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documented protocols

TB-500: what is documented about dosing

What published work used, in which species and by which route, reported as a record rather than as a protocol.

Last Reviewed Editorial policy Methodology

Published work on TB-500 records what was given in each experiment, in the model that experiment built. That record is set out below with the species, the molecule and the route named on every line.

Every figure in it belongs to an animal study, a cell assay or a regulatory document. No study has established an amount for a person, and FDA states it identified no clinical study in humans assessing the pharmacokinetics of either form by any route.

Where a source states an amount, this page names the source and the design and does not reproduce the number. That applies equally to the animal studies, to the nomination's proposed product and to the registered protocol, and the reason is on the editorial policy page: a figure lifted out of a study and printed on a page a consumer reads becomes an instruction whatever hedge sits around it.

Not medical advice

This page reports what has been documented about a compound. It is not medical advice, not a diagnosis, not a dosing protocol, and not a recommendation to obtain or use anything described here. Talk to a licensed clinician about anything concerning your health. Read the full disclaimer.

Reviewed against editorial standards Updated

What this page reports, and what it does not

We report what has been documented. We do not prescribe what should be done.

Nothing here is a dosing recommendation. Statements about dosing reflect community and research reports only.

No trial established an amount of TB-500 for a person. Most of the rows below record what a published study gave to its animals or its cells, in the model that study built, with the species and the route named on the line. One row records that other figures circulate in community write-ups, and that this site does not republish them. Nothing here is a protocol, nothing here is scaled for a person, and this site publishes no preparation steps, no administration technique and no equipment. The reasoning is in the editorial policy.

Commonly cited protocols (extrapolated, not validated)

What published studies gave, in which species and by which route, and what circulates elsewhere. The source class is named on every row, and none of it is a clinical protocol
StudyWhat was givenFrequencyDurationNotes
Rat Achilles tendon, into the abdominal cavity. Biçer 2026 [4]TB-500, and a second arm giving it together with BPC-157. The paper states amounts scaled to body weight. This page does not reproduce themStated in the paper. Not reproduced hereFour weeks of treatment, with measurement at the endThirty-two rats in four groups of eight. The only published study in the tissue this compound is sold for, and the route is a laboratory route rather than a marketed one
Rat metabolism, into the abdominal cavity. Rahaman 2024 [5]TB-500 free base. The paper states an amount scaled to body weight and FDA repeats it. This page does not reproduce itSingle administrationSampling to 72 hoursThe study that mapped the breakdown products. Its purpose was measurement rather than effect
Thoroughbred geldings, under the skin. Ho 2012 [6]TB-500 free base, at a single stated amount this page does not reproduceSingle administrationPlasma and urine sampling out to 10 hoursThe only in-vivo exposure measurement in any species. A doping-control study, run to establish detection rather than effect
Aged mice, topical. Philp 2003 [3]The plain non-acetylated heptapeptide LKKTETQ, alongside arms of thymosin beta-4 and vehicle. Concentrations and volumes are in FDA's reading of the paper and are not reproduced hereStated in the paper. Not reproduced hereHistology at day 7A different molecule from the one sold, which is why this row cannot be read as a TB-500 amount. FDA states the two cannot be extrapolated between
Scratched fibroblast cultures. Rahaman 2024 [5]TB-500 free base and each of its breakdown products, at one concentration, the same for every molecule testedSingle treatment per assayPer the assayCells in a dish. A culture concentration is not an amount for a body and does not convert into one, and FDA's recorded caveat is that no concentration-response analysis was run
The nominated product, as submitted to FDA [20]The nomination proposes a lyophilised powder at a stated strength for injectable routes. This page reproduces neither the strength nor the routesNot specified in the nominationNot specified in the nominationA nomination is a request for a substance to be added to a compounding list. FDA proposed against adding either form, and the nomination was itself withdrawn
The registered protocol, NCT07487363 [25]The record states that dose levels are protocol-defined and are not provided in the public example. There is nothing here to reproduceThree sequential cohorts, per the registered design12 weeks of safety follow-up per the registered designThe record describes itself as a fictional example of a registry-style record, so nothing in its protocol describes a trial that is happening
Vendor listings and community write-upsFigures circulate, including vial strengths FDA catalogued from seller websites. This site does not republish any of themFigures circulateFigures circulateNo study established an amount for a person, so every figure in circulation is an extrapolation from an animal experiment, a copy of a product label, or has no origin at all

