TB-500: what it is, what the studies show and where it stands
TB-500 is a product name. The peptide identified in it is Ac-LKKTETQ, the acetylated fragment made of amino acids 17 to 23 of thymosin beta-4.
At a glance
US Not approved
Canada Not authorized
Group Healing and recovery
Sources 17
Checked 10 Oct 2026What is TB-500?
TB-500 is a product name. The peptide identified in it is Ac-LKKTETQ, the acetylated fragment made of amino acids 17 to 23 of thymosin beta-4. It is a 7-amino-acid piece, not the full 43-amino-acid thymosin beta-4 that was used in the human trials. [1]
Other names: TB500, Ac-LKKTETQ, N-acetylated LKKTETQ, thymosin beta-4 fragment 17-23.
How it has been given to people: no human use on record.
Looking for doses? TB-500 dosage chart and vial math
Is TB-500 approved in the US and Canada?
United States: Not FDA approved. FDA lists the thymosin beta-4 fragment LKKTETQ, also known as TB-500, among bulk substances that were in compounding category 2 until the nominations were withdrawn, and says it has found no human exposure data for it. [13]
Canada: Not authorized in Canada. Health Canada names TB-500 among unauthorized injectable peptide drugs it has seized (advisory of 9 April 2026). [16]
Both were checked on 10 Oct 2026 against the regulators' own product databases.
Which approved products contain TB-500?
No approved medicine containing TB-500 was found in the US or Canada. Anything sold under this name is not a regulated product, so there is no label to check a dose against.
What human studies of TB-500 exist?
The 15 findings listed here: 5 from randomized human trials, 1 from smaller or observational human studies and 9 from animal or lab work.
Full-length thymosin beta-4 is a 43-amino-acid peptide. A synthetic copy applied to venous leg ulcers was tested in a Phase 2 trial of 73 patients, where the 0.03% strength was reported as possibly speeding healing. [8]
Full-length synthetic thymosin beta-4 was given by vein to healthy volunteers in four groups of 10 at 42, 140, 420 or 1260 mg, as a single dose and then daily for 14 days. This was thymosin beta-4, not TB-500. [5]
That intravenous study reported no dose-limiting toxicity or serious adverse events over 14 days. [5]
Recombinant human thymosin beta-4 (code NL005) was given by vein to 54 healthy volunteers as single doses from 0.05 to 25.0 micrograms per kg; 30 volunteers were enrolled for daily doses over 10 days. This was thymosin beta-4, not TB-500. [6]
Eye drops containing 0.1% thymosin beta-4 (RGN-259) were tested in a Phase 3 trial in neurotrophic keratopathy: complete healing at 4 weeks in 6 of 10 treated and 1 of 8 on placebo (p = 0.0656). This was thymosin beta-4, not TB-500. [7]
In a clinic chart review, 4 patients were given a product called TB4 together with BPC 157 into the knee joint. The abstract does not say whether it was full-length thymosin beta-4 or the TB-500 fragment, and gives no dose. [10]
In that doping-control study, horses were given a single dose of TB-500 containing 10 mg of the peptide so that it could be detected in urine and plasma. It was not a study of benefit. [2]
In rats given TB-500 into the abdomen for four weeks after Achilles tendon repair, tendon structure scores and strength were better than in controls. The abstract itself calls TB-500 synthetic thymosin beta-4. [9]
In the same rat study, giving TB-500 together with BPC-157 added nothing over either one alone. [9]
A 2026 review for orthopaedic physicians found that thymosin beta-4 and TB-500 helped tissue repair in preclinical models but that human orthopaedic data are lacking. [11]
Laboratory analysis of a TB-500 product identified its peptide as Ac-LKKTETQ, the N-terminal acetylated 17-23 fragment of human thymosin beta-4. [1]
An equine doping-control study described TB-500 in 2012 as a veterinary preparation whose key ingredient is LKKTETQ with an acetyl group added to the N-terminus. [2]
A 2024 metabolism study states that the biological effects of TB-500 itself have not been documented. [3]
In that study, only one breakdown product (Ac-LKKTE) showed significant wound-healing activity in fibroblast cell tests; the authors suggest activity credited to TB-500 may come from this metabolite. [3]
Analysis of TB500 and TB1000 products sold online found that what they contain does not consistently match how they had been described. [4]
What are the side effects of TB-500?
Reported in human studies or on a label:
- No human safety data exist for TB-500 itself. FDA says it lacks the information to know whether it would cause harm in humans. [13]
- FDA says compounded versions of the fragment may carry a risk of immune reactions because of possible clumping and peptide impurities. [13]
- For full-length thymosin beta-4 given by vein (not TB-500), adverse events in healthy volunteers were infrequent and mild or moderate. [5]
- For recombinant full-length thymosin beta-4 given by vein (not TB-500), adverse events were mild to moderate. [6]
How does TB-500 compare with others in its group?
