TB-500 / Thymosin Beta-4
Tβ4 · also listed as “Thymosin Beta”
Actin-binding peptide; full-length Tβ4 has phase 2 data in eye and wound healing. TB-500 fragments have none.
Not FDA-approved. Not approved. WADA-prohibited. FDA Category 2 bulk-substance listing for compounding. This page describes research and public discussion; it is not a recommendation to use.
Overview
Thymosin beta-4 is a naturally occurring 43-amino-acid protein that regulates cell migration. RegeneRx tested full-length Tβ4 in dry eye, neurotrophic keratitis, and wound healing. ‘TB-500’ sold online is typically a synthetic fragment (Ac-LKKTETQ) with no human trial data.
Mechanism of action
Sequesters G-actin, promoting cell migration, angiogenesis, and reduced inflammation at injury sites.
Benefits & evidence ratings
Dosing
Doses show what has been studied or discussed — not guidance. Always follow your prescriber.
| Source | Dose | Frequency | Duration | Route |
|---|---|---|---|---|
Ophthalmic trials (RGN-259) B Human clinical data | 0.1% eye drops | Several times daily | Weeks | Topical ocular |
Online / clinic protocols D Anecdotal / community Not derived from controlled human trials. Reported for transparency, not recommendation. | 2–2.5 mg loading, then maintenance | 2× weekly | 4–6 weeks | Subcutaneous |
Clinical trials & studies
- Phase 32015–2019Thymosin β4 ophthalmic solution for dry eye (phase 2/3)
Improvements in some sign/symptom endpoints.
- Review2012Thymosin β4: a multi-functional regenerative peptide (Review)
Overview of preclinical mechanisms.
Safety
Side effects
- Injection-site reactions
- Fatigue, headache (anecdotal)
- Theoretical tumor-promoting angiogenesis
Contraindications
- Active cancer
- Pregnancy
- Competitive sport
Interactions
- Unknown
Long-term safety
Unknown for systemic injected use.
Regulatory status
Unapproved / research
Not approved. WADA-prohibited. FDA Category 2 bulk-substance listing for compounding.
FAQ
Commonly discussed alongside
Listing a combination does not mean it has been studied or is safe.