Two features of that table decide how much any of it is worth. The first is the route. Every in-vivo figure for the acetylated fragment comes from the abdominal cavity of a rodent or from under the skin of a horse, and neither maps onto anything a person would do. Scaling an amount between species is unreliable even between two mammals given the same way, and none of these was.

The second is which molecule each row describes. Three of the eight rows are not TB-500 at all: one is the plain heptapeptide, one is a breakdown product, and one is a nomination document rather than an experiment. Reading the table as a single set of amounts for one substance is the error the whole page exists to prevent.

Our takeThe most useful sentence anyone can write about TB-500 amounts is that the only species with a measured blood level is the horse, and the number there is picograms per millilitre.

Main routes people compare

Injected

Injection is how the product is sold and it is the route with the least relevant published work. Two rat studies used the abdominal cavity, which is a laboratory route chosen for reliable systemic exposure in a small animal [4] [5]. One equine study used the route under the skin and measured blood rather than an outcome [6]. No published study has given TB-500 by any injected route to a person, for any purpose.

This site publishes no preparation procedure, no administration technique and no equipment, on any route, and the reasoning is on the editorial policy page. [Animal] [4] [5] [6]

Topical

The topical record belongs to two other molecules. The 2003 aged-mouse study applied the plain non-acetylated heptapeptide and the parent protein to punch wounds [3], and FDA's position is that a result with the plain form does not carry to the acetylated one.

No published study has applied TB-500 itself to skin, in any species. A reader who has seen this compound described as having topical wound-healing evidence has seen the 2003 study attributed to the wrong molecule. [Animal] [3]

Into an eye, as part of a gel

One 2025 study delivered TB500 to a mouse cornea, and it did so as a covalent conjugate that assembles itself into a nanofibre gel at the wound site rather than as free peptide in solution [7]. The delivery material is the paper's subject and nothing in the result separates the two.

Nobody sells this compound for eyes, so the row is here for completeness rather than because it addresses a marketed route. [Animal] [7]

What is said about cycle length and timing

Cycle lengths, loading phases and rest periods circulate for TB-500 as they do for everything sold beside it, and none of them came from a study of this compound, because no study has run it in a person for any length of time.

The published durations are short and they belong to animals: four weeks of treatment in the rat tendon study [4], sampling out to 72 hours in the rat metabolism study [5], and sampling out to 10 hours in the horse [6]. The longest anything has been given to any animal in a published TB-500 experiment is four weeks.

Timing claims, with or without other products, have no published basis in either direction, because no pharmacokinetic study of this compound exists in a person.

Talk to a licensed clinician about anything concerning your health.

Frequently asked questions

Is there a documented TB-500 amount for a person?

No, and the absence is complete rather than partial. FDA states it identified no clinical study in humans assessing the pharmacokinetics or pharmacodynamics of TB-500 free base or TB-500 acetate by any route, and no published study has given the compound to a person for any purpose. Every figure that exists belongs to a rat, a horse or a cell culture.

Why does this page not reproduce the animal amounts?

Because a species-tagged number is still a number a reader can scale, and body-weight scaling between species is unreliable even between two mammals given by the same route. None of these studies used a route a person would use. Naming the species, the route, the duration and the design carries everything the record supports without supplying an amount.

What about the registered trial's protocol?

There is nothing in it to reproduce. The record states that its dose levels are protocol-defined and are not provided in the public example, which is consistent with its brief summary stating that the record is a fictional example of a ClinicalTrials.gov-style record rather than a study.

