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Thymosin Beta-4

Also known as Tβ4 · Thymosin β4 · RGN-259

Actin-sequestering peptide with clinical data in ophthalmic wound healing and preclinical tissue repair.

Tier B-Cmed–high riskintermediateWADA S2FDA Flagged
Tier B-C
Evidence
6-10 week phase
Protocol
med–high
Risk
topical
Route

WADA S2

This substance falls under WADA S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics). If you are subject to anti-doping rules, this category of substances is prohibited at all times.

FDA Safety Flag

The FDA has identified this substance as one that may present significant safety risks when used in compounding, including concerns about immunogenicity, impurity characterization, and/or insufficient safety information.

Evidence visual

Thymosin Beta-4 evidence and risk matrix

intermediate researcher fit

Evidence

Tier B-C

Risk

med high

Regulatory

investigational

WADA

S2

FDA

flagged

Route

topical

Mixed evidence profile. Useful for comparison, not a standalone protocol decision.

Overview

Thymosin beta-4 is a 43-amino-acid peptide involved in cell migration, angiogenesis, and tissue repair. Clinical ophthalmic studies using topical 0.1% formulations (RGN-259) report safety and improved epithelial healing in corneal disorders. Systemic claims have weaker clinical grounding. WADA classifies thymosin-β4 derivatives under growth factor modulators.

Decision path

Where Thymosin Beta-4 fits in the research path.

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2 related goals
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  2. 02

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  3. 03

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  4. 04

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Peptide research path

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Research Details

Mechanism of Action

Actin-sequestering protein with roles in cell migration, angiogenesis, and tissue repair across multiple active domains.

Administration Routes

topical, subcutaneous

Study Dose Range

Clinical ophthalmic: topical 0.1% formulation. Systemic dosing not well established in humans.

Expected Effects

Ophthalmic: improved corneal epithelial healing. Systemic: wound healing signals in preclinical models.

Dosing Timeline

Corneal healing studies: days to weeks; systemic repair claims are less well-timed.

Contraindications

Limited formal contraindication data.

Adverse Effects

Human ophthalmic safety reported as acceptable in trials; systemic safety requires caution.

Interaction Notes

Limited formal interaction studies; treat as unknown outside studied settings.

Cost at a glance

Typical cycle cost

$192.00

Estimated monthly

$96.00

Protocol style

6-10 week phase

Phase-based

Estimate confidence

High confidence

Assumes roughly 12 mg24 mg per cycle, using 1 tracked affiliated listing.

Reflects multi-week repair protocols instead of a one-month estimate.

Known Interactions

Caution

TB-500

TB-500 is often described as a thymosin beta-4 fragment/region; must confirm exact sequence and avoid mixing fragment vs full-length assumptions.

Caution

BPC-157

Commonly co-marketed; limited interaction evidence; treat as uncertain.

Frequently Compared

Compare top

BPC-157

Tier C

TB-500

Tier C

MGF E-domain

Tier C

Thymosin Alpha-1

Tier B

Information provided for educational and research reference only. Not medical advice. Not for diagnosing, treating, curing, or preventing disease. Products referenced are labeled Research Use Only (RUO) by vendors; not for human or veterinary use.

Sources and review notes

  1. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks - U.S. Food and Drug Administration - accessed 2026-05-15

    Used for FDA compounding-risk context and peptide safety flags.

  2. The Prohibited List - World Anti-Doping Agency - accessed 2026-05-15

    Used for athlete-facing WADA risk and peptide-class restrictions.

  3. Peptide therapeutics: current status and future directions - PubMed / Nature Reviews Drug Discovery - accessed 2026-05-15

    Used for broad peptide-therapeutics background and evidence framing.

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