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Recovery · Research Phase

TB-500 (Thymosin Beta-4)

Awaiting FDA decision

Talk to a clinician about your goal
Written by Peptide Association Editorial TeamLast reviewed Editorial policy

01 · Overview

Thymosin Beta-4 (Tβ4) is a 43-amino acid actin-sequestering protein involved in cell migration and tissue repair. Products sold as TB-500 have been found to contain a synthetic 7-amino acid Tβ4 fragment (Ac-LKKTETQ) rather than the full protein (PMID 22962027); clinical trials use full-length Tβ4, not TB-500.

In human corneal cells, Tβ4 suppressed NF-kB activation, suggesting anti-inflammatory activity (PMID 17254567).

02 · Research summary & key findings

Tβ4 and its LKKTETQ fragment accelerated wound repair in diabetic and aged mice (PMID 12581423). A Phase II dry eye trial of Tβ4 eye drops missed its primary endpoints but improved some secondary measures (PMID 26056426). In a 96-patient STEMI trial, recombinant Tβ4 did not significantly reduce overall infarct size versus placebo (PMID 41229390).

03 · Regulatory status

TB-500 (Thymosin Beta-4) is in the research phase with limited clinical data in humans. Current evidence is primarily derived from preclinical (animal or in vitro) studies.

TB-500 (Thymosin Beta-4) is not FDA-approved, and as of October 2026 FDA has not finalized whether pharmacies may compound it. Whether a pharmacy will compound it depends on the pharmacy and your state. 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.

04 · Administration routes

  • Subcutaneous injection

References

  1. [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. [2]Thymosin beta 4 suppression of corneal NFkappaB: a potential anti-inflammatory pathway Exp Eye Res, 2007. PMID 17254567
  3. [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. [4]Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment (CAE™) model Clin Ophthalmol, 2015. PMID 26056426
  5. [5]Recombinant human thymosin beta 4 improves ischemic cardiac dysfunction in mice and patients with acute ST-segment elevation myocardial infarction after reperfusion Cardiovasc Res, 2025. PMID 41229390

Primary literature

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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.