Compound reference
TB-500
Also known as Thymosin Beta-4 Fragment
A synthetic acetylated fragment of thymosin β4 (Ac-LKKTETQ) studied for tissue repair. Its evidence is preclinical, its first human trial — a safety study — only began in 2026, and it is unapproved and prohibited in sport.
- CAS
- 885340-08-9
- Sequence
- Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln (thymosin β4, 17–23)
- Half-life
- Not established in humans
Research peptide; not FDA-approved as a medicine.
Mode of action
TB-500 is a synthetic, N-acetylated heptapeptide — Ac-LKKTETQ — corresponding to residues 17–23 of thymosin β4, the actin-binding region of that 43-amino-acid protein rather than the whole molecule. Thymosin β4 itself has a broad preclinical profile: it binds actin monomers to drive cell migration, supports angiogenesis, limits programmed cell death through ILK–Akt signalling, dampens inflammation, and improved myocyte survival and cardiac function after induced injury in mice. TB-500 is proposed to reproduce the tissue-repair part of that profile through the shared actin-binding sequence.
Two caveats sit on top of that story. First, most of this biology is established for full-length thymosin β4 — a larger, distinct molecule — not the fragment sold as TB-500. Second, a 2024 metabolite study found that TB-500 is cleared quickly and that only its metabolite Ac-LKKTE showed meaningful wound-healing activity in fibroblasts, which suggests the intact peptide may act as a carrier while a breakdown product does the work. All of this is cell-culture and animal evidence.
Main intended effect
TB-500 is studied as a systemic tissue-repair and cell-migration peptide — wound healing and soft-tissue or musculoskeletal recovery — and, more recently, for vascular and endothelial effects. It is investigational, with no defined or approved indication.
Areas of interest
Interest centres on soft-tissue and musculoskeletal recovery, where TB-500 is frequently paired with BPC-157 in gray-market "healing" combinations, and the public conversation has run well ahead of the data. A newer thread is cardiovascular: the first registered human trial targets endothelial function in atherosclerotic disease, echoing thymosin β4's cardiac-repair signals in animals. Much of TB-500's perceived promise, though, is borrowed from the larger body of research on full-length thymosin β4 rather than earned by the fragment itself.
Evidence for intended effects
TB-500 sits near the thin end of the evidence spectrum, though that is starting to change. Until 2026 there were no registered controlled human trials at all. In February 2026 the first one began recruiting: a Phase 1/2 randomised, double-blind, placebo-controlled study (NCT07487363, sponsor Hudson Biotech) of subcutaneous TB-500 in adults with stable atherosclerotic cardiovascular disease. It is a safety and biomarker study — not an efficacy trial — and no results exist yet.
Everything else is preclinical or borrowed. The direct data are in vitro fibroblast wound-healing assays and rat pharmacokinetics, and much of the rationale is extrapolated from thymosin β4, a distinct and larger molecule whose own human testing has not gone past early-phase dermatology and eye-condition studies. A 2026 orthopaedic and sports-medicine review states plainly that human orthopaedic data are lacking. The closest treatment-context human datapoint is an uncontrolled retrospective knee-pain series in which BPC-157 was combined with thymosin β4 (not TB-500), with no placebo or blinding. Certainty for any human musculoskeletal benefit remains very low.
| Strand | What exists | Tier |
|---|---|---|
| Human trials | One Phase 1/2 safety + biomarker RCT in cardiovascular disease (recruiting) | Phase 1/2, safety only |
| Wound healing / cell migration | In vitro fibroblast assays + rat PK | Preclinical |
| Core mechanism | Extrapolated from thymosin β4 | Preclinical (different molecule) |
| Musculoskeletal efficacy | Uncontrolled combination case series (β4, not TB-500) | Very low / none |
Studied amounts (literature dosing context)
There is no established or approved human dose, and no published human pharmacokinetic data. The first human trial escalates subcutaneous TB-500 through sequential cohorts, but those amounts are a trial-internal protocol, not a recommendation. In rat studies the parent peptide is cleared quickly — a short-lived Ac-LK metabolite appears within hours. This page does not provide dosing guidance.
