The short version

Plain English first. Everything below this section is the same material with the sources, the numbers and the caveats attached.

What TB-500 is

TB-500 is Ac-LKKTETQ, a synthetic peptide of seven amino acids with an acetyl group on the front end. That is the compound the FDA names, the compound anti-doping laboratories hold reference standards for, and the compound every supplier in this market sells under the name. It is made by solid-phase synthesis and supplied as a lyophilised powder.

Those are the figures to check a certificate against. The molecular weight is the quickest check there is: 889.0 Da is the number that should appear.

What the published work says it does

The activity attached to the LKKTETQ sequence was mapped by Sosne and colleagues in 2010. Their paper is the primary source for what this peptide is understood to do, and it is worth reading what it actually claims:

Sosne 2010, verbatim: "the amino-terminal site containing 4 aa (Ac-SDKP) that generally blocks inflammation and reduces fibrosis… a short sequence containing LKKTETQ, the central actin-binding domain (aa 17-23) plus 1 additional amino acid (Q), promotes angiogenesis, wound healing, and cell migration."

So the published activity for this sequence is angiogenesis, cell migration and wound healing. That is the mechanism to expect it to be studied for, and the tissue work below is consistent with it.

It binds actin

LKKTET is the central actin-binding motif, and binding actin is the structural basis for the migration and wound-healing work. Irobi and colleagues solved the relevant structure in 2004. What that paper describes is a contact at the centre of the actin monomer, which is what this sequence makes.

Pharmacokinetics

There is no published human pharmacokinetic data for TB-500. The FDA states the position more bluntly than we would dare to: it has not identified any human exposure data for this substance at all.

What does exist is metabolism work, not pharmacokinetics. A WADA-funded project characterised how Ac-LKKTETQ breaks down — sequential cleavage from the C-terminus, with the N-terminal acetyl group protecting that end — in human liver microsomes, S9 fraction, plasma and serum. That work exists so that anti-doping laboratories can detect the metabolites, and it established detection limits down to 50 pg/mL. It is chemistry in a tube. It tells you nothing about half-life, distribution or bioavailability in a person.

What the evidence shows

The honest summary is short: a substantial animal literature, and almost nothing on TB-500 itself. The best source on that is a review that went looking.

Tendons, ligaments, muscle — the thing it is actually sold for

A peer-reviewed scoping review published in June 2026 screened 1,772 records and included 80 studies. Its finding, verbatim:

One study, out of eighty, out of 1,772 screened, looked at TB-500 itself. The review is recent, peer-reviewed and specifically went looking for this evidence, which makes it the strongest statement available about how much of it exists.

What the animal work looks like

The tissue-repair literature is rodent and rabbit work on tendon, cornea and cardiac tissue, with cell-culture work underneath it. Read on its own terms it is a reasonable preclinical case for the mechanism in the table above — angiogenesis, migration, wound healing.

What it is not is evidence of an effect in a person. There is no randomised human trial to translate it, which is the gap the review above measured. We would rather set that out than imply a human result exists.

Reconstitution

A 10 mg vial:

10 mg ÷ 2 mL = 5 mg/mL, so one U-100 unit carries 50 mcg and a 2 mg draw is 40 units. At 5 mL a 2 mg draw fills a whole U-100 syringe. The calculator will do this for any volume.

Direct the stream down the inside wall of the vial rather than onto the cake, swirl rather than shake, and label the vial with the resulting concentration — not the volume you added. The full method is in the reconstitution guide.

Reported protocols

We do not publish dosing figures for this compound, and the reason is not caution for its own sake.

The schedules circulating for TB-500 — a loading period followed by maintenance, split weekly, injected near the site of an injury — have no trial behind them in any species. We tried to trace them to a primary source and could not. No study has compared local to distant administration. No study has tested a loading-then-maintenance schedule. The routes used in the systemic animal work are not the route the conventional schedules describe.

So a figure printed here would be repeating a convention and lending it our name, which is the opposite of what this library is for. If you are designing research with this compound, the literature in the references is the place to start, and the honest answer is that it will not give you a schedule either.

Storage

Lyophilised, sealed, cold, dark and dry, this is a stable solid. The handling conventions in our storage guide apply. They are conventions carried across from peptides generally rather than published stability data for this compound, and we say so rather than implying a study exists.

Reconstituted in bacteriostatic water, the limiting figure is microbiological rather than chemical: the benzyl alcohol preservative is validated for 28 days. That is the number to work to for a multi-draw vial, and it is not a claim about when the peptide degrades. Our FAQs explain where the figure comes from.

Reported effects

There is no human safety data for TB-500, because there is no human exposure data for it. What follows is mechanism and preclinical work, labelled as such.

The oncology question, which deserves to be taken seriously

The mechanism sold as the benefit — angiogenesis plus cell migration — is also the mechanism of metastasis. That is not a rhetorical point: it is the same cell behaviour described in the same terms.

The experiment that tested it directly is Yoon and colleagues, 2021, who applied peptides of this kind to SKOV3 ovarian cancer cells. They stimulated migration and invasion of those cells — including the peptides lacking the actin-binding motif, so the comfortable inference that a short peptide cannot do much is the wrong one.

No human study has assessed cancer risk from administering this compound. We looked, and FDA independently records that no human exposure data exists at all. So the concern can be neither confirmed nor dismissed. Existing or suspected malignancy is a serious theoretical contraindication here, and it is grounded in primary literature rather than boilerplate.