Does the cell culture concentration mean anything for a product?

Not directly, and in this case the interesting part is not the number but the comparison. TB-500 and each of its breakdown products were tested at the same concentration in the same scratch assay, and the compound produced no closure while one breakdown product did. FDA's recorded caveat is that no concentration-response analysis was run, so even that comparison rests on a single point.

Which route has the most published work behind it?

The abdominal cavity of a rodent, which is not a route anyone uses. Two of the three in-vivo studies of the acetylated fragment used it. The route with the only measured blood levels is under the skin of a horse.

Does this site publish preparation steps?

No. No preparation procedure, no administration technique and no equipment appears anywhere on this site, for any compound. That is a standing rule rather than a judgement about TB-500, and the reasoning is on the editorial policy page.

References

  1. Esposito S, Deventer K, Goeman J, Van der Eycken J, Van Eenoo P. 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. PMID 22962027 DOI 10.1002/dta.1402
  2. Sosne G, Qiu P, Goldstein AL, Wheater M. Biological activities of thymosin beta4 defined by active sites in short peptide sequences. FASEB J. 2010. PMID 20179146 DOI 10.1096/fj.09-142307
  3. Philp D, Badamchian M, Scheremeta B, Nguyen M, Goldstein AL, Kleinman HK. Thymosin beta 4 and a synthetic peptide containing its actin-binding domain promote dermal wound repair in db/db diabetic mice and in aged mice. Wound Repair Regen. 2003. PMID 12581423 DOI 10.1046/j.1524-475x.2003.11105.x The peptide arm used the non-acetylated heptapeptide LKKTETQ, which is not the molecule sold as TB-500
  4. Biçer O, Adanir O, Güleryüz Y, Balci EC, Dinçel YM, Yenigün MY, Aydin C, Bayrak BY. Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study. Jt Dis Relat Surg. 2026. PMID 42542926 DOI 10.52312/jdrs.2026.2951
  5. Rahaman KA, Muresan AR, Min H, Son J, Han HS, Kang MJ, Kwon OS. 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. PMID 38382158 DOI 10.1016/j.jchromb.2024.124033
  6. Ho EN, Kwok WH, Lau MY, Wong AS, Wan TS, Lam KK, Schiff PJ, Stewart BD. Doping control analysis of TB-500, a synthetic version of an active region of thymosin β₄, in equine urine and plasma by liquid chromatography-mass spectrometry. J Chromatogr A. 2012. PMID 23084823 DOI 10.1016/j.chroma.2012.09.043
  7. Lu P, Shan M, Peng C, Ji W, Yang T, Yang Z, Zhang Z, Wang Y. Alkaline Phosphatase-Triggered Spatiotemporal Repair of Corneal Injury with TB500 Peptide Hydrogel. ACS Appl Mater Interfaces. 2025. PMID 41359360 DOI 10.1021/acsami.5c14652 Administered as a covalent peptide conjugate that self-assembles into a gel, not as free TB-500
  8. Ou H, Chen R, Zhou L, Zhang Y, Zhao S, Yang Z. Thymosin β4-derived peptides alleviate neuroinflammation and neurite atrophy in both in vitro models and in vivo 5 × FAD mice: A potential therapy for memory improvement in Alzheimer's disease. Int Immunopharmacol. 2026. PMID 41443105 DOI 10.1016/j.intimp.2025.116097 TB500 is reported together with Ac-SDKP throughout; no arm isolates either peptide
  9. Delcourt V, Garcia P, Chabot B, Barnabé A, Bouscarel M, Loup B, Popot MA, Bailly-Chouriberry L. TB500/TB1000 and SGF1000: A scientific approach for a better understanding of misbranded and adulterated drugs. Drug Test Anal. 2023. PMID 36482504 DOI 10.1002/dta.3421
  10. Zvereva I, Semenistaya E, Krotov G, Rodchenkov G. Comparison of various in vitro model systems of the metabolism of synthetic doping peptides: Proteolytic enzymes, human blood serum, liver and kidney microsomes and liver S9 fraction. J Proteomics. 2016. PMID 27569051 DOI 10.1016/j.jprot.2016.08.016
