TB-500 and thymosin beta-4: a naming problem worth understanding first
A peptide named after a protein it is a fragment of, with a research literature that mostly belongs to the full protein rather than to the fragment. Sorting that out first makes everything else on the subject easier to read.
Regulatory status. Research compound — no FDA approval. Not for human use label. That is the app’s own field, reproduced here rather than summarised. It means no regulator has reviewed a manufacturer’s evidence for identity, purity, potency or safety in people for this compound, so nothing below is a marketing claim about a product you can buy.
Purity, identity and concentration are therefore unverified by anyone but whoever made the vial. The storage rule in the fact box below is general practice for this formulation rather than a specification for a particular product: General handling practice for this formulation. Your supplier’s own insert or COA overrides anything here.
This page names no vendor, no clinic and no testing service, and there is no discount code anywhere on this site — the moment a page like this recommends where to buy, it stops being information.
- Also known as
- Thymosin Beta-4
- Class
- Peptide
- Regulatory status
- Research compound — no FDA approval. Not for human use label.
- Modelled half-life
- 2 days — estimated half-life, limited human PK data
- Time to peak
- 4 h
- Formulation
- Aqueous (reconstituted powder)
- Before mixing
- Sealed powder tolerates room temperature in transit, but keep it refrigerated at 2–8 °C (36–46 °F) for anything beyond a few weeks, or frozen for months. Keep it dark — the carton it shipped in is doing a job.
- After mixing
- Once reconstituted with bacteriostatic water: refrigerate at 2–8 °C and use within about 28 days. The benzyl alcohol in bacteriostatic water is what buys that window — plain sterile water has no preservative, so a vial mixed with it should be treated as one sitting only. Kits are usually ten vials: only the one you mixed is on that 28-day clock — the sealed ones keep their own, much longer shelf life, so store them as powder, not as solution.
- What ruins it
- Do not freeze a reconstituted vial. Repeated freeze–thaw is one of the more reliable ways to degrade a peptide.
- Handling caveat
- General handling practice for this formulation. Your supplier’s own insert or COA overrides anything here.
The fragment and the protein are not interchangeable
Thymosin beta-4 is a 43-amino-acid protein found in most cells and in high concentration in platelets and wound fluid. Its main established function is binding monomeric actin, which makes it a regulator of the cytoskeleton and therefore of cell migration — the process by which cells move into a wound. That role is not in dispute; it is basic cell biology.
TB-500 as sold is generally a short synthetic peptide corresponding to the actin-binding region of that protein, not the protein itself. The two are routinely discussed as the same thing, including in most of the material written about it, and they are not. A fragment can retain some activity of its parent and lose the rest, and the studies people cite for TB-500 are usually studies of full-length thymosin beta-4.
This is not a pedantic distinction. Established clinical use Full-length thymosin beta-4 has been through genuine clinical development — formulated as an eye drop, it reached late-stage trials for neurotrophic keratopathy and dry eye disease. Those trials tell you something about a 43-residue protein applied topically to the cornea. They tell you very little about a fragment injected subcutaneously for a tendon.
What is actually known about the injected fragment
Animal-only or theoretical The musculoskeletal and cardiac findings that motivate its use come from animal work: accelerated wound closure, effects on cardiac repair after experimental infarction, and improved recovery in soft-tissue injury models. Mechanism proposals centre on actin sequestration promoting cell migration and on angiogenesis. As with most research peptides, the animal literature is more consistent than it is large, and it is not human evidence.
The app models a 48-hour half-life and flags it as an estimate — published human pharmacokinetic data is limited or absent. Two days is long for a peptide of this size and is the basis for the twice-weekly and weekly schedules described in the app's rows. Since the figure is inferred rather than measured, so is any accumulation or clearance number derived from it.
The app's own drawbacks list flags a preliminary cancer concern from animal studies, and that deserves to be stated plainly rather than buried: a compound whose proposed mechanism includes promoting cell migration and blood-vessel formation raises a theoretical question about a person with an undetected malignancy. Theoretical is the right word — there is no human evidence either way — and it is exactly the kind of question that belongs with a clinician who knows someone's history and screening status.
Sourcing, and why identity is the first problem
There is no approved product, so what is in a vial is whatever the manufacturer put there. For this compound the naming confusion makes that worse than usual: a vial labelled TB-500 could contain the short fragment, something closer to the full protein, a different fragment, or a degraded mixture, and none of those is distinguishable without analysis. This site names no vendor and no testing service, and it never will.
The peptide ships lyophilised and becomes a refrigerated, time-limited solution once reconstituted; the storage rule in the fact box is the app's own with its handling caveat attached. The reconstitution calculator handles the arithmetic of getting from a vial to a syringe volume, which is the one part of this that is not uncertain.
Anyone using this or considering it should be having the conversation with a clinician who knows their history — particularly the screening question above — and anything that feels wrong while using it is a reason to stop and ask rather than to work through it.
The curve, the accumulation ratio and the peak-to-trough figures have a page of their own: TB-500 half-life and steady state.
The dosing rows the app records
Animal-only or theoretical Reproduced from the app’s reference so you can see what it holds, not as a recommendation. Which row applies to a particular person, if any, is a clinical decision this page does not make — and rows describing supraphysiological or post-cycle use are filtered out before this table is built, so what you see here is a subset.
| Label | Amount | Route and frequency | Duration recorded |
|---|---|---|---|
| Loading | 2-2.5mg twice weekly | SubQ or IM | 4-6 week loading phase |
| Maintenance | 2-2.5mg once weekly | SubQ | Ongoing as needed |
What the app monitors alongside it
The panel below is the app’s own monitoring note for TB-500, verbatim. None of the analytes it names has a page here yet.
- Monitoring panel
- No specific labs. General health panel annually.
Drawbacks and risks the app records
From the app's own entry. The cancer item is preliminary and animal-derived, and it is the one worth raising with a clinician rather than weighing alone.
- Limited human trial data
- Some cancer concern in animal studies (preliminary)
- Quality sourcing critical
- Not approved for human use
- Relatively expensive
Interaction rules that name TB-500
From the app’s interaction data, filtered so no rule naming a compound this site does not publish appears. Not exhaustive, and not a safety clearance: a combination that is not listed is one nobody has documented here, which is not the same as one that is fine. The combination checker has the rest.
Gold Standard Injury Recovery Combination
BPC-157 and TB-500 are synergistic — BPC-157 acts locally on tissue repair mechanisms while TB-500 promotes systemic cell migration and actin upregulation. Together they represent the most comprehensive peptide approach to injury recovery.
What to watch: No specific labs. Monitor healing progress and injection sites.
Questions people actually ask
Is TB-500 the same as thymosin beta-4?
Not usually. Thymosin beta-4 is a 43-residue protein; TB-500 as sold is generally a short synthetic peptide from its actin-binding region. Most of the research cited for TB-500 was done on the full protein. Treating results from one as results for the other is the single most common error in writing about this compound.
Why is it so often paired with BPC-157?
Because the two are described as acting on different parts of tissue repair — one on cell migration, the other on angiogenesis and growth-factor signalling — so the pairing is a mechanistic argument rather than a tested combination. It is community practice with a plausible rationale and no trial behind it. The blend calculator covers the shared-vial arithmetic.
What does the estimated half-life mean for the dosing schedule?
That the schedule is built on an inferred number. Twice-weekly and weekly intervals follow from a two-day half-life, and if the real figure is materially different then so is the accumulation. The half-life page carries that caveat on every number it prints.
Is there any human trial data for the injected form?
Not for the fragment in musculoskeletal use. The clinical development that exists is for full-length thymosin beta-4 in ophthalmic and cardiac indications, by a different route.
Where the load-bearing numbers come from
Named rather than linked. Publisher URLs move, and a citation that resolves to a 404 two years from now is worse than one you can search for by name — every entry below is findable from the title and year alone.
- Thymosin beta-4 actin binding and cell migration
- Established cell-biology literature on beta-thymosins
- Clinical development of full-length thymosin beta-4
- Ophthalmic trials of a thymosin beta-4 formulation for neurotrophic keratopathy and dry eye disease, reported from 2015 onward
- Animal repair findings
- Rodent wound-healing and cardiac-repair models; not human evidence
- Estimated half-life
- app.html’s TL_PK entry, flagged est: limited or absent human pharmacokinetic data
When the compound's identity and half-life are both uncertain, your own record of what you did and when is the only firm data point. TherapyLog keeps it.
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