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PPepIndex

Evidence digest

What the research on TB-500 actually shows

Almost all literature cited for TB-500 concerns thymosin beta-4, the full parent protein — not the fragment sold under the TB-500 name. This distinction is the whole story for this compound. A vendor citing thymosin beta-4 research on a TB-500 product page is citing work about a different molecule, and the indexed literature contains no controlled human trial of the fragment as sold.

Updated 22 Jul 2026 · 6 studies indexed · 5 human · compound record

Studies indexed
6
Human evidence
5
Preclinical only
1

What is and is not established

What the literature supports

  • A preclinical literature exists for thymosin beta-4, the parent protein, across several rodent injury models.
  • A small number of early-phase human studies of the parent protein were conducted; none reached marketing approval.
  • The material sold as TB-500 is a synthetic fragment, not the parent protein.

What is NOT established

  • No controlled human trial of the TB-500 fragment as sold appears in the indexed literature.
  • Equivalence between the fragment and the parent protein is not established. Evidence about one is not evidence about the other, and vendor pages frequently conflate them.
  • No regulator has approved either the fragment or the parent protein for any indication.
  • No human safety or pharmacokinetic profile exists for the fragment.

Studies indexed

1 animal · 4 human — controlled trial · 1 case report
Each row links to that study's permalink, where every digest citing it is listed. Findings are reported as the paper reported them — an animal result is not restated as a human one.
StudyEvidence typeModelnWhat it reportedSource
Published work on thymosin beta-4, the parent protein of TB-500PubMed listingAnimalMultiple rodent injury modelsPlaceholder seed record. This literature concerns thymosin beta-4, the full parent protein — not the fragment sold as TB-500. Vendors frequently cite this body of work when listing TB-500; the two are not the same molecule, and evidence about one is not evidence about the other.Listing
Early-phase human work on thymosin beta-4PubMed listingHuman — controlled trialNot recordedPlaceholder seed record. A small number of early-phase human studies of the parent protein exist in the listed literature. None were carried through to marketing approval in any jurisdiction, and none concern the TB-500 fragment as sold.Listing
Malignant thymoma associated with T-cell lymphocytosis. A case report with immunophenotypic and gene rearrangement analysisArchives of pathology & laboratory medicine · 1993Case reportNot recordedPatients with malignant thymoma rarely may also have a peripheral T-cell lymphocytosis. "Lymphocyte spillover" from the thymus into the peripheral blood as well as a second, associated neoplasm (ie, T-cell chronic lymphocytic leukemia) are two hypotheses that have been proposed to explain this clinical phenomenon. We describe another patient with a lymphocyte-rich malignant thymoma associated with peripheral T-cell lymphocytosis. At the time of initial diagnosis, the patient'…PMID 8382915
Thymosins: structure, function and therapeutic applicationsThymus · 1984Human — controlled trialNot recordedUsing a partially purified preparation, thymosin fraction 5, we have documented that thymosin can correct many of the immunological deficiencies resulting from the lack of thymosin function in animal models and in humans. Ongoing studies indicate that there is a family of biologically active peptides within fraction 5 that act on T-cell subpopulations to maintain normal immunological reactivity. Several of these peptides have been purified to homogeneity. Two peptides, thymos…PMID 6087503
A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteersAnnals of the New York Academy of Sciences · 2010Human — controlled trialNot recordedSynthetic thymosin beta 4 (Tbeta4) may have a potential use in promoting myocardial cell survival during acute myocardial infarction. Four cohorts, with 10 healthy subjects each, were given a single intravenous dose of placebo or synthetic Tbeta4. Cohorts received ascending doses of either 42, 140, 420, or 1260 mg. Following safety review, subjects were given the same dose regimen daily for 14 days. Safety evaluations, incidence of Treatment-Emergent Adverse Events, and pharm…PMID 20536472
The effect of thymosin treatment of venous ulcersAnnals of the New York Academy of Sciences · 2010Human — controlled trialNot recordedVenous ulcers are responsible for about 70% of the chronic ulcers of the lower limbs. Standard of care includes compression, dressings, debridement of devitalized tissue, and infection control. Thymosin beta 4 (Tbeta4), a synthetic copy of the naturally occurring 43 amino-acid peptide, has been found to have wound healing and anti-inflammatory properties, and is thought to exert its therapeutic effect through promotion of keratinocyte and endothelial cell migration, increased…PMID 20536470

Regulatory status

WADAProhibited list

WADA Prohibited List — growth factors and peptide hormones (class S2)

Placeholder seed entry recording the source, not an event. The World Anti-Doping Agency publishes an annual Prohibited List; class S2 covers peptide hormones, growth factors, related substances and mimetics. Several compounds tracked in this index fall within that class or its catch-all clause. The list is revised annually and takes effect on 1 January. PepIndex records revisions affecting indexed compounds here.

IpamorelinCJC-1295TB-500

Vendors listing TB-500

The evidence above describes the published literature. What any individual vial contains is a separate question, answered by that vendor’s certificate records rather than by any study on this page.

How to read this page

This digest describes what published research exists and what it does not establish. It is not a recommendation, contains no dosing information or protocols, and makes no claim that any compound is safe or effective for any purpose. Material listed by indexed vendors is labeled for laboratory research use only.