TB-500 Peptide: What It Is, What the Research Shows, and Where to Buy It (2026)

What the research literature covers

The larger literature belongs mainly to full-length thymosin beta-4. In vitro and animal studies examine actin binding, cell migration, cytoskeletal organization, dermal and corneal models, cardiac biology, inflammation, and progenitor-cell activity. These papers establish why the parent protein became a research subject, but their scope remains tied to the molecule, model, and route each team studied.

The strict Ac-LKKTETQ fragment has a much smaller direct record, and one 2024 analytical study is worth knowing in detail. Rahaman and colleagues, writing in the Journal of Chromatography B, developed a method to quantify TB-500 alongside its metabolites and then screened those species for wound-healing activity in vitro. Ac-LKKTETQ itself did not enhance wound healing in that assay. A shorter metabolite, Ac-LKKTE, did. The finding matters because it measures the fragment as its own analyte, and because it raises the possibility that a breakdown product, rather than the intact heptapeptide, carries the activity researchers have been attributing to it.

Community discussion also frequently pairs the name TB-500 with BPC-157 under the "Wolverine" label. That convention describes how the compounds are discussed, not a shared evidence base. Curo's BPC-157 and TB-500 research pairing groups the materials commercially, while the sibling profile on BPC-157's research and trial record covers that compound separately.

TB-500 vs BPC-157: what actually differs

TB-500 and BPC-157 are separate molecules with separate evidence bases that are commonly sold and discussed together. TB-500 is a seven-residue fragment of a human actin-binding protein, and its literature runs through actin sequestration, cell migration, and cytoskeletal work, mostly on the full-length parent. BPC-157 is a 15-residue gastric peptide, sequence GEPPPGKPADDAGLV, with three decades of rodent data and two registered Phase 1 studies.

Two practical differences follow from that. First, BPC-157 has a direct human trial now underway; TB-500's registry entries belong to the parent protein rather than the fragment. Second, the certificate check differs: a BPC-157 COA answers a purity question, while a TB-500 COA has to answer an identity question first, because the fragment and the parent are both sold under one name. Both compounds are prohibited in sport, and both received the same 8 to 6 advisory committee vote in July 2026.

Where the trial record stands

Clinical trial registries make the identity split especially visible. The registered entries are filed under "Thymosin Beta 4," not "TB-500," and the active substance descriptions refer to full-length or recombinant material.

RegeneRx registered RGN-352 as injectable thymosin beta-4 for acute myocardial infarction. ClinicalTrials.gov lists NCT01311518 as withdrawn and states that the study was never initiated. It produced no participant dataset.

Beijing Northland Biotech later sponsored a Phase IIa study of recombinant human thymosin beta-4. NCT05485818 is listed as completed on November 18, 2021. The same sponsor's Phase IIc study of recombinant human thymosin beta-4 injection, NL005, is another parent-protein program. NCT07586865 lists a May 18, 2026 start date and remains not yet recruiting.

Taken together, these records describe a clinical development program for thymosin beta-4. The seven-residue fragment has its own, much shorter registry footprint, which is worth holding separately when reading either one.

Regulatory status in 2026

FDA's 2026 compounding review names the fragment directly. An April 16, 2026 Federal Register notice scheduled a Pharmacy Compounding Advisory Committee meeting for July 23 and 24 and listed "TB-500 (free base)/TB-500 acetate" among nominated bulk drug substances, with wound healing as the indication considered. The committee recommended it. Voting separately on the free base and the acetate, it backed each by 8 in favor to 6 against with one abstention, the same split it gave BPC-157 and KPV that day. Hyman, Phelps & McNamara reported the result, and Pharmaceutical Executive and McDermott Will & Schulte published the same figures. FDA's own staff had recommended against listing, its briefing document for TB-500 citing no human exposure data and potential immunogenicity, aggregation and impurity concerns for injectable use.

A committee recommendation is advisory. Adding a substance to the section 503A list requires formal FDA rulemaking, so TB-500 is not on that list today.

Thymosin beta-4 also has a separate historical designation. FDA granted orphan drug designation to "Thymosin beta 4" on May 28, 2004 for epidermolysis bullosa. Its status is "Designated," which is not an approval, and the record names the parent protein rather than TB-500 fragment material.