Safety and regulatory status
No human safety dataset exists yet; the new Phase 1/2 trial is designed to begin building one. One mechanistic concern is worth stating plainly: the angiogenic and tissue-growth pathways TB-500 engages overlap with scarring and tumour biology, so its long-term safety is genuinely unknown.
On regulation, TB-500 is prohibited in sport under the World Anti-Doping Code — a 2026 sports-medicine review lists it among banned substances. In 2023 the FDA issued a warning letter to a company selling TB-500 as a dietary supplement, stating that it is not a lawful dietary ingredient and is an unapproved new drug lacking the required safety and efficacy data. Health Canada lists TB-500 among online peptides it warns against injecting, noting that unauthorised products are not assessed for safety, quality, or purity. That last point matters especially here: products sold as "TB-500" vary in what they contain, and the name is often conflated with full-length thymosin β4.
Sources
Utilizing Developmentally Essential Secreted Peptides Such as Thymosin Beta-4 to Remind the Adult Organs of Their Embryonic State—New Directions in Anti-Aging Regenerative Therapies
Review by Maar and colleagues in Cells (May 2021; DOI 10.3390/cells10061343) on thymosin beta-4 (Tβ4), the 43-amino-acid secreted peptide from which TB-500 is derived. It describes Tβ4 binding actin monomers to influence cell migration and cytoskeletal dynamics, activating ILK-Akt signaling to limit myocardial cell death, and reactivating embryonic gene programs in adult tissue. Preclinical highlights include improved myocyte survival and cardiac function after coronary ligation in mice, epicardial thickening, and progenitor-cell activation, with additional wound-healing roles in brain, kidney, cornea, and skin. Human data are limited to early-phase dermatology trials reported as safe and well tolerated; no completed human cardiac trials are presented. The review concerns full-length Tβ4 rather than the TB-500 fragment specifically.
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
Preclinical analytical and pharmacological study (Rahaman et al., Journal of Chromatography B, 2024; DOI 10.1016/j.jchromb.2024.124033) developing a UHPLC-Q-Exactive Orbitrap MS/MS method to quantify TB-500 (Ac-LKKTETQ, the thymosin beta-4 17-23 fragment) and its metabolites in vitro and in rats. Three principal metabolites were characterised: Ac-LK as the primary short-term metabolite (peak 0–6 hours), Ac-LKK as a longer-lived metabolite (detectable to 72 hours), and Ac-LKKTE as the metabolite with notable biological activity. In fibroblast wound-healing assays the parent peptide and metabolites showed no cytotoxicity, but only Ac-LKKTE produced significant wound-healing activity — leading the authors to conclude that TB-500's reported wound-healing effects may be due to the metabolite Ac-LKKTE rather than to the intact parent peptide. Findings are from in vitro assays and rat pharmacokinetics; human in vivo efficacy has not been established.
Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians
Narrative review by Mayfield and colleagues in The American Journal of Sports Medicine (January 2026) surveying injectable peptides used in orthopaedic and sports-medicine contexts, including BPC-157, thymosin beta-4 (TB-4), and its fragment TB-500. The authors note that TB-4 and TB-500 promoted angiogenesis and tissue repair in preclinical models but that human orthopaedic data are lacking, and that both remain prohibited substances in sport. They conclude that current human clinical evidence does not support clinical use of these peptides for orthopaedic indications and call for rigorous trials before any clinical recommendation.
TB-500 (Thymosin Beta 4 17-23 Fragment) for Cardiovascular Biomarkers in Stable ASCVD (TB-500-CV-101)
Phase 1/2 randomized, double-blind, placebo-controlled, sequential dose-escalation study (NCT07487363; sponsor Hudson Biotech) of TB-500 — the thymosin beta-4 17-23 fragment — in an estimated 80 adults with stable atherosclerotic cardiovascular disease and endothelial dysfunction. Participants are randomized 3:1 (drug to placebo) across three sequential dose cohorts. The primary outcome is safety: incidence of treatment-emergent adverse events over 12 weeks and serious adverse events over 28 days, with cardiovascular biomarkers as secondary measures. The study began recruiting on February 5, 2026, with estimated primary completion in February 2027. It is the first registered controlled human trial of TB-500; as a safety and biomarker study it is not designed to establish efficacy, and no results are available.