  11. Sosne G, Dunn SP, Kim C. Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial. Cornea. 2015. PMID 25826322 DOI 10.1097/ICO.0000000000000379 A trial of thymosin beta-4, the parent protein, not of TB-500
  12. Sosne G, Ousler GW. Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment (CAE™) model. Clin Ophthalmol. 2015. PMID 26056426 DOI 10.2147/OPTH.S80954 A trial of thymosin beta-4, the parent protein, not of TB-500
  13. Sosne G, Kleinman HK, Springs C, Gross RH, Sung J, Kang S. 0.1% RGN-259 (Thymosin ß4) 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. PMID 36613994 DOI 10.3390/ijms24010554 A trial of thymosin beta-4, the parent protein, not of TB-500
  14. Sosne G. Thymosin beta 4 and the eye: the journey from bench to bedside. Expert Opin Biol Ther. 2018. PMID 30063853 DOI 10.1080/14712598.2018.1486818 Indexed by PubMed as a review and a personal narrative, not as a study
  15. Shah R, Reyes-Gordillo K, Rojkind M. Thymosin β4 inhibits PDGF-BB induced activation, proliferation, and migration of human hepatic stellate cells via its actin-binding domain. Expert Opin Biol Ther. 2018. PMID 30063851 DOI 10.1080/14712598.2018.1478961 Cell work on the parent protein. One of the three references submitted with the nomination
  16. Nguyen J, Verma S, Vuong VT, Queener H, Coulson-Thomas VJ, Gesteira TF. Engineered Tandem Thymosin Peptide Promotes Corneal Wound Healing. Invest Ophthalmol Vis Sci. 2025. PMID 41235866 DOI 10.1167/iovs.66.14.31 An engineered dual-domain molecule, distinct from both TB-500 and the parent protein
  17. Mendias CL, Awan TM. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. Sports Med. 2026. PMID 41966639 DOI 10.1007/s40279-026-02437-0
  18. Mayfield CK, Bolia IK, Feingold CL, Lin EH, Liu JN, Rick Hatch GF, Gamradt SC, Weber AE. Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians. Am J Sports Med. 2026. PMID 41476424 DOI 10.1177/03635465251357593
  19. Rahman OF, Lee SJ, Seeds WA. Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions. J Am Acad Orthop Surg Glob Res Rev. 2026. PMID 41490200 DOI 10.5435/JAAOSGlobal-D-25-00236
  20. US Food and Drug Administration. TB-500 (free base) and TB-500 acetate. Briefing document for the Pharmacy Compounding Advisory Committee, dated 15 May 2026, 41 pages, downloaded with a browser user agent and read in full on 9 August 2026 with the page count checked against the file. Carries the identity data, the nomination history, the marketed-claims inventory, the acetylation caveat, the FAERS and complaint-system searches, and the agency's proposal against adding either form to the 503A Bulks List. FDA advisory committee materials. 2026. Briefing document
  21. US Food and Drug Administration. July 23, 2026 Meeting of the Pharmacy Compounding Advisory Committee: FDA Presentations. 149 pages, page count checked against the file, read on 9 August 2026. The TB-500 evaluation runs from deck page 89 to deck page 118. Numbering inside that section restarts, so its slide 19 is deck page 107 and carries the effectiveness conclusion, its slide 21 is deck page 109 and carries the adverse event search with its footnote, and its slide 26 carries the WADA class. The companion deck for 24 July contains no TB-500 content. FDA advisory committee materials. 2026. FDA presentations
  22. US Food and Drug Administration. Questions for PCAC regarding whether FDA should include certain bulk drug substances on the 503A Bulks List, Pharmacy Compounding Advisory Committee, 23 and 24 July 2026. 2 pages, read in full. Item 3 of the 23 July afternoon session is TB-500-related bulk drug substances, on two voting questions covering the free base and the acetate. FDA advisory committee materials. 2026. Voting questions
