TB-500 (Thymosin Beta-4 fragment)
Also known as: Ac-LKKTETQ, TB500
TB-500 (Thymosin Beta-4 fragment), also called Ac-LKKTETQ or TB500, is a thymosin β4 fragment in the Wound Healing / Cytoprotective class. TB-500 is a synthetic peptide corresponding to the actin-binding region of thymosin beta-4, usually the LKKTETQ heptapeptide or a short sequence containing it, rather than the full 43-amino-acid protein.
For research use only.
Key Facts
- CAS
- 77591-33-4
- Molecular Weight (MW)
- ~889 Da (heptapeptide fragment forms vary)
- Half-life
- Hours; not well defined for research fragments
- FDA status
- Not Approved
- Evidence level
- Insufficient Evidence
- Human dose established
- No
- Administration Route
- Not established in humans
- Frequency
- Not established in humans
- Last updated
- Sep 26, 2026
- Reviewed
- Aug 30, 2026
- Targets
- G-actinCell migration pathways
Vendor price snapshot
Each vendor counts once, at the median price per mg of its own listings; the typical range is the middle half of vendors. From public vendor listings collected between Dec 2025 and Oct 2026, so confirm the live price on the vendor site. Peptide Library does not sell peptides.
- Vendors listing this peptide
- 41
- Listed offers
- 103
- Median price per mg
- $6.42/mg
- Typical $5.05–$8.30/mg
Research summary
Usually sold as an acetylated thymosin-β4 actin-binding fragment (LKKTETQ), not full-length Tβ4. Not FDA-approved. Related to prohibited thymosin-β4 use in sport.
Peptide Library's TB-500 (Thymosin Beta-4 fragment) profile summarises 3 cited studies listed in the Science section, the compound's regulatory status, and research-protocol parameters reported for it. It is a research reference, not medical advice.
TB-500 (Thymosin Beta-4 fragment) dosage: no established human dose
TB-500 has no established human dosage. One interventional human trial is registered and still recruiting; it has published no results and does not disclose its dose. The substantial thymosin beta-4 literature is largely about the full 43-amino-acid protein, not the shorter 17-23 fragment sold as TB-500, so it cannot be read across as dosing evidence for this compound.
No established human dosage.
Human clinical evidence: None identified.
Preclinical research: There are roughly 600 indexed publications on thymosin beta-4, covering wound repair, cardiac and renal injury, and corneal healing, almost entirely in animal and cell models. Nearly all of that work uses the full-length 43-amino-acid protein. TB-500 is the shorter 17-23 actin-binding fragment, so this literature describes a related but different molecule and does not establish a dose, a route or an interval for TB-500 in humans.
Animal dosing is not converted into a human dose anywhere on this page. Where research figures appear below, they are reported as studied, not recommended.
| Human dosing established | No |
|---|---|
| Route | Not established in humans |
| Evidence level | Insufficient Evidence |
| Last reviewed | 2026-09-05 |
Human research reported
Doses as studied, one row per regimen. Different trials used different regimens; they are listed separately rather than averaged.
| Study / context | Population | Dose | Route | Frequency | Duration | Outcome studied | Source |
|---|---|---|---|---|---|---|---|
| NCT07487363 — phase 1/2, recruiting, no resultsClinical trial · Registered phase 1/2 placebo-controlled trial, recruiting | Adults with stable atherosclerotic cardiovascular disease (planned n=80) | Not disclosed | Not disclosed | — | — | Cardiovascular biomarkers | NCT07487363 — TB-500 (Thymosin Beta 4 17-23 Fragment) for Cardiovascular Biomarkers in Stable ASCVD |
Preclinical and analog research
Not human dosing evidence. Listed for completeness and never extrapolated to a human dose.
| Study / context | Population | Dose | Route | Frequency | Duration | Outcome studied | Source |
|---|---|---|---|---|---|---|---|
| Preclinical — thymosin beta-4 in kidney diseasePreclinical · Preclinical review of the full-length proteinStudied an analog, not TB-500 (Thymosin Beta-4 fragment) itself | Animal models | Model-specific; not convertible to a human dose | Varies by model | — | — | Renal injury and fibrosis | Thymosin beta 4: An emerging therapeutic candidate for kidney diseases. Peptides. 2026. |
Where sources disagree
- TB-500 and thymosin beta-4 are routinely treated as the same compound in vendor material and secondary sources. They are not: TB-500 is a seven-residue fragment of the 43-residue protein. Evidence generated with full-length thymosin beta-4 is not dosing evidence for TB-500, and this profile marks such rows as analog evidence.
- Loading-and-maintenance protocols in the 2–10 mg per week range are widely published for TB-500. No human trial has reported those doses, and no primary source for them could be identified.
