TB-500 Fragment
TB-500 (FRAG) · LKKTETQ
Short active fragment of thymosin beta-4 intended to retain the healing motif with faster clearance.
Key takeaways
- Short fragment of thymosin beta-4 centered on the LKKTETQ actin-binding motif.
- No direct human or animal studies of the fragment itself; all data is on the parent protein.
- Plotter half-life (~1 hour) and bioavailability are research estimates, not measurements.
- Vendor TB-500 products have historically contained this fragment instead of full-length Tβ4.
Reported dosing protocols
Protocols reported in research literature and clinic/community use — informational context, not a dosing recommendation.
| Use case | Dose | Route | Frequency | Duration |
|---|---|---|---|---|
| Soft-tissue repair (community) | 100–500 mcg | SubQ | 1–2× daily | 2–6 weeks |
Pharmacokinetic summary
- Model tier
- Simple (t½ + F, Tmax estimated)
- Half-life
- 58 min
- Bioavailability
- 50%
- Typical dose
- 0.1–0.5 mg
Frequently asked questions
Is TB-500 Fragment the same thing as TB-500?
Not quite. TB-500 is marketed as synthetic thymosin beta-4, a 43-amino-acid protein, while this fragment is just the short LKKTETQ-containing active motif. Because many vendor TB-500 products actually contained the fragment, the two names get used interchangeably, which is why COA verification matters.
Does the fragment work as well as full-length thymosin beta-4?
Unknown. The fragment retains the actin-binding region, but no study has compared the fragment against the full protein head-to-head in animals, let alone humans. Any claim of equivalence is assumption.
Why would anyone choose the fragment over TB-500?
The theory is cheaper synthesis and faster clearance while keeping the repair signaling. In practice the choice usually comes down to what the supplier actually stocks, since many products labeled TB-500 were this fragment all along.
References
- Estimated — Active sub-fragment of thymosin beta-4; shorter acting.
- Xing et al., Front Endocrinol 2021 — progress on the function and application of thymosin β4 — Review of the parent protein's repair biology, including the actin-binding motif the fragment is built around.
Related compounds
BPC-157
Gastric-derived peptide widely used off-label for tendon, ligament, and gut healing research.
TB-500 (Thymosin Beta-4)
Synthetic version of thymosin beta-4 involved in tissue repair, angiogenesis, and recovery.
ARA-290 (Cibinetide)
Peptide analog of the erythropoietin helix B region studied for neuropathy and tissue protection.
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