TB-500
Thymosin Beta-4 fragment
TB-500 is a synthetic peptide sold as a fragment of thymosin beta-4, a naturally occurring actin-binding protein, and is most rigorously documented in doping-control chemistry rather than in therapeutic research.
Regulatory status: Not an approved drug anywhere and not a lawful dietary-supplement ingredient. Thymosin beta-4 and its analogues are prohibited in sport, and doping-control laboratories have published methods for detecting TB-500.
Default vial
5 mg
Default mix
2 mL
Reported range
2–2.5 mg loading, 2.5–5 mg maintenance
Draw (U-100)
100 u
Loading phase twice weekly for 4–6 weeks, then maintenance every 2–4 weeks.
What it is
- Marketed as a synthetic version of an active region of thymosin beta-4, a 43-amino-acid protein found in most tissues and in platelets.
- Thymosin beta-4 itself is a well-characterised, highly conserved actin-sequestering protein; the commercial 'TB-500' is not the same molecule.
- Peer-reviewed work on TB-500 specifically is dominated by analytical chemistry — detecting it in urine and plasma — rather than efficacy studies.
- Studied by injection in the contexts where it appears in the literature, largely equine doping control.
How it is described to act
- 1
Given by injection in the settings that have been studied, which are mostly veterinary doping-control experiments rather than therapeutic trials.
- 2
Researchers report that it becomes detectable in plasma and urine after administration in horses, indicating systemic distribution.
- 3
Any mechanism attributed to it is inferred from thymosin beta-4 biology — actin binding, cell migration, angiogenesis — not from TB-500-specific human studies.
- 4
The observed context in the literature is analytical detection; efficacy endpoints in people have not been published under this name.
What the research has looked at
Doping-control chemistry
- Researchers writing in the Journal of Chromatography A (2012) described an LC-MS method for detecting TB-500 in equine urine and plasma, developed because of interest in the compound as a performance or regenerative agent.
What is known about the parent protein
- Cell-biology literature attributes actin-binding and cell-motility roles to thymosin beta-4 itself. That is evidence about thymosin beta-4, not verified evidence about the product sold as TB-500.
Strength of evidence: Preclinical evidence only
No peer-reviewed human efficacy or safety studies of TB-500 itself were located; the citable science is either doping detection or research on the distinct parent protein.
What is published comes from cell and animal studies. Findings in those models frequently do not carry over to people.
Reported cautions and unknowns
- No controlled human safety data for TB-500 were located in the peer-reviewed literature.
- Its prohibited status in sport reflects regulatory concern about undisclosed physiological effects.
- Because products sold under this name are unregulated, their actual chemical identity and purity are not independently verified in the literature.
References
Handling this vial
- Lyophilized vials are generally stored at 2–8 °C and kept out of light; once reconstituted with bacteriostatic water they are refrigerated and commonly discarded after 28 days.
- Mix by aiming water down the vial wall and rolling gently — do not shake — and never re-freeze a reconstituted vial.
- Pep-Tidy cannot verify what is in your vial. Ask your supplier for a current Certificate of Analysis (HPLC/MS).
TB-500 questions people ask
How do you reconstitute TB-500?
A common starting point for a 5 mg vial of TB-500 is 2 mL of bacteriostatic water, which gives 2.5 mg per mL. Aim the water down the inside wall of the vial, let it dissolve on its own, and roll gently instead of shaking. Pep-Tidy's reconstitution calculator will recalculate the numbers for any other vial size or water volume you use.
How many units of TB-500 is one dose?
At 2.5 mg per mL, that works out to about 100 units on a U-100 insulin syringe for a 2500 mcg dose. Change the vial size, water volume, or target dose in the calculator and the syringe reading updates with it. This is arithmetic, not a dosing recommendation.
What dosing schedule is reported for TB-500?
Published and community sources describe 2–2.5 mg loading, 2.5–5 mg maintenance, subcutaneous, twice weekly, typically run 6 weeks on and 2 weeks off. These figures describe what has been reported, not what anyone should take — talk to a licensed clinician first.
How should TB-500 be stored?
Lyophilized TB-500 vials are generally kept at 2–8 °C and out of light. Once reconstituted with bacteriostatic water they are refrigerated and commonly discarded after about 28 days. Never re-freeze a reconstituted vial and never shake it.
Read this before you act on anything above
Everything on this page is a summary of what other people have published — it is not medical advice, not a recommendation, and not a dosing instruction. Reported dose ranges describe what appears in the literature or in community protocols, not what anyone should take. Talk to a licensed clinician before using any peptide.