Reconstitution
Common research vial sizes: 2 mg, 5 mg, 10 mg.
| Vial | Bacteriostatic water | Concentration | Per 0.01 mL |
|---|---|---|---|
| 5 mg | 2 mL | 2.5 mg/mL | 25 mcg per 0.01 mL |
| 10 mg | 2 mL | 5 mg/mL | 50 mcg per 0.01 mL |
These figures are arithmetic only — they convert a vial and a volume into a concentration. They are not a recommendation to take any dose.
Calculate reconstitution & dose →Handling & administration
- Reconstitution Guide
- Add 2–5 mL bacteriostatic water per vial as preferred concentration.
- Injection Sites
- AbdomenPeri-injury subQ
- Concentration Example
- 5 mg + 2 mL → 2.5 mg/mL
- Timing Notes
- Keep a consistent weekly schedule Prefer injectable forms; oral versions generally have low bioavailability and are not recommended. When stacking different classes, space injections by 15–30 minutes; do not mix in the same syringe unless verified compatible.
- Expected Onset
- 1–2 weeks
How to reconstitute TB-500 (Thymosin Beta-4 fragment)
- Check the vial size and diluent volume. The profile example for TB-500 (Thymosin Beta-4 fragment) is: Add 2–5 mL bacteriostatic water per vial as preferred concentration.
- Swab both vial stoppers and draw the bacteriostatic water into a sterile syringe.
- Add the water slowly down the inside wall of the peptide vial so it does not jet onto the powder, then swirl gently until the solution is clear. Do not shake.
- Record the resulting concentration: 5 mg + 2 mL → 2.5 mg/mL.
- Label the vial with the date and concentration, refrigerate it (see Storage & stability below), and use the calculator preset to convert a dose in mcg into syringe units.
Open the peptide calculator with the TB-500 (Thymosin Beta-4 fragment) preset →
Sequence & molecular data
| Molecular formula | C38H68N10O14 |
|---|---|
| Molecular weight | ~889 Da (heptapeptide fragment forms vary) |
| CAS number | 77591-33-4 |
| Half-life | Hours; not well defined for research fragments |
| Appearance | White lyophilized powder |
| Formulation | Lyophilized Powder |
| PubChem CID | 62707662 |
| FDA UNII | QHK6Z47GTG |
Identifiers link to the public PubChem, FDA Substance Registration (UNII), ChEMBL and DrugBank records for the same entity.
Science
Mechanism of Action
TB-500 is a synthetic peptide corresponding to the actin-binding region of thymosin beta-4, usually the LKKTETQ heptapeptide or a short sequence containing it, rather than the full 43-amino-acid protein. That distinction matters: the fragment reproduces the actin-sequestering motif and the cell migration and angiogenic effects attributed to it in preclinical models, but it cannot reproduce activities of the intact protein that depend on regions outside that motif. Commercial material sold under this name varies in exactly which sequence it contains. It is unapproved, has no controlled human efficacy data, and is prohibited in sport.
Origin
Synthetic Tβ4 fragment.
Targets
Regulatory & research status
TB-500 (Thymosin Beta-4 fragment) is not an FDA-approved product. It is sold for laboratory research and has no approved medical use.
| FDA status | Not Approved |
|---|---|
| Availability | Research-Only |
| WADA (sport) | Banned in Sport |
| Library classification | Research-Only |
Benefits
TB-500 (Thymosin Beta-4 fragment) side effects
TB-500 (Thymosin Beta-4 fragment) has no controlled human safety data. The effects below are reported, not established, and absence from the list is not evidence of safety.
Side Effects
- Injection reactions
- Unknown long-term safety
Contraindications
- Stop if significant inflammation or allergic reaction occurs
Stacking
Common stacking partners
Combinations that include TB-500 (Thymosin Beta-4 fragment), with the proposed rationale, an evidence grade and what is not established, are catalogued in the peptide stacks directory.
Storage & stability
Lyophilized (freeze-dried) peptide powder is far more stable than the reconstituted solution. Keep sealed vials cold, dry and away from light; long-term storage is typically frozen, with short-term refrigeration for vials in use.
Once reconstituted in bacteriostatic water, keep the solution refrigerated, avoid repeated freeze–thaw cycles and agitation, and label the vial with the reconstitution date and concentration. Discard any solution that turns cloudy or shows particulates.
Degradation rates differ by sequence: peptides containing methionine, cysteine, asparagine or glutamine are more prone to oxidation and deamidation, so shelf life after reconstitution is compound-specific rather than universal.
Read the full guide: how to store peptides before and after reconstitution →
Source: Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharm Res. 2010;27(4):544–575. (PMID 20143256). General guidance for research handling; not product-specific instructions.
TB-500 (Thymosin Beta-4 fragment): frequently asked questions
What is TB-500 (Thymosin Beta-4 fragment)?
Usually sold as an acetylated thymosin-β4 actin-binding fragment (LKKTETQ), not full-length Tβ4. Not FDA-approved. Related to prohibited thymosin-β4 use in sport. TB-500 is a synthetic peptide corresponding to the actin-binding region of thymosin beta-4, usually the LKKTETQ heptapeptide or a short sequence containing it, rather than the full 43-amino-acid protein. That distinction matters: the fragment reproduces the actin-sequestering motif and the cell migration and angiogenic effects attributed to it in preclinical models, but it cannot reproduce activities of the intact protein that depend on regions outside that motif.
