Peptide

TB-500 (Thymosin Beta-4)

A 43-amino-acid peptide concentrated in platelets; it sequesters actin and promotes cell migration, angiogenesis, and modulation of inflammation. Approved only for investigational ophthalmic uses; the rest is "off-label" use.

Regulatory status

In clinical trials

FDA (U.S.): Not approved. For TB-500 (LKKTETQ fragment) the FDA noted possible immunogenicity and impurities and a lack of human exposure data (compounding proposal withdrawn). Full-length thymosin beta-4 as eye drops (RGN-259) has been studied in dry eye and neurotrophic keratitis trials, without approval.

EMA (EU): Not approved.

How to take it

No validated systemic human regimen. Clinical trials formulated as eye drops for the cornea (RGN-259). For systemic (subcutaneous) use there is no clinically established dose.

Safety

Safe in ophthalmic phase 1 up to 25 µg/kg. For systemic use there are no solid human data. Prohibited by WADA.

Effect by goal · level of evidence

Corneal repair and dry eye

improves Moderate phase 2 (A)

Corneal benefit (phase 2)

Phase 2 trials in the cornea: improves epithelialization and reduces severe dry eye pain. The only indication with quality human evidence.

View the study (phase 2) →

Joint repair

no clear effect Low review (A)

No human data

2026 review of peptides in sports medicine: there are no human trials showing that TB-500 repairs joints, tendons, or muscles. The evidence comes from animals and testimonials.

View the study (review) →

Information, not medical advice. Scientific evidence reflects the quality of the studies.