The Pep Test Guide 2026
The Pep Test Guide 2026U.S. vendor guide
All compounds
Healing

TB-500

Also known as: Thymosin Beta-4, TB4

Thymosin beta-4 fragment with repair indications in preclinical studies.

TB-500

What is TB-500

TB-500 is a synthetic fragment of the body’s own protein thymosin beta-4 (Tβ4). Strictly speaking, TB-500 is not identical to native thymosin beta-4, but rather a market-established term for a particular active section of the molecule (often the sequence LKKTETQ, “actin-binding domain”). In practice, the terms TB-500 and thymosin beta-4 are used largely synonymously, even if this is not completely clean chemically.

Native thymosin beta-4 is a 43-amino acid peptide originally isolated from the thymus of calves (Low et al., 1981). It occurs in almost all human cells and is one of the most common intracellular peptides. Molecular weight of the native peptide: 4963 g/mol. CAS Tβ4: 77591-33-4.

Mechanism of action

Thymosin Beta-4 is primarily an actin-binding protein. It binds G-actin (monomeric actin) and thereby regulates the cytoskeleton dynamics. This results in several downstream effects.

First, TB-4 promotes cell migration. Injured tissues need immigrant cells for repair, and actin polymerisation is a prerequisite for migration. Secondly, Tβ4 stimulates angiogenesis, similar to BPC-157, probably via VEGF-mediated pathways.

Third, it has anti-inflammatory effects via inhibition of NF-κB activity. Fourth, it promotes the differentiation of stem cells in several tissues (endothelium, heart muscle, skin).

The combination of these effects explains the broad healing profile in preclinical studies.

Areas of application in research

  • Whereund healing: Skin wounds, diabetic ulcers, burns
  • Heart regeneration: Post-infarct models, reduction of scarring
  • tendon and ligament injuries: Repair and strength
  • Neuroprotection: Stroke models, multiple sclerosis models
  • Corneal healing: Topical application for corneal defects
  • Hair growth: Stem cell activation in hair follicles
  • Antibacterial activity: Whereund infection models

Study situation

The scientific basis of thymosin beta-4 is more extensive than many other peptides because the molecule has been researched since the 1980s and Tβ4 plays a role as a regulatory peptide in stem cell research.

Important works:

  • Goldstein et al. (Annals of the New York Academy of Sciences, 2007): Review on the function of Tβ4 in wound healing and tissue regeneration
  • Bock-Marquette et al. (Nature, 2004): Central study of Tβ4 in heart regeneration
  • Sosne et al. (Experimental Eye Research, 2010): Topical application in corneal healing
  • Phase 2 clinical trials of RGN-352 (Tβ4 formulation of RegeneRx): trials in patients with chronic pressure ulcers and epidermolysis bullosa, mixed results

What is clear: Tβ4 plays a real biological role in tissue regeneration and this is at least partially reproducible in clinical trials. What is unclear: optimal dosage in humans, whether the systemically administered TB-500 acts in a potency comparable to the body's own protein.

Mixing (reconstitution)

Typical vials: 2 mg, 5 mg, 10 mg lyophilisate. TB-500 vials are usually larger than BPC-157 vials because the standard doses are higher.

  • 5-mg Vial with 2 ml of bacteriostatic water → 2.5 mg/ml
  • 10 mg Vial with 2 ml → 5 mg/ml
  • 10 mg Vial with 5 ml → 2 mg/ml for finer dosage

Bacteriostatic water is preferred. After mixing cooling 2 to 8 degrees, stability about 4 weeks. Lyophilisateeeee stable at -20 degrees over years.

Dosage range (research data)

Preclinical studies and research protocols result in the following theoretical areas:

  • batch phase: 2 to 5 mg per week for 4 to 6 weeks
  • Maintenance phase: 2 mg every 1 to 2 weeks
  • Forms of administration: subcutaneous or intramuscular
  • Typical cycle duration: 6 to 12 weeks

These values come from research references and the self-application community, not approved clinical protocols.

Side effects

In controlled clinical trials using Tβ4 formulations (RGN-259 topical, RGN-352 systemic), the tolerability profile was good. Frequent side effects:

  • Temporary fatigue after injection
  • Local irritation at the injection site
  • Rarely: headache, nausea

Anecdotally, flu-like symptoms are reported in the first 1 to 2 days after initial doses, presumably immunologically mediated. The pro-angiogenic profile is a theoretical risk in active tumors. Long-term human safety is not established.

Half-Life and Pharmacokinetics

The plasma half-life is relatively short, in the range of 2 to 3 hours for the full Tβ4 molecule. The biological effect lasts longer, similar to BPC-157, because downstream processes (actin dynamics, cell migration) are slower than plasma clearance.

Forms of administration: subcutaneous, intramuscular, intravenous in studies. Topically effective for eye and skin indications. Oral bioavailability not established, probably low due to proteolytic degradation in the GI tract.

Frequent questions

What is the difference with BPC-157? BPC-157 primarily promotes angiogenesis and gastrointestinal healing. TB-500 primarily promotes cell migration and stem cell activation. Many users combine both.

How fast does TB-500 work? Animal studies show effects within days to 1 to 2 weeks. In humans, anecdotally similar, controlled data on the time of action are missing.

Is TB-500 the same as Thymosin Beta-4? Not quite. TB-500 is mostly a synthetic fragment that includes the active section. Native thymosin beta-4 is the complete 43-amino acid protein. In practice, the terms are often used synonymously.

Is TB-500 allowed for athletes? No. WADA has TB-500 on the prohibited list, category S2 (peptide hormones). Application in competitions is clearly prohibited.

How do I store TB-500 after mixing? Refrigerator, 2 to 8 degrees, dark, maximum 4 weeks. Protect against frost.

Legal status U.S.

As of 2026: TB-500 is not an approved medicine in Germany, Austria and Switzerland. It falls under the AMG in therapeutic use. Research-use-only distribution exists in a legal grey area, not intended for self-application.

WADA ban has been in place since 2011. For athletes, the use is prohibited. For own import, §73 AMG restrictions apply.

Related compounds

  • BPC-157Complementary healing peptide, often combined
  • GHK CuCopper peptide with regenerative effect
  • Thymosine alpha-1Immunomodulatory peptide from the thymus
  • IGF-1 LR3growth factor analogue
  • larazotideTight junction peptide for gut health

Note: All information is for research information only. These peptides are not approved as medicines in Germany. The contents do not replace medical advice. Application to humans is not legally covered in Germany.