What are the side effects of TB-500 (Thymosin Beta-4 fragment)?
TB-500 (Thymosin Beta-4 fragment) has no controlled human safety data, so its side-effect profile is not well established. Effects recorded on this profile include injection reactions. Cautions recorded on this profile: stop if significant inflammation or allergic reaction occurs. It is on the WADA Prohibited List for athletes. This is reference information, not medical advice.
How does TB-500 (Thymosin Beta-4 fragment) work?
TB-500 is a synthetic peptide corresponding to the actin-binding region of thymosin beta-4, usually the LKKTETQ heptapeptide or a short sequence containing it, rather than the full 43-amino-acid protein. That distinction matters: the fragment reproduces the actin-sequestering motif and the cell migration and angiogenic effects attributed to it in preclinical models, but it cannot reproduce activities of the intact protein that depend on regions outside that motif.
Is TB-500 (Thymosin Beta-4 fragment) FDA approved?
No. TB-500 (Thymosin Beta-4 fragment) is not approved by the FDA for any indication and is categorised as research-only. It has not been reviewed for safety or efficacy as a medicine, and published research should be read as investigation rather than established use.
What is the half-life of TB-500 (Thymosin Beta-4 fragment)?
Reported half-life for TB-500 (Thymosin Beta-4 fragment) is Hours; not well defined for research fragments. Half-life describes how long the compound persists in circulation, not how long any effect lasts, and published figures vary with route of administration, formulation and the population studied.
Is TB-500 (Thymosin Beta-4 fragment) banned in sport?
TB-500 (Thymosin Beta-4 fragment) is recorded here as prohibited in sport. Athletes subject to anti-doping rules should check the current WADA Prohibited List directly, since it is revised annually and classifications change.
What peptides are similar to TB-500 (Thymosin Beta-4 fragment)?
Compounds most often compared with TB-500 (Thymosin Beta-4 fragment) include BPC-157, Pentadeca Arginate, Thymosin β4 (Tβ4) and GHK-Cu (Copper Peptide). They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ.
How long does TB-500 (Thymosin Beta-4 fragment) take to show effects in research protocols?
The research protocol on this profile lists an expected onset of 1–2 weeks. This is a protocol note describing when studies and researchers report observing changes, not a measured clinical outcome, and it varies with the model, dose and endpoint studied.
Where is TB-500 (Thymosin Beta-4 fragment) administered in research protocols?
Research protocols on this profile use subcutaneous administration, with recorded sites including abdomen, peri-injury subq. Site rotation and sterile technique are standard practice in the research literature; this describes protocol conditions and is not guidance for use.
References
- WADA Prohibited List 2026External reference
- Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance — Sports Med, 2026External reference
- Peptide Supplements and Their Therapeutic Applications in Sports Medicine — Am J Sports Med, 2026External reference
- Equine Doping Controls of Thymosin β 4: A Population Study and Strategy for Misuse Detection — Drug Test Anal, 2025External reference
Related research, comparisons & guides
- BPC-157 Dosage: What the Research Literature Actually Reports
- GLOW Peptide Blend: What Is Actually in the Vial
- KLOW vs GLOW: What Adding KPV Changes, and What It Does Not
- Thymosin Alpha-1: An Approved Immune Drug in Much of the World
- TB-500 Dosage: What the Fragment Is, and What the Numbers Rest On
- The Wolverine Stack: What It Is and Where the Name Came From
- BPC-157 Benefits: Sorting the Claims From the Evidence
- BPC-157 Side Effects: The Honest Answer Is That Nobody Has Looked
- KLOW Peptide Dosage: What the Blend Contains and How It Is Measured
- Peptide vs Protein: Where the Line Is Drawn
- BPC-157 Capsules: Does Oral BPC-157 Survive Digestion?
- KLOW Peptide Blend: GLOW Plus KPV, and What That Addition Changes
- BPC-157 and TB-500: Why Blended Vials Break the Usual Math
- BPC-157
- Thymosin Beta-4
- Muscle and recovery peptidesCategory
- Peptide stacks: combinations by research goalStacks
- Peptide dosage chart: dose, route and frequencyCategory
- Peptide calculator with the TB-500 (Thymosin Beta-4 fragment) preset
- How to store peptides before and after reconstitution
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Compiled by Peptide Library Editorial · Reviewed Aug 30, 2026 · Updated Sep 26, 2026 · Version 6
This TB-500 (Thymosin Beta-4 fragment) profile is compiled from published literature (3 cited studies linked above), public regulatory records and chemical registries. It describes what research reports; it is not medical advice, and nothing here is a dosing recommendation for humans. Peptide Library does not sell peptides. Editorial policy · How profiles are compiled · Report an error
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