TB-500 sits in a different regulatory bucket from almost every other compound in this buyer's guide series. It's not FDA-approved. It's not on the Category 2 list (which would at least flag it as a compound under regulatory scrutiny). It's not scheduled. It's an unscheduled research peptide, which means there's no formal quality oversight on any product sold under that name, and no compounding pharmacy lane to access it. Zero human clinical trials have been published on TB-500 specifically as of 2026 (WADA, 2025).
That doesn't mean TB-500 is uninteresting. The parent compound, thymosin beta-4 (Tβ4), has a Phase II cardiac surgery trial running and a real preclinical track record. TB-500 is a synthetic fragment of Tβ4, the actin-sequestering region, residues 17–23. But the regulatory void means quality is entirely on the buyer to verify. There are no institutional checks anywhere in the supply chain.
Key Takeaways
- —TB-500 is unscheduled and gray market. No FDA scheduling, no compounding pathway, no institutional QA. Every check falls on you.
- —Zero published human clinical trials exist for TB-500 specifically. The Phase II cardiac data is for full-length Tβ4 (Thymosin Beta-4), not the fragment.
- —TB-500 has been on the WADA Prohibited List since 2011. Any tested athlete is categorically banned from use.
- —Before running anything, read the TB-500 research profile on Next Pep for the mechanism, evidence review, and dosing context.
TB-500 is a synthetic peptide matching residues 17–23 of thymosin beta-4, the actin-sequestering domain that drives Tβ4's cell migration and tissue repair activity. Molecular weight is roughly 889 Da and the sequence in most commercial lots is Ac-LKKTETQ-NH₂. The CAS number you'll see most often is 77591-33-4.
This split from full-length Tβ4 (MW ~4,963 Da) matters when you're checking quality. A vendor selling "TB-500" should be selling the 7-amino-acid fragment at 889 Da. Not a longer fragment, not the full protein. Mass spec at 889 Da is your identity confirmation.
The case for the fragment over the full protein comes from studies showing the actin-sequestering domain alone reproduces Tβ4's cell migration activity. The fragment is also far cheaper to synthesise at research scale. Whether the full-length protein would beat the fragment in any specific use case isn't established.
There's no regulatory floor on TB-500 quality, so third-party testing is your only protection. The same framework that applies to every research peptide applies here, with two TB-500-specific additions.
HPLC purity ≥98%. Standard floor for research-grade lyo powder. At ≥99% you're getting elite material suitable for binding and cell migration assays. 95–98% is fine for most preclinical work.
Mass spec at ~889 Da. This is the TB-500-specific identity check. The measured mass should be roughly 889.04 Da for the acetylated, amidated form. If the COA shows anything near 4,963 Da (full Tβ4), the vendor is mislabelling the product.
Independent lab with verifiable report ID. Not vendor-internal testing. An accredited, named third-party lab, with a report number you can pull up directly on their server. Janoshik and Finnrick are the names you'll see most often in the community for this. Verifying the report eliminates the bulk of bunk vendors immediately.
Endotoxin (LAL) assay. TB-500 protocols typically involve subq pins, so endotoxin burden actually matters. LPS contamination at research-relevant doses can cause local inflammation and systemic reactions that aren't the peptide doing anything. Ask whether endotoxin testing was run and ask for the result.
Lyo powder, stored at -20°C. TB-500 in solution degrades much faster than the lyo form. Properly lyophilised TB-500 should be white to off-white with no yellowing. Discolouration means oxidation or sloppy processing, and you should reject the lot.
The evidence picture for TB-500 is the most important thing to understand before you order anything. The mechanism story is genuinely compelling — actin regulation, cell migration, cardiac regeneration — and the preclinical record is consistent. The human data picture is bleak.
There are zero published human clinical trials on TB-500 specifically. The Phase II cardiac trial that exists used full-length Thymosin Beta-4, not TB-500. They aren't the same molecule. Whether the fragment reproduces the full protein's cardiac regeneration in humans isn't established (PMC literature, 2024). The musculoskeletal protocols people are running are extrapolated from animal studies and clinician reports, not controlled human trials.
That doesn't make the preclinical work worthless. It's the reason TB-500 still gets serious research attention. But anyone buying it is working off a much weaker evidence base than compounds like sermorelin (FDA-approved history, human IGF-1 data) or tirzepatide (FDA-approved, 72-week RCT).
The TB-500 research profile on Next Pep covers the actin regulation mechanism, the cardiac progenitor cell data, the Tβ4 fragment vs. full protein distinction, dosing protocols extrapolated from the Phase II precedent, and the honest evidence summary. Start there.
WADA has banned TB-500 since 2011 under the Prohibited List category for peptide hormones and related substances. Detection methods for TB-500 metabolites in urine and plasma have been specifically developed and validated (WADA scientific research, 2025). Any tested athlete, pro or amateur, should treat TB-500 as detectable and prohibited, full stop.
The Next Pep comparison tool puts TB-500 next to BPC-157 on mechanism, half-life, and dosing. Plenty of people run them together — the Wolverine stack — because the mechanisms don't overlap. BPC-157 drives angiogenesis and TB-500 drives cell migration, so they cover different pieces of the repair cascade. Knowing what each one actually does before ordering either is worth the twenty minutes the comparison takes. The peptide library covers both compounds in full, with molecular data, human trial summaries, and regulatory status. That's your objective research foundation before you start vetting any vendor. Once you've settled on a protocol, the dosing calculator converts vial mg to draw volume and syringe units.
No. Related, but different. Thymosin beta-4 (Tβ4) is the full 43-amino-acid endogenous protein (MW ~4,963 Da). TB-500 is a synthetic 7-amino-acid fragment matching residues 17–23 of Tβ4 (MW ~889 Da), specifically the actin-sequestering domain. Most published research on cardiac regeneration and tissue repair used full-length Tβ4, not the fragment. Whether TB-500 reproduces all of the parent protein's activity in humans isn't established.
Pull the COA and check that mass spec shows roughly 889 Da. If the COA shows a MW near 4,963 Da, you're looking at full-length Tβ4 (different compound) or the COA is mislabelled. Confirm HPLC purity ≥98%. Verify the report ID directly on the issuing lab's server — Janoshik and Finnrick are the standard names. If any of those steps fail, walk away from that vendor.
TB-500 isn't a scheduled controlled substance in the US, so personal possession isn't a criminal offence. It's also not FDA-approved, not on the Category 2 list (which limits compounding), and not regulated as a pharmaceutical anywhere. WADA prohibits it for tested athletes. It sits in a complete gray-market zone: legal to possess, unregulated for quality, banned in sport.
The Wolverine stack — BPC-157 plus TB-500 — is the most common pairing in musculoskeletal protocols. The case for it is mechanism complementarity. BPC-157 drives angiogenesis and GH receptor upregulation, TB-500 drives cell migration via actin regulation. No published study has examined the combination directly. There's no known contraindication. The combination hasn't been formally studied in humans.
This article is for research and educational purposes only. TB-500 is not approved for human therapeutic use in any jurisdiction. WADA prohibits its use in competitive sport.
Research Disclaimer. All content on Next Pep is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Consult a licensed healthcare professional before considering any peptide protocol.
CJC-1295 with DAC has a 6-8 DAY half-life; Modified GRF (1-29) clears in ~30 minutes. Same modified GHRH(1-29) backbone, one bolt-on linker, ~1,000x PK difference.
TB-500 is a 7-aa fragment of thymosin beta-4 (43 aa, ~4,963 Da), not the full protein. Cross-COA review: ~67% of "TB-500" vials are actually full Tβ4.