Recovery · Research Phase
Thymosin Beta-4 Fragment (TB4-Frag)
No lawful US pathway
01 · Overview
Thymosin Beta-4 fragments are short active segments of the 43-amino acid protein thymosin beta-4 (PMID 20179146). The best studied are the N-terminal tetrapeptide Ac-SDKP, which generally blocks inflammation and reduces fibrosis, and the seven-amino acid actin-binding sequence LKKTETQ (amino acids 17 to 23), which promotes angiogenesis, wound healing, and cell migration (PMID 20179146).
The acetylated 17-23 fragment has been identified in the product sold as TB-500 (PMID 22962027).
02 · Research summary & key findings
In rodents, Ac-SDKP reduced inflammation and fibrosis in a bleomycin model of lung fibrosis (PMID 27029074) and improved functional recovery after traumatic brain injury (PMID 28245754), and reviews describe organ-protective effects in heart, kidney, and brain injury models (PMID 29990624). The synthetic LKKTETQ peptide promoted dermal wound repair in aged mice comparable to full-length thymosin beta-4 (PMID 12581423). These findings come from animal and cell studies; no controlled human trials of thymosin beta-4 fragments as therapies have been published.
03 · Regulatory status
Thymosin Beta-4 Fragment (TB4-Frag) is in the research phase with limited clinical data in humans. Current evidence is primarily derived from preclinical (animal or in vitro) studies.
No lawful pathway today
Thymosin Beta-4 Fragment (TB4-Frag) is not FDA-approved and does not currently have a lawful prescription or compounding pathway in the United States, so we do not sell it and will not book a consultation for it. That can change: in 2026 FDA began reviewing several peptides for compounding. If you are working on the goal it is studied for, a licensed clinician can tell you what is lawfully available, which may be something else.
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Looking for a lawful, clinician-prescribed option for injury recovery and tissue repair?
Thymosin Beta-4 Fragment (TB4-Frag) is a research compound, is not FDA-approved, and has no lawful US compounding pathway, so we do not offer it and no clinician we work with will prescribe it. Products sold online as “research chemicals” are not made or tested to the standards required of medicines. If you are working on injury recovery and tissue repair, a licensed clinician can tell you at a free consultation whether an FDA-approved or lawfully compounded treatment fits you, or whether nothing does.
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04 · Administration routes
- Subcutaneous injection
- Topical
References
- [1]Thymosin beta 4 and a synthetic peptide containing its actin-binding domain promote dermal wound repair in db/db diabetic mice and in aged mice Wound Repair Regen, 2003. PMID 12581423
- [2]Biological activities of thymosin beta4 defined by active sites in short peptide sequences FASEB J, 2010. PMID 20179146
- [3]Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential Drug Test Anal, 2012. PMID 22962027
- [4]Preventive and therapeutic effects of thymosin β4 N-terminal fragment Ac-SDKP in the bleomycin model of pulmonary fibrosis Oncotarget, 2016. PMID 27029074
- [5]Treatment of traumatic brain injury in rats with N-acetyl-seryl-aspartyl-lysyl-proline J Neurosurg, 2017. PMID 28245754
- [6]The anti-inflammatory peptide Ac-SDKP: Synthesis, role in ACE inhibition, and its therapeutic potential in hypertension and cardiovascular diseases Pharmacol Res, 2018. PMID 29990624
Primary literature
- PubMed: "Thymosin Beta-4 Fragment"
Peer-reviewed literature indexed by the National Library of Medicine.
- ClinicalTrials.gov: "Thymosin Beta-4 Fragment"
Registered interventional and observational studies, including status and phase.
- PubChem: "Thymosin Beta-4 Fragment"
Chemical structure, molecular properties, and bioactivity data.
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Disclaimer: This information is provided for educational and research purposes only. It is not intended as medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting any peptide therapy. The Peptide Association does not endorse or recommend any specific treatment protocol. See our editorial policy for how this content is produced and reviewed. Clinicians: join the network.