Peptide education
TB-500
Also known as: Thymosin beta-4 fragment · Tβ4 (17-23) — Synthetic fragment of thymosin beta-4
TB-500 is a synthetic peptide based on the actin-binding region of thymosin beta-4, a naturally occurring protein involved in cell migration and repair. Enthusiasm rests on animal models and veterinary use history.
Regulatory status
Not FDA-approved. Prohibited at all times by WADA for athletes.
What the evidence shows
Full-length thymosin beta-4 has early clinical work in wound and corneal healing; the TB-500 fragment sold online has essentially no published human trials. Sports-medicine claims are extrapolation.
Human evidence
None of substance for the TB-500 fragment specifically.
Animal & preclinical evidence
Cardiac, corneal, dermal, and muscle injury models, plus a long history of gray-market equine use.
Proposed mechanism
Binds G-actin and promotes cell migration, angiogenesis, and reduced inflammation in injury models — mechanisms characterized largely in vitro and in rodents.
Potential risks
- No human safety data for the fragment
- Cell-migration/angiogenesis pathways carry theoretical oncologic concern
- Universal anti-doping prohibition for competitive athletes
Contraindications
- Active or suspected malignancy
- Competitive athletes subject to anti-doping rules
- Pregnancy and breastfeeding
Common research endpoints
- Cell migration rate (in vitro)
- Cardiac remodeling markers (rodent)
- Wound closure (animal models)
Questions to ask a licensed clinician
- Is there any published human trial of the exact fragment being sold?
- What is my anti-doping exposure if I compete?
- What standard-of-care options exist for my injury first?
References
- Goldstein AL, Hannappel E, Sosne G, Kleinman HK (2012). Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opinion on Biological Therapy. SourceReview
- World Anti-Doping Agency (2024). The Prohibited List — S2 peptide hormones, growth factors and related substances. WADA. SourceAgency list
Related compounds
- BPC-157 — Preclinical-dominant
Related tools
Something incorrect on this page? Report a correction — safety-relevant issues are triaged within one business day.