  23. Office of the Federal Register. Pharmacy Compounding Advisory Committee; Notice of Meeting; Establishment of a Public Docket; Request for Comments. Bulk Drug Substances Nominated for Inclusion on the Section 503A Bulk Drug Substances List. Document 2026-07361, published 16 April 2026, Docket No. FDA-2025-N-6895. Its chart of evaluated uses records wound healing for TB-500 free base and TB-500 acetate. Federal Register. 2026. Notice of meeting
  24. US Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. The category 2 table carries the row Thymosin beta-4, fragment (LKKTETQ), also known as TB-500, with the immunogenicity and aggregation rationale and the statement that FDA has not identified any human exposure data for drug products containing the fragment. Page content current 22 April 2026, read 9 August 2026. FDA human drug compounding. 2026. Category 2 record
  25. Hudson Biotech. A Phase 1/2, Randomized, Double-Blind, Placebo-Controlled, Sequential Dose-Escalation Study of TB-500 (Thymosin Beta 4 17-23 Fragment) in Adults With Stable Atherosclerotic Cardiovascular Disease. Registry record read in full through the ClinicalTrials.gov API v2 on 9 August 2026: recruiting, actual start 5 February 2026, first posted 23 March 2026, 80 participants estimated, no results posted. Its registered brief summary begins: this fictional study is an example of a ClinicalTrials.gov-style record. ClinicalTrials.gov, NCT07487363. 2026. Registry record
  26. US National Library of Medicine, ClinicalTrials.gov. Registry searches run through API v2 on 9 August 2026. A term search for thymosin beta 4 returned 18 records, of which 17 registered the parent protein or a recombinant version of it, across dry eye, neurotrophic keratopathy, venous stasis ulcers, pressure ulcers, epidermolysis bullosa, corneal wounds in diabetes and acute myocardial infarction, and none in tendon, muscle or ligament. A sponsor search for Hudson Biotech returned 8 records, all recruiting, all first posted between 27 February and 1 April 2026, all single-site at Peking University Shenzhen Hospital, three of which state in their own registered text that they are example records. ClinicalTrials.gov. 2026. Registry searches
  27. ReGenTree, LLC. Assessment of the Safety and Efficacy of RGN-259 Ophthalmic Solutions in Dry Eye (ARISE-2). Registry record with posted results, read through the ClinicalTrials.gov API v2 on 9 August 2026: phase 3, 601 participants actual, completed March 2018. Both primary endpoints are change from baseline at day 29 on scales where a higher score is worse; ocular discomfort moved plus 0.07 against minus 0.04 on placebo and corneal fluorescein staining plus 0.07 against minus 0.01. No statistical test is posted alongside them. ClinicalTrials.gov, NCT02974907. 2018. Posted results
  28. World Anti-Doping Agency. The 2026 Prohibited List, World Anti-Doping Code International Standard, effective 1 January 2026. Class S2, peptide hormones, growth factors, related substances and mimetics, is prohibited at all times and its heading states that all prohibited substances in the class are non-Specified Substances. On page 8, class S2.3, growth factors and growth factor modulators, carries the entry Thymosin-ß4 and its derivatives e.g. TB-500. Read back from the final English document, 26 pages, retained off-site: the address below serves a zero-byte response to automated requests and is recorded as such in this repository's source ledger. WADA. 2026. Prohibited List
  29. National Center for Biotechnology Information. TYB4_HUMAN, Thymosin beta-4, accession P62328. Protein record read on 9 August 2026: a 44 residue precursor, MSDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES, whose annotated mature chain runs residues 2 to 44 and gives the 43 residue protein. Counting from the first serine of that mature chain, residues 17 to 23 are LKKTETQ. NCBI Protein. 2026. Protein record