The traceable evidence consists of analytical, cell, rat, and equine work on the seven-amino-acid fragment.
Why this matters
Research depth describes how large and mature the overall record is. It does not tell you whether the results were positive.
Compound library
N-acetylated thymosin beta-4 heptapeptide fragment
TB-500
Not approved
TB-500 is a synthetic seven-amino-acid fragment of thymosin beta-4. It is not the full 43-amino-acid molecule. No human TB-500 studies were located, and human thymosin beta-4 findings should not be transferred to this fragment.
Laboratory studyAnimal studyMechanistic rationaleNo direct evidence located
Built by the community
Help strengthen the TB-500 experience record
Every structured report adds useful context about research setup, outcomes, and unwanted effects as the community dataset grows.
Publicly anonymous by default. Your account keeps reports editable and helps reduce duplicate submissions.Educational research record—not medical advice. Evidence reviewed through July 25, 2026. Peer-reviewed findings, regulatory labeling, sponsor-reported topline results, and unreported registered trials are labeled separately.
Research at a glance
TB-500 in 60 seconds
Depth and confidence summarize the research record—not effectiveness, safety, or a recommendation.
No human exposure, pharmacokinetic, safety, or efficacy study of verified TB-500 was located.
Why this matters
Confidence describes how reliable and consistent the conclusions are. It can be high for one outcome and low for another.
Why this matters
The strongest evidence type shows what the best-supported conclusions are actually based on.
Why this matters
Human findings are more directly relevant than animal or laboratory results, but they still apply only to the populations and outcomes studied.
Route-specific record
What changes by administration method
Route studiedSubcutaneous TB-500 free base in equine anti-doping research
Schedules studiedProtocol-defined single animal administration with serial plasma and urine sampling
Amounts studiedSpecies-specific equine research exposure only; no human amount established
Why this matters
These are exposures used in cited research for a specific route and population—not a suggested amount.
Half-lifeHuman SubQ pharmacokinetics and half-life are not established
Why this matters
Half-life describes how long it takes the measured amount in the body to fall by half. It is not a dosing recommendation.
Route evidenceAnimal detection and metabolism evidence, not human efficacy research
Why this matters
Evidence can change by administration method. Findings from one route should not automatically be applied to another.
Evidence boundary: Detectability and metabolites in horses do not establish tissue repair, a human amount, safety, or equivalence to full-length thymosin beta-4. Amounts shown describe cited research exposure—not a dosage recommendation.
Practical starting point
Why people research it
Common goals and questions—not recommendations or promises of benefit.
- Wound and injury healingPreclinical only
- Tendon and muscle recoveryPreclinical only
- Cell migration and repairPreclinical only
- Human recovery benefitsNot demonstrated
The overview, studies, and source ledger below explain what supports each label—and where the evidence stops.
The short version
What is TB-500?
TB-500 is a synthetic seven-amino-acid fragment of thymosin beta-4. It is not the full 43-amino-acid molecule. No human TB-500 studies were located, and human thymosin beta-4 findings should not be transferred to this fragment.
No human studies locatedCurrent development stage
3Peer-reviewed sources
0Topline source releases
How it is designed to work
- Contains thymosin beta-4 residues 17-23
- Proposed actin-binding-region activity — not clinically established
- Metabolism to shorter acetylated peptides
Studied research areas
Evidence checked through July 25, 2026
Includes FDA's May 2026 evidence review, the July 23 PCAC vote, the 2024 metabolism and fibroblast study, equine detection research, analytical identity literature, and the 2026 WADA list. Final FDA action was not located by the cutoff.
What the evidence says
What we know—and what we’re still learning
What we know
None located. FDA found no clinical study or human exposure data for TB-500 free base or acetate by any route.
Why this matters
This is the strongest supported conclusion in the current human evidence—not a summary of every claim made about the compound.
What we’re still learning
Whether TB-500 has any clinically meaningful human effect, how it behaves in people, repeated-exposure safety, and whether a labeled material is actually the stated free base or acetate.
Why this matters
Keeping the main uncertainty visible prevents an early or promising finding from looking more settled than it is.
The evidence story
How the research changed over time
Importance shows how much an item changes the evidence story. Quality shows how much confidence the design deserves. A strong negative study can score highly on both.
Why this matters
Importance and quality answer different questions. A rigorous study can be highly important even when it challenges a popular claim.
Simultaneous quantification of TB-500 and its metabolites in in-vitro experiments and rats
TB-500 was broken down into shorter acetylated peptides. Parent TB-500 did not improve fibroblast scratch-wound closure at the tested concentration; one shorter metabolite, Ac-LKKTE, showed activity.
In-vitro incubations and rat urine collection through 72 hours
Doping control analysis of TB-500 in equine urine and plasma by liquid chromatography-mass spectrometry
The parent peptide and multiple C-terminally shortened metabolites were detected in equine plasma and urine.
Plasma and urine sampling over hours after administration
Administration and handling
What official research does—and does not—provide
A compounding nomination is not dosing guidance
A withdrawn nomination described a lyophilized injectable for subcutaneous or intramuscular use. FDA found no human study using either route and no approved dose, schedule, injection site, or reconstitution procedure. Nomination details and animal protocols are not consumer instructions.
Bulk-material notes are form-specific, not consumer instructions
FDA reported supplier-level bulk storage observations for free base and acetate, while emphasizing that peptide stability depends on formulation, manufacturing, impurities, aggregation, temperature, light, and moisture. There is no FDA-approved finished product, reconstitution method, beyond-use period, or universal procedure.
Primary-source ledger
Trace every major statement
Primary source
Primary sourceJuly 23, 2026 PCAC official webcast and TB-500 vote
2026-07-23
Primary source
Primary sourceFDA evaluation of TB-500 free base and TB-500 acetate for the 503A Bulks List
2026-07-21
Primary source
Primary source2026 World Anti-Doping Code International Standard Prohibited List
2026-01-01
Primary source
Primary sourceSimultaneous quantification of TB-500 and its metabolites in in-vitro experiments and rats
2024-03-15 · PMID 38382158 · DOI 10.1016/j.jchromb.2024.124033
Primary source
Primary sourceDoping control analysis of TB-500 in equine urine and plasma by liquid chromatography-mass spectrometry
2012-11-23 · PMID 23084823 · DOI 10.1016/j.chroma.2012.09.043
Primary source
Primary sourceSynthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500
2012-09-07 · PMID 22962027 · DOI 10.1002/dta.1402