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TB-500

Also known as: Thymosin Beta-4 Fragment, Tβ4

FDA Banned (Category B)

Molecular Formula

C38 H68 N10 O14

Molecular Weight

846.98–889.02 Da

Half-Life

~2.5–3 hours (subcutaneous)

Sequence

Ac-LKKTETQ

Clinical Applications & Evidence

Mechanism of Action

The peptide primarily functions by sequestering globular actin (G-actin) to regulate the dynamic equilibrium of the cellular cytoskeleton, preventing premature polymerization into filamentous actin (F-actin). This mechanism maintains cellular plasticity, promoting the rapid migration of fibroblasts, keratinocytes, and endothelial cells to injury sites. Concurrently, it stimulates angiogenesis via the upregulation of Vascular Endothelial Growth Factor (VEGF) and exerts downstream cytoprotective and anti-fibrotic effects through the targeted modulation of nuclear factor-kappa B (NF-κB) inflammatory signaling pathways.

Investigated Uses

  • Muscle and tendon injury repair
  • Cardiac tissue repair post-infarction
  • Corneal and dermal wound healing
  • Reducing chronic inflammation
  • Hair regrowth (early research)
Early Clinical / Animal Models

Regulatory & Safety Status

FDA Status

FDA Banned (Category B)

WADA / Athletic Status

Prohibited in Competition

Known Side Effects

Head rushLethargyInjection site discomfort

Contraindications

  • Active cancer
  • Pregnancy
  • Recent head injuries

Drug Interactions

  • Potential synergistic or adverse interactions with anticoagulant therapies
  • Unpredictable adverse reactions from heavy metal or microbial contamination in unregulated grey-market formulations
  • Potential downregulation of endogenous thymosin peptide production

Citations & Clinical Trials

BSCG TB-500: Status, Risks, and Bans in Sport and Military GlobalRPH BPC-157 and TB-500: Background, Indications, Efficacy, and Safety FDA Safety and Regulatory Status of Bulk Drug Substances CCES Canadian Anti-Doping Program CCES Decisions ClinicalTrials.gov A Phase 3, Multi-Center, Randomized Clinical Study of RGN-259