Intra-Articular Injection of BPC 157 for Multiple Types of Knee Pain
Retrospective chart review (Lee and Padgett) of 17 patients (16 contactable at follow-up) given intra-articular BPC-157, either alone or combined with thymosin beta-4, for various types of knee pain in a primary-care setting in Orlando, Florida. Among those receiving BPC-157 alone, 11 of 12 (91.6%) reported significant improvement; the combined peptide group showed 75% improvement; overall, 14 of 16 patients (87.5%) reported pain relief. No placebo arm, blinding, or objective outcome measures were used, making results highly susceptible to placebo effect and reporting bias. The report is hypothesis-generating only and does not establish efficacy.
Can peptide injections help people recover from injuries? Here's what you need to know
Explainer in The Conversation (May 7, 2026) by Flynn McGuire, a physical medicine and rehabilitation resident at the University of Utah, on peptide injections marketed for injury recovery, focusing on BPC-157 and TB-500. The piece notes that BPC-157's human evidence is very thin — essentially one small, uncontrolled knee-pain series — and that TB-500's animal data come largely from full-length thymosin beta-4, a larger molecule whose findings may not transfer to the smaller fragment. It also flags that the tissue-growth pathways these peptides engage overlap with scarring and tumour biology. The overall stance is cautiously skeptical: without human trials, standardized dosing, verified product contents, or established safety, these remain unproven.
TB-500 for Injury Recovery: What the Research Actually Shows
Physician explainer (March 2026) by Dr. Jeffrey Peng, a board-certified sports-medicine physician, reviewing TB-500 for injury recovery. It summarizes the mechanisms shared with thymosin beta-4 — angiogenesis, anti-inflammatory effects, inhibition of programmed cell death, and support for cell migration — and emphasizes the gap between plausible biology and human evidence: Phase 1 safety appears acceptable and ophthalmology applications of thymosin beta-4 have shown benefit, but controlled musculoskeletal trials are absent. The author calls TB-500 biologically plausible and short-term safe but not proven effective for orthopaedic use, notes it lacks FDA approval and remains experimental, and cautions that commercial purity and dosing vary widely because products are sold as research compounds.
https://www.jeffreypengmd.com/post/tb-500-for-injury-recovery-what-the-research-actually-shows
FDA Warning Letter to Supplement Manufacturer Regarding TB-500
FDA warning letter (June 2023) issued to a company marketing TB-500 (thymosin beta-4 fragment) as a dietary supplement. The FDA states that TB-500 does not meet the statutory definition of a dietary ingredient and therefore cannot be lawfully marketed as a dietary supplement under the Federal Food, Drug, and Cosmetic Act. The letter further identifies TB-500 as an unapproved new drug lacking the safety and efficacy data required for drug approval. Cited violations include marketing an unapproved drug and making unlawful claims. The company was required to take corrective action to bring its products into compliance or cease distribution.
Think twice before injecting peptides bought online: unauthorized products can seriously harm you
Health Canada public safety advisory published April 9, 2026 warning consumers against injecting peptides purchased online. The advisory explicitly names numerous peptides commonly available through unregulated channels, including BPC-157, CJC-1295, GHK-Cu, Ipamorelin, Melanotan I and II, MOTS-c, SS-31, TB-500, and Retatrutide, among others. Health Canada confirms that peptides are generally regulated as prescription drugs in Canada and that unauthorized products have not been assessed for safety, efficacy, or quality. Identified risks include hormonal imbalance, blood sugar dysregulation, liver or kidney damage, blood clots, tumor growth, infections, and contaminants including heavy metals and bacteria. The advisory explicitly states that "For Research Use Only" labeling does not exempt a product from Canadian drug regulations, and that lawfully authorized Canadian drugs display an eight-digit Drug Identification Number (DIN).