These are the peptides filed under healing and recovery. The last column says whether a randomized human trial is on record for each.
| Peptide | US | Canada | Half-life | Randomized human trial |
|---|---|---|---|---|
| BPC-157 | Not approved | Not authorized | Not found | No |
| TB-500 | Not approved | Not authorized | Not found | Yes |
| KPV | Not approved | Not authorized | Not found | No |
| ARA-290 | Not approved | Not authorized | About 20 minutes after injection under the skin and about 2 minutes after intravenous injection, as given in a 2016 review written by the trial group (full text). | Yes |
| MGF | Not approved | Not authorized | Not found | No |
| Cartalax | Not approved | Not authorized | Not found | No |
What could not be found
These were searched for and did not turn up. They are listed so a missing number is not mistaken for a hidden one.
- Any human study of TB-500 (Ac-LKKTETQ): none found. PubMed searches for TB-500, TB500 and Ac-LKKTETQ with patients, volunteers, case report or clinical trial returned only reviews and doping-test methods.
- Any human dose of TB-500, by any route. The doses list is empty on purpose: thymosin beta-4 trial doses are a different molecule given by a different route and are recorded under evidence instead.
- Any human study of thymosin beta-4 or TB-500 injected under the skin. A PubMed search for thymosin beta-4 with subcutaneous and patients or volunteers returned only laboratory papers.
- A human half-life for TB-500. For full-length thymosin beta-4 the intravenous study abstract [5] says half-life rose with dose but gives no figure.
- An approved product or label for TB-500 or thymosin beta-4 in the US or Canada.
- What the TB4 product injected in [10] actually was, and its dose.
- Human study of TB-500 or thymosin beta-4 given together with BPC-157: only the 4 knee patients in [10]. No trial was found.
- Posted results of the RGN-259 dry eye Phase 3 trials (ARISE) were not opened in this session.
TB-500 questions
Is TB-500 approved in the US?
Not FDA approved. FDA lists the thymosin beta-4 fragment LKKTETQ, also known as TB-500, among bulk substances that were in compounding category 2 until the nominations were withdrawn, and says it has found no human exposure data for it.
Is TB-500 authorized in Canada?
Not authorized in Canada. Health Canada names TB-500 among unauthorized injectable peptide drugs it has seized (advisory of 9 April 2026).
Has TB-500 been tested in a randomized human trial?
Yes. At least one randomized human trial is listed on this page.
Sources
Each one was opened on 10 Oct 2026 and matched to the line it supports.
- Esposito S et al. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential. Drug Test Anal 2012. PubMed 22962027.
- Ho EN et al. Doping control analysis of TB-500, a synthetic version of an active region of thymosin beta4, in equine urine and plasma by liquid chromatography-mass spectrometry. J Chromatogr A 2012. PubMed 23084823.
- Rahaman KA 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. J Chromatogr B Analyt Technol Biomed Life Sci 2024. PubMed 38382158.
- Delcourt V et al. TB500/TB1000 and SGF1000: A scientific approach for a better understanding of misbranded and adulterated drugs. Drug Test Anal 2023. PubMed 36482504.
- Ruff D et al. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers. Ann N Y Acad Sci 2010. PubMed 20536472.
- Wang X et al. A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin beta4 in healthy Chinese volunteers. J Cell Mol Med 2021. PubMed 34346165.
- Sosne G et al. 0.1% RGN-259 (Thymosin beta4) Ophthalmic Solution Promotes Healing and Improves Comfort in Neurotrophic Keratopathy Patients in a Randomized, Placebo-Controlled, Double-Masked Phase III Clinical Trial. Int J Mol Sci 2022. PubMed 36613994.
- Guarnera G et al. The effect of thymosin treatment of venous ulcers. Ann N Y Acad Sci 2010. PubMed 20536470.
- Bicer O et al. Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study. Jt Dis Relat Surg 2026. PubMed 42542926.
- Lee E et al. Intra-Articular Injection of BPC 157 for Multiple Types of Knee Pain. Altern Ther Health Med 2021. PubMed 34324435.
- Mayfield CK et al. Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians. Am J Sports Med 2026. PubMed 41476424.
- TB-500 (Thymosin Beta 4 17-23 Fragment) for Cardiovascular Biomarkers in Stable ASCVD ClinicalTrials.gov 2026. clinicaltrials.gov. Trial NCT07487363.
- Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks US Food and Drug Administration 2026. fda.gov.
- Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act US Food and Drug Administration 2026. fda.gov.
- World Anti-Doping Code International Standard Prohibited List 2026 World Anti-Doping Agency 2026. wada-ama.org.
- Think twice before injecting peptides bought online: unauthorized products can seriously harm you Health Canada 2026. recalls-rappels.canada.ca.
- Unauthorized injectable peptide drugs seized from Optimum Wellness Centre in Calgary, Alberta may pose serious health risks Health Canada 2025. recalls-rappels.canada.ca.
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