What the FDA recorded

The agency records a risk of immunogenicity for certain routes of administration, from the potential for aggregation and from peptide-related impurities. Its own summary of the position is worth quoting directly: "FDA lacks important information regarding any safety issues raised by this drug, including whether it would cause harm if administered to humans."

Aggregation is the reason the storage note above says not to freeze a reconstituted vial. It is also the reason purity on a certificate is worth reading rather than glancing at.

Regulatory status

Approval. TB-500 is not an approved drug anywhere in the world, in any form, for any indication.

United States. TB-500 was nominated for the FDA's compounding lists and the nomination was later withdrawn. It is not in category 2 of the interim policy. It is also not an approved drug and not lawfully compoundable.

That position moved in July 2026. On 23 July 2026 FDA's Pharmacy Compounding Advisory Committee reviewed TB-500 alongside BPC-157, KPV and MOTS-c, under docket FDA-2025-N-6895. FDA's own position going into the meeting was that none of the peptides before it should be added to the 503A bulks list; legal commentators reporting from the room record the committee voting 8 to 6 with one abstention to recommend adding TB-500 anyway.

A committee recommendation is advice, not a rule. FDA is not bound by it, formal rulemaking has not happened, and nothing about the legal status of this compound has changed — in the United States or in Canada. We record it because you will see it reported as though it had.

Canada. Health Canada's public advisory of 9 April 2026 names TB-500 among fourteen peptides sold online, states that peptides are generally regulated as prescription drugs in Canada, and states that research-use-only labelling "does not make these products legal or exempt from regulatory requirements." It is not a controlled substance under the Controlled Drugs and Substances Act. The advisory is linked in the references and is worth reading directly.

Sport. The 2026 WADA Prohibited List, in force from 1 January 2026, section S2.3, growth factors and growth factor modulators, names TB-500 explicitly. Prohibited at all times, in and out of competition. Anti-doping laboratories hold reference standards for its metabolites with detection limits down to 50 pg/mL, so this is a substance they can actually find. If you are a tested athlete, that is the only sentence on this page you need.

Sentient Biogenix supplies TB-500 for laboratory research use only. It is not for human or veterinary use.

Questions we actually get

What exactly is in the vial?

Ac-LKKTETQ, a synthetic seven-residue peptide at 889.0 Da, supplied as a lyophilised powder. It is the same TB-500 sold across this market. Our certificate for the lot reports 99.23% purity and 10.31 mg of content, and it is published in full in the certificate register.

Do the anti-inflammatory claims hold up?

We could not find a published study demonstrating an anti-inflammatory or antifibrotic effect for TB-500. It is claimed constantly across the market. If someone shows us the paper we will put it on this page, and until then we are not going to repeat it.

What about tendon and ligament healing?

That is the preclinical case, and it is a real one — rodent and rabbit tendon work, plus cell culture. A 2026 scoping review screened 1,772 records and found no human interventional study in tendon, ligament, muscle, bone or cartilage. So: animal evidence, no human evidence.

Is it safe because it is a short peptide?

That reasoning does not hold up. In the one experiment that tested the question directly, peptides of this kind — including those lacking the actin-binding motif — stimulated migration and invasion of ovarian cancer cells. No human study has assessed cancer risk from administering it. That is an unanswered question, not a resolved one.

Is it banned in sport?

Yes. It is named on the 2026 WADA Prohibited List under S2.3, prohibited at all times, and the laboratories can detect its metabolites down to 50 pg/mL. If you are tested, do not go near it.

References

1. 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):2144–51. pubmed.ncbi.nlm.nih.gov — the sequence-to-activity mapping, and the source for angiogenesis, wound healing and cell migration being the activity attached to LKKTETQ.
2. Irobi E, Aguda AH, Larsson M, et al. Structural basis of actin sequestration by thymosin-β4: implications for WH2 proteins. EMBO Journal 2004;23:3599–3608. link.springer.com — the structural work behind LKKTET as the central actin-binding contact.
3. McGuire F, Hughes E, Maak T, Cushman DM. Thymosin beta-4 and TB-500 in tissue healing, regeneration, and musculoskeletal repair: a scoping review. Applied Sciences 2026;16(12):6202. mdpi.com — 1,772 records screened, 80 included, no human interventional musculoskeletal study, and direct TB-500 evidence limited to a single included study.
4. Yoon HJ, Oh YL, Ko EJ, et al. Effects of thymosin β4-derived peptides on migration and invasion of ovarian cancer cells. Genes & Genomics 2021;43(8):987–93. pubmed.ncbi.nlm.nih.gov — every peptide tested, including those without the actin-binding motif, stimulated migration and invasion of SKOV3 ovarian cancer cells.
5. US Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. fda.gov — the immunogenicity and aggregation language, and the quoted sentence about what FDA lacks, in the nominated-but-withdrawn table.
6. World Anti-Doping Agency. The 2026 Prohibited List, in force 1 January 2026, section S2.3, growth factors and growth factor modulators, which names TB-500. Read via the Austrian Federal Law Gazette's official reproduction (BGBl. III Nr. 219/2025) because WADA blocks automated access to its own copy.
7. Health Canada. Think twice before injecting peptides bought online: unauthorized products can seriously harm you. Public advisory, 9 April 2026. recalls-rappels.canada.ca

Where we could not open a source, this page says so rather than quoting a figure we have not read. Where a claim circulates without a primary source behind it — the anti-inflammatory activity, the dosing schedules, the stated half-lives — this page says that too, instead of repeating it. If you find a paper we have missed, send it and we will add it.