For sport, WADA's 2026 Prohibited List took effect January 1, 2026 and places thymosin-beta-4 and its derivatives in section S2.3, Growth Factors and Growth Factor Modulators. They are prohibited at all times, in and out of competition, as non-Specified Substances. WADA published its 2027 Prohibited List on September 21, 2026, and it takes effect January 1, 2027. Enforcement is not hypothetical: USADA announced a four-year period of ineligibility for triathlete Anthony McCauley on September 17, 2025 involving TB-500 and BPC-157.

Is TB-500 legal to buy?

In the United States, TB-500 is legal to purchase as a research chemical for laboratory use. It is not a controlled substance and does not appear on any DEA schedule as of August 2026. What it also is not: an approved drug, a dietary supplement ingredient, or a compound cleared for human or veterinary use in any form.

Three boundaries define the current legal picture:

1. Research sale is lawful; human-use marketing is not. The FDA has repeatedly cited peptide sellers whose sites promote human use, and courts have treated that line seriously. The owner of one vendor, Paradigm Peptides, was sentenced to 70 months in federal prison in July 2026 for selling unapproved and adulterated drugs. The offense was not stocking peptides. It was selling them for human consumption while faking the paperwork.
2. Sport is stricter than law. WADA prohibits thymosin beta-4 and its derivatives, including TB-500, at all times for tested athletes under section S2.3, regardless of the compound's legal status as a research chemical.
3. The compounding question is open, not settled. The July 2026 advisory vote points toward possible pharmacy compounding for wound healing in the future. Until FDA completes rulemaking, no compounded or prescription form exists lawfully in the US.

Curo supplies the material for laboratory work under its research use only policy. That commercial category is separate from the FDA substance identity, compounding review, orphan designation, and sport rules above.

Where to buy TB-500 for laboratory research

Researchers looking for where to buy TB-500 face a supplier market that changed sharply in 2025 and 2026. Peptide Sciences closed in March 2026, Amino Asylum went offline after a reported federal raid in June 2025, and Paradigm Peptides ended in a criminal sentencing. Several sites now trade on those dead brand names, so the first check is not price. It is whether the company behind the storefront actually exists. Our guide to the best peptide companies in 2026 covers the current field vendor by vendor.

TB-500 adds a check the other compounds do not need. Because the fragment and the full-length parent are both sold under the same name, the listing and the certificate should agree on which molecule is in the vial. A page that quotes a 43-residue sequence and a mass near 4,963 g/mol is describing thymosin beta-4, not the 889 g/mol heptapeptide.

Five checks separate a documented TB-500 source from an anonymous one:

1. A lot-specific COA, published before purchase. The certificate should match the exact lot on the vial, not a generic product-page badge. The help center shows how to verify a certificate against your lot.
2. A named, independent laboratory. A COA is only as good as the lab that issued it. Court records in the Paradigm case showed the defendants admitted faking certificates outright, which is the failure mode this check exists to catch.
3. Identity and purity by more than one method. HPLC purity alone leaves the fragment-versus-parent gap wide open. Look for LC-MS identity confirmation and endotoxin results alongside it.
4. An identifiable company. A legal entity, a real contact route, and consistent policies. A brand name alone is not an identity, and the clone sites trading on dead vendors prove it.
5. Payment with recourse. Card payment carries buyer protection. Venmo, Zelle, and crypto-only checkouts remove it.

Curo stocks TB-500 5mg and the BPC-157 + TB-500 pairing in the research catalog. Every lot is tested by an independent laboratory for identity (LC-MS), purity (HPLC), and endotoxin, the full testing standard is documented, and every certificate is publicly readable without an account. Orders are fulfilled from the United States, and payment options include card, crypto, Zelle, and Cash App.

How much does TB-500 cost?

As of August 2026, research-grade TB-500 in the 5mg vial size typically runs $50 to $85 from US suppliers that publish lot-matched, independently issued COAs. Cheaper vials exist, some near $30, but they cluster among suppliers that offer certificates only on request or publish no lot record at all, and an unverified lot is unusable as research material at any price. Curo's TB-500 5mg is $54, at the lower end of the documented tier, and the BPC-157 + TB-500 set (5mg + 5mg) is $108. Compare the documentation attached to the current batch first, then the price. The pre-purchase checklist walks the full sequence.

Reading a TB-500 certificate of analysis

For TB-500, a COA should answer the identity question before it answers broader quality questions. The analyte name should correspond to the vial, and the record should make clear whether the tested material is Ac-LKKTETQ, the thymosin beta-4 17-23 fragment, rather than full-length thymosin beta-4.

