TB-500
TB-500 (Thymosin Beta-4 acetate) is a synthetic 43-amino acid peptide derived from the naturally occurring thymosin beta-4 protein, which plays crucial roles in cellular migration, angiogenesis, and tissue regeneration. Originally identified in the thymus gland, thymosin beta-4 is one of the most abundant intracellular proteins in mammalian cells and serves as a critical regulator of actin polymerization and cellular motility.
This synthetic peptide has gained considerable attention in regenerative medicine due to its demonstrated ability to promote wound healing, reduce inflammation, and enhance tissue repair across multiple organ systems in preclinical models. TB-500 exhibits unique properties in promoting angiogenesis, cellular migration, and tissue remodeling through its primary mechanism of actin regulation, making it a subject of intensive research into wound healing, cardiovascular repair, and musculoskeletal injuries.
Overview
TB-500 demonstrates remarkable resistance to proteolytic degradation and maintains activity across various physiological pH ranges, which may support its bioavailability. The peptide exhibits high systemic bioavailability via subcutaneous injection and distributes widely to tissues with high metabolic activity and injury sites.
Chemical structure & Properties
- Molecular Formula: C212H350N56O78S
- Molecular Weight: 4,963 Da
- Sequence: 43 amino acids with N-terminal acetylation
- Half-life: Approximately 2.5-3 hours following subcutaneous administration
- Stability: Stable at room temperature in lyophilized form, requires refrigeration when reconstituted
Mechanism of Action
TB-500 exerts its therapeutic effects through multiple interconnected cellular and molecular mechanisms:
Areas Investigated in
the Research Literature
Current Clinical Evidence
Safety Profile and Considerations
Regulatory Status and Legal Considerations
Regulatory information current as of 28 August 2026. This is a summary, not legal or medical advice, and status can change.
FDA Status
- Classification: Previously listed as Category 2. Nominated but withdrawn as of April 22, 2026
- Approval Status: Not approved for human therapeutic use in any indication
- Compounding: A July 23, 2026 FDA advisory committee recommended TB-500 for the 503A bulk drug substances list; the recommendation is non-binding and final FDA rulemaking remains pending.
- Regulatory Position: Insufficient evidence for safety and efficacy determination
WADA Status
- Classification: Prohibited under S2, peptide hormones/growth factors. Thymosin-beta4 and derivatives such as TB-500 are named.
- Athletic Use: Banned in competitive sports and subject to anti-doping penalties
- Testing: Detectable in anti-doping screening protocols and enforcement testing
Legal Availability
- Commercial Status: Not legally available as FDA-approved prescription medication
- Market Presence: Available through research chemical suppliers without regulatory oversight
- Quality Control: No regulatory oversight for purity, potency, or sterility standards
- Clinical Use: Limited to research institutions and experimental protocols under appropriate oversight
Conclusion
What the evidence supports
TB-500 is a synthetic fragment related to thymosin beta-4 studied in animal and cell-culture models for effects on tissue repair, cell migration and inflammation through actin regulation. Those results have not been carried into controlled human trials; there is no human efficacy data, no standardized dosing and no long-term safety data. TB-500 is not FDA approved for any therapeutic use and is prohibited under WADA; a July 2026 advisory-committee recommendation to add it to the 503A bulk drug substances list is non-binding and final FDA rulemaking remains pending. This page summarizes the published research and nothing further.
TB-500 SCIENTIFIC
DATA SUMMARY
About this library
This library is published for education. It summarizes published research on compounds studied in this field. Many have no approved medical use, and several cannot lawfully be compounded in the United States. The presence of a page here does not mean Paragon offers that compound. Nothing on these pages is an offer to treat.
This page is general education about a compound studied in this field. Nothing here is medical advice, a recommendation, or an offer to prescribe or supply. A page appearing in this library does not mean Paragon Sports Medicine offers that compound.
Disclaimer: This information is provided for educational purposes only and does not constitute medical advice. TB-500 is not approved by the FDA for human therapeutic use. Healthcare providers and patients should consult current regulatory guidelines and conduct thorough risk-benefit analyses before considering any peptide therapy.
Statements on this page have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Many peptides described here are not FDA approved for the uses discussed, and some cannot lawfully be compounded in the United States. Nothing on this page is medical advice or a recommendation for any individual. Whether any therapy is appropriate depends on your history, your laboratory results, and a clinical evaluation. Individual results vary. This page is published for education. Use of this site does not create a physician-patient relationship.