Thymosin Beta-4: Discovery, mechanism, and clinical development
⚠️ Informational Purposes Only
This content is for educational and research purposes only. TB-500 is not FDA-approved for human use. Always consult qualified healthcare providers for medical decisions.
Pharmacokinetics
~7 day half-life
Origin
Thymus gland
FDA Status
Not approved
Thymosin Beta-4 (TB-4) was first isolated from the thymus gland in the 1960s by Dr. Allan Goldstein. TB-500 represents the synthetic version of the active fragment of this naturally occurring peptide. The compound has been studied for its role in cell migration, wound healing, and tissue repair mechanisms. Unlike its parent compound, TB-500 has not undergone the clinical development pathway required for pharmaceutical approval.
Research indicates TB-500 influences cellular processes through several pathways:
Discovery
Thymosin fraction 5 isolated from calf thymus by Goldstein and colleagues
TB-4 Sequenced
Complete amino acid sequence of Thymosin Beta-4 determined (43 amino acids)
Preclinical Research
Extensive animal studies on wound healing, cardiac repair, and tissue regeneration
Clinical Trials (Limited)
Phase I/II trials for dry eye, pressure ulcers, and cardiac indications. Development stalled.
The most advanced TB-4 clinical program was developed by RegeneRx for ophthalmic indications. RGN-259 (eye drops) completed Phase II trials for dry eye syndrome and neurotrophic keratitis. However, development progress has been limited, and no Phase III trials have been initiated as of 2025.
Source: RegeneRx SEC filings, ClinicalTrials.gov
FDA Status: TB-500 is not approved by the FDA for any indication. No Investigational New Drug (IND) applications are currently active for systemic TB-500 administration in humans.
WADA: Thymosin Beta-4 and its derivatives are prohibited at all times under section S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics) of the WADA Prohibited List. Athletes should be aware that TB-500 use would constitute an anti-doping violation.
Compounding: The FDA has issued warning letters to facilities compounding TB-500, citing lack of approved applications and concerns about manufacturing quality and sterility.
| Parameter | Available Data | Context |
|---|---|---|
| Half-life | ~7 days (estimated) | Based on animal models; human PK unknown |
| Distribution | Systemic | Not localized to injury sites |
| Metabolism | Proteolytic degradation | Susceptible to peptidases |
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