A certificate worth relying on shows:

• The exact lot number that appears on the vial, matching the identifier on the published report. The guide to verifying a certificate against a specific lot walks through that check.
• The issuing laboratory's name and report identifier.
• HPLC purity with the chromatogram, not a bare percentage.
• Mass-spectrometry identity confirmation that agrees with the declared fragment rather than the parent protein.
• An endotoxin result, since a pure peptide can still carry bacterial contamination from synthesis.
• A way to verify the document independently, through a public lookup or the lab itself. Curo's COA database is open for exactly this reason.

The order matters here more than it does for most peptides. A high HPLC purity figure says a sample is clean; it does not say whether the clean thing in the vial is the seven-residue fragment or the 43-residue parent. Only the identity label and the LC-MS result together answer that. Once the paperwork lines up, the research-peptide storage guidance covers handling from receipt onward.

For a broader framework on separating documentation from marketing when comparing suppliers, see how to evaluate research peptide companies and the companion piece on purity claims and COA batch documentation.

Further reading

Identity confusion is a wider problem than TB-500. GHK-Cu raises its own version of it, because the copper complex and the free peptide carry separate registry entries and a purity figure alone will not tell them apart. That case is worked through in GHK-Cu across its cosmetic and research contexts.

CJC-1295 presents the same problem in another form, where one market name covers both a short-lived peptide and a long-acting albumin-binding conjugate. That case is set out in CJC-1295 with and without DAC.

Semax was reviewed at that same July 2026 meeting, and it reaches the agenda from an entirely different direction: decades of Russian clinical literature paired with an empty US trial registry. That case is covered in Semax and the 2026 review list.

Two other fragment-versus-parent cases are worth reading alongside this one. AOD-9604 is the 176 to 191 fragment of growth hormone, and its story is covered in the AOD-9604 profile. Thymosin alpha-1 is routinely confused with thymosin beta-4 despite being a different peptide with a different anti-doping status, which is addressed in the thymosin alpha-1 record.

The same fragment-versus-parent question arrives again inside a blend. TB-500 is one of four named peptides in KLOW, each with its own identity record on one document, as set out in One vial, four analytes: reading a KLOW certificate.

Frequently asked questions

What is TB-500?

TB-500 is a synthetic seven-amino-acid peptide, Ac-LKKTETQ, corresponding to residues 17-23 of thymosin beta-4. FDA catalogs it under its own UNII, separate from the 43-residue parent protein. It is not approved for any use and is sold in the United States as a research chemical.

Is TB-500 the same molecule as thymosin beta-4?

No. FDA catalogs them separately. TB-500 is the acetylated seven-amino-acid 17-23 fragment, while thymosin beta-4 is the 43-residue parent protein.

Is TB-500 legal to buy in the US?

Yes, as a research chemical for laboratory use. It is not a controlled substance as of September 2026. It is not approved for human use, no lawful compounded form exists yet, and WADA prohibits thymosin beta-4 and its derivatives for tested athletes at all times.

Where can a researcher buy TB-500?

From suppliers that publish lot-specific, independently issued COAs and operate as identifiable companies. Several well-known vendors closed or faced federal action in 2025 and 2026, and clone sites now trade on their names, so verify the company before the price. Curo lists TB-500 for laboratory research with every lot's certificate published openly.

How much does TB-500 cost?

Suppliers that publish lot-matched third-party COAs typically charge $50 to $85 for a 5mg research vial as of August 2026. Curo's 5mg vial is $54 with the lot's certificate published before purchase. Vials well under that range usually come without verifiable lot documentation.

What is the difference between TB-500 and BPC-157?

They are different molecules with separate research records that are commonly sold together. TB-500 is a seven-residue thymosin beta-4 fragment; BPC-157 is a 15-residue gastric peptide with a much larger rodent literature and a Phase 2 trial recruiting since 2026. The pairing is a naming convention, not shared evidence.

Have registered clinical trials studied the TB-500 fragment?

The registered trials described here are filed under thymosin beta-4, and their substance descriptions identify full-length or recombinant material. Direct registry entries for the Ac-LKKTETQ fragment are a separate and much smaller set.

Is TB-500 banned in sport?

Yes. WADA places thymosin-beta-4 and its derivatives in section S2.3 of the 2026 Prohibited List, prohibited at all times, and USADA sanctioned an athlete over TB-500 in 2025.

What is the first identity check on a TB-500 COA?

Confirm that the lot-specific report names the TB-500 fragment, Ac-LKKTETQ or thymosin beta-4 residues 17-23, and that its LC-MS identity result aligns with that declaration.