TB5
Synthetic fragment of thymosin beta-4 (Tβ4). Studies of full-length thymosin β4 (not the TB-500 fragment) reported effects on tissue repair, cell migration and inflammation; TB-500 itself has no published human trials.
Regulatory status (as of Sept 2026)
Not FDA-approved. Removed from 503A Category 2 on April 15, 2026. PCAC recommended for the 503A Bulks List (advisory); awaiting FDA rulemaking; not lawfully compoundable under 503A as of Sept 17, 2026. PCAC vote: 8–6–1 (yes–no–abstain), July 23, 2026.
See the FDA peptide regulatory tracker · Read our July 27, 2026 dispatch on the FDA PCAC peptide vote9 studies referenced · Last reviewed Oct 1, 2026 · Reviewed by The Peptide Dispatch Editorial Team · How we research & label content
TB-500 is a compound studied only in animals and lab experiments so far. Synthetic fragment of thymosin beta-4 (Tβ4).
| Half-life | Not established in published research |
|---|---|
| How it's given in studies | Subcutaneous injection |
| Research stage | Preclinical (animal) |
| Dosing | Published research: All cited human data are for full-length thymosin β4 given IV at 42-1260 mg, single dose or daily for 14… detailsAll cited human data are for full-length thymosin β4 given i.v. at 42-1260 mg, single dose or daily for 14 days, n=40 healthy volunteers (Ruff 2010). Tβ4 was given topically or i.p. in rats (Malinda 1999). No published study doses TB-500 (the fragment) in humans.Community-reportedCommunity-reported: 2–5 mg per week, subcutaneous injection |
Published-research dosing is what was given in the cited studies (species and units as reported). Community-reported dosing is what users describe, not from clinical studies. Neither is a recommendation. Not medical advice.
Where each point comes from: Clinicalhuman trials and FDA labels Lab / animalrodent, cell and ex vivo studies Community-reporteduser experience and commonly used protocols, not from clinical studies
In plain terms: It is a fragment of thymosin beta-4; studies of the full protein suggest roles in cell movement and healing. Proposed mechanism, from studies of full-length thymosin β4 rather than TB-500 itself: actin binding, promotion of cell migration, and anti-inflammatory activity. In a rat full-thickness wound model, thymosin β4 increased re-epithelialisation (Malinda 1999).
How to read this: Each item below is an effect observed in research subjects in the cited studies — think of Dexter, our stand-in research subject. These are findings from the literature, not results you should expect, and not medical advice.
Community-reportedUsers have reported doses of 2–5 mg per week (subcutaneous injection). This is not a recommendation.
Side effects reported in studies are listed separately below.
Community reports are anecdotal, vary widely in product quality and purity, and are not medical advice. Talk to a licensed provider.
TB-500 is a synthetic fragment of the naturally occurring 43-amino acid peptide thymosin beta-4 (Tβ4). Full-length Tβ4 is found in virtually all human and animal cells, and studies of full-length Tβ4 (not the TB-500 fragment) have linked it to new blood vessel formation, muscle fiber formation, and cell migration and differentiation. Full-length Tβ4 is the major monomeric actin-sequestering molecule, regulating actin, a cytoskeletal protein involved in cell migration. Full-length Tβ4 has been studied in animal models of wound healing, cardiac injury and tissue regeneration, and intravenous and ophthalmic forms of full-length Tβ4 have been tested in human trials. TB-500 itself has no published human trials or pharmacokinetic data.
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Molecular Weight: 4,982 Da (full peptide) | Active fragment LKKTETQ: 846.97 g/mol
Molecular Formula: C212H350N56O78S (full) | Active fragment: C36H66N10O13
Structure Details: 43 amino acids with N-terminal acetylation. Contains central actin-binding domain (residues 17-23: LKKTETQ) surrounded by two alpha helices. The active region is the actin-binding motif essential for G-actin sequestration.
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| Peptide | Half-Life | Route | Research Status |
|---|---|---|---|
| TB-500 | No published PK data found | Subcutaneous injection | Preclinical (animal) |
| ARA-290 (Cibinetide) | No published PK data found | Subcutaneous injection, Intravenous | Phase 2 |
| BPC-157 | Elimination t1/2 < 30 min (rats and beagle dogs, IV and IM); IM bioavailability ~14-19% rats, 45-51% dogs | Subcutaneous injection | Preclinical (animal) |
| Copper Peptide AHK-Cu | Topical (not systemically relevant) | Topical | In vitro only |
| GHK-Cu | No published PK data found | Subcutaneous or topical | Cosmetic/topical |
Values reflect figures reported in published research. Compare any peptides side-by-side →
This peptide belongs to the Healing category. View All Healing Peptides
Immune
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Dosing, half-life figures, and mechanism descriptions on this page are compiled from peer-reviewed published research, with the species and study type stated where reported. Figures labeled “Dosing used in published research” describe what was given in those studies and do not constitute dosing recommendations for any human use. Each cited paper is listed with DOI and PubMed links in the References section above. Found an error? Contact us.