial](https://clinicaltrials.gov/study/NCT07487363)
13. [UniProt Knowledgebase entry P62328 (TYB4_HUMAN), thymosin beta-4 — flat-file record](https://rest.uniprot.org/uniprotkb/P62328.txt)
14. [PubChem Compound CID 62707662 (TB-500, Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln-OH)](https://pubchem.ncbi.nlm.nih.gov/compound/62707662)

## Related compounds

- [TB-500](https://www.australianresearchpeptides.au/products/tb-500)
- [BPC-157 + TB-500](https://www.australianresearchpeptides.au/products/bpc-157-tb-500)

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_All products supplied by Australian Research Peptides are for in